$ 92,682

$ 100,497

$ 262,763

$ 286,834

92,682

100,497

262,763

286,834

Other income, net of other expenses

13,170

10,457

50,678

42,079

(171)

405

(38)

413

Interest

2,485

2,303

4,933

4,459

Income Before Income Taxes

10,514

8,559

45,707

38,033

Income taxes

4,220

3,425

18,304

15,218

Net Income

6,294

5,134

27,403

22,815

36,092

970,636

904,469

Regulated Energy [Member]

13,605

10,711

35,788

31,802

800,719

796,021

Unregulated Energy [Member]

(540)

(43)

14,689

10,815

147,102

84,732

Other [Member]

22,815

23,716

Other and eliminations [Member]

105

(211)

201

(538)

Operating Revenues, Unaffiliated Customers [Member]

92,682

100,497

262,763

286,834

92,682

100,497

262,763

286,834

Operating Revenues, Unaffiliated Customers [Member] | Regulated Energy [Member]

61,790

61,348

171,082

163,222

61,790

61,348

171,082

163,222

Operating Revenues, Unaffiliated Customers [Member] | Unregulated Energy [Member]

30,892

34,299

91,681

114,173

30,892

34,299

91,681

114,173

Operating Revenues, Unaffiliated Customers [Member] | Other [Member]

4,850

9,439

4,850

9,439

Intersegment Revenues [Member]

2,156

^[1]

568

^[1]

2,873

1,213

2,156

^[1]

568

^[1]

2,873

1,213

Intersegment Revenues [Member] | Regulated Energy [Member]

270

^[1]

298

^[1]

560

^[1]

590

^[1]

270

^[1]

298

^[1]

560

^[1]

590

^[1]

Intersegment Revenues [Member] | Unregulated Energy [Member]

1,666

^[1]

1,873

^[1]

121

^[1]

1,666

^[1]

1,873

^[1]

121

^[1]

Intersegment Revenues [Member] | Other [Member]

220

^[1]

248

^[1]

440

^[1]

502

^[1]

Amortization of pension and postretirement items:

$ 220

^[1]

$ 248

^[1]

$ 440

^[1]

$ 502

^[1]

[1]	(1) All significant intersegment revenues are billed at market rates and have been eliminated from consolidated operating revenues.

Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Beginning balance	$ (5,676)	$ (2,533)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1)	(1)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	198	61
Net current-period other comprehensive income (loss)	197	60
Ending balance	(5,479)	(2,473)
UnrealizedGainsLossesFromDefinedBenefitPensionAndPostretirementPlanItems [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Beginning balance	(5,643)	(2,533)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	165	61
Net current-period other comprehensive income (loss)	165	61
Ending balance	(5,478)	(2,472)
Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Beginning balance	(33)	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1)	(1)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	33	0
Net current-period other comprehensive income (loss)	32	(1)
Ending balance	$ (1)	$ (1)

Accumulated Other Comprehensive Income (Loss) - Reclassifications of Accumulated Other Comprehensive Loss (Detail) (USD $)

3 Months Ended

6 Months Ended

Jun. 30, 2015

Jun. 30, 2014

Jun. 30, 2015

Jun. 30, 2014

Tax benefit

$ (4,220,000)

$ (3,425,000)

$ (18,304,000)

$ (15,218,000)

Reclassification out of Accumulated Other Comprehensive Income [Member]

Amortization of pension and postretirement items:

Net of tax

(89,000)

(30,000)

(197,000)

(60,000)

Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]

Amortization of pension and postretirement items:

Prior service cost

17,000

^[1]

15,000

^[1]

34,000

^[1]

30,000

^[1]

Net loss

155,000

^[1]

67,000

^[1]

310,000

^[1]

132,000

^[1]

Total before tax

(138,000)

(52,000)

(276,000)

(102,000)

Tax benefit

55,000

21,000

111,000

41,000

Net of tax

(83,000)

(31,000)

(165,000)

(61,000)

Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]

Amortization of pension and postretirement items:

Total before tax

(10,000)

2,000

(53,000)

2,000

Tax benefit

4,000

(1,000)

21,000

(1,000)

Net of tax

(6,000)

1,000

(32,000)

1,000

Other Comprehensive Income Loss Adjustments AOCI Swap Agreements

(10,000)

2,000

Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax

$ 0

$ (55,000)

$ 0

[1]	These amounts are included in the computation of net periodic costs (benefits). See Note 9, Employee Benefit Plans, for additional details.

Employee Benefit Plans - Employee Benefit Plans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Document Period End Date			Jun. 30, 2015
Amortization of prior service cost	$ (17)	$ (15)	$ (34)	$ (30)
Amortization of net loss	249	67	496	132
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	15	16	30	33
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Amortization of net loss	2	0	3	0
Net periodic cost (benefit)	17	16	33	33
Amortization of pre-merger regulatory asset	2	2	4	4
Total periodic cost	19	18	37	37
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	11	13	22	26
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(19)	(20)	(39)	(39)
Amortization of net loss	17	17	35	33
Net periodic cost (benefit)	9	10	18	20
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	9	10	18	20
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	23	23	46	46
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	2	5	5	9
Amortization of net loss	25	12	50	24
Net periodic cost (benefit)	50	40	101	79
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	50	40	101	79
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	626	647	1,251	1,294
Expected return on plan assets	(777)	(772)	(1,554)	(1,545)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	114	0	227	0
Net periodic cost (benefit)	(37)	(125)	(76)	(251)
Amortization of pre-merger regulatory asset	191	191	381	381
Total periodic cost	154	66	305	130
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	102	106	204	213
Expected return on plan assets	(135)	(132)	(270)	(265)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	91	38	181	75
Net periodic cost (benefit)	58	12	115	23
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	$ 58	$ 12	$ 115	$ 23

Employee Benefit Plans - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Document Period End Date			Jun. 30, 2015
Expected pension and postretirement benefit costs			$ 1,200,000
Expected amortization of pre merger regulatory asset			769,000
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	17,000	16,000	33,000	33,000
Contribution to pension plan	24,000		116,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			207,000
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	9,000	10,000	18,000	20,000
Contribution to pension plan	13,000		28,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			79,000
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	50,000	40,000	101,000	79,000
Contribution to pension plan	38,000		71,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			151,000
Consolidated [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost			(381,000)
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	58,000	12,000	115,000	23,000
Contribution to pension plan	115,000		219,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			475,000
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Unamortized balance of regulatory asset	3,200,000		3,200,000		3,600,000
Defined Benefit Plan, Net Periodic Benefit Cost	(37,000)	(125,000)	(76,000)	(251,000)
Contribution to pension plan	381,000		723,000
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			$ 1,600,000

Employee Benefit Plans - Amounts Included in Regulatory Asset and Accumulated Other Comprehensive Income/Loss Recognized as Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	$ (17)	$ (15)	$ (34)	$ (30)
Net loss	249	67	496	132
Recognized from accumulated other comprehensive loss	138	52	276	102
Recognized from regulatory asset	94	0	186	0
Total recognized in net periodic benefit cost	232	52	462	102
Chesapeake Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	0	0	0	0
Net loss	91	38	181	75
Recognized from accumulated other comprehensive loss	91	38	181	75
Recognized from regulatory asset	0	0	0	0
Total recognized in net periodic benefit cost	91	38	181	75
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	0	0	0	0
Net loss	114	0	227	0
Recognized from accumulated other comprehensive loss	22	0	43	0
Recognized from regulatory asset	92	0	184	0
Total recognized in net periodic benefit cost	114	0	227	0
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	2	5	5	9
Net loss	25	12	50	24
Recognized from accumulated other comprehensive loss	27	17	55	33
Recognized from regulatory asset	0	0	0	0
Total recognized in net periodic benefit cost	27	17	55	33
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	(19)	(20)	(39)	(39)
Net loss	17	17	35	33
Recognized from accumulated other comprehensive loss	(2)	(3)	(4)	(6)
Recognized from regulatory asset	0	0	0	0
Total recognized in net periodic benefit cost	(2)	(3)	(4)	(6)
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	0	0	0	0
Net loss	2	0	3	0
Recognized from accumulated other comprehensive loss	0	0	1	0
Recognized from regulatory asset	2	0	2	0
Total recognized in net periodic benefit cost	$ 2	$ 0	$ 3	$ 0

Share-Based Compensation - Share-Based Compensation Amounts Included in Net Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	$ 410	$ 427	$ 947	$ 1,065
Less: tax benefit	(165)	(172)	(381)	(429)
Share-Based Compensation amounts included in net income	245	255	566	636
Awards to non-employee directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	160	132	311	256
Award to key employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	$ 250	$ 295	$ 636	$ 809

Share-Based Compensation - Summary of Stock Activity under the SICP (Detail) (USD $)	6 Months Ended
	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of Shares, Granted	1,207
Award to key employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of Shares, Outstanding - December 31, 2014	123,038
Number of Shares, Granted	29,763
Number of Shares, Vested	(43,839)
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expired In Period	(2,520)
Number of Shares, Outstanding - June 30, 2015	106,442.000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted Average Fair Value, Outstanding - December 31, 2014	$ 32.60
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 48.21
Weighted Average Fair Value, Vested	$ 28.01
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expirations Weighted Average Grant Date Fair Value	$ 28.83
Weighted Average Fair Value, Outstanding - June 30, 2015	$ 37.97
Awards to non-employee directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of Shares, Outstanding - December 31, 2014	0
Number of Shares, Granted	14,484
Number of Shares, Vested	(14,484)
Number of Shares, Outstanding - June 30, 2015	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted Average Fair Value, Outstanding - December 31, 2014	$ 0.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 45.54
Weighted Average Fair Value, Vested	$ 45.54
Weighted Average Fair Value, Outstanding - June 30, 2015	$ 0.00

Share-Based Compensation - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted awards, shares	1,207
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 1,900,000
Awards to non-employee directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amortization of expense equally over a service period	1 year
Unrecognized compensation expense related to the awards to non-employee directors	550,000
Granted awards, shares	14,484
Award to key employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted awards, shares	29,763
Vesting period	3 years
Intrinsic value of the SICP awards	$ 5,700,000

Derivative Instruments Outstanding Trading Contracts (Details) (Forward Contracts [Member])	Jun. 30, 2015 gal
Sales [Member]
Derivative [Line Items]
Quantity In Gallons	4,620,000
Weighted Average Contract Prices	0.4760
Sales [Member] \| Minimum [Member]
Derivative [Line Items]
Estimated Market Prices	0.3475
Sales [Member] \| Maximum [Member]
Derivative [Line Items]
Estimated Market Prices	0.5288
Purchase [Member]
Derivative [Line Items]
Quantity In Gallons	4,620,000
Weighted Average Contract Prices	0.4322
Purchase [Member] \| Minimum [Member]
Derivative [Line Items]
Estimated Market Prices	0.3550
Purchase [Member] \| Maximum [Member]
Derivative [Line Items]
Estimated Market Prices	0.5025

Derivative Instruments - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2015 gal	Dec. 31, 2014 gal
Propane Swap Agreement [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	2,500,000	630,000
Cash Paid On Derivative Settlement	$ 1,100,000
Other Comprehensive Income Loss Adjustments AOCI Swap Agreements		735,000
Call options [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume		1,300,000
Payments for Derivative Instrument, Financing Activities		98,000
Put Option [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	2,500,000	630,000
Payments for Derivative Instrument, Financing Activities	143,000	128,000
Cash Received On Derivative Settlement	868,000
Forward Contracts [Member]
Derivative [Line Items]
Number Of Counterparties With Master Repurchase Agreements	2	2
Accounts Receivable Subject To Master Netting Arrangement	654,000	1,600,000
Accounts Payable Subject To Master Netting Arrangement	222,000	1,200,000
Mark To Market Energy Assets [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Cash Flow Hedge Derivative Instrument Assets at Fair Value	36,000
Mark To Market Energy Liabilities [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value	38,000
Designated as Hedging Instrument [Member] \| Mark To Market Energy Assets [Member] \| Put Option [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 110,000
Strike Price 1 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Strike Price Per Gallon For The Propane Swap Agreements	0.595	1.1350
Strike Price 2 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Strike Price Per Gallon For The Propane Swap Agreements	0.5888	1.0975
Strike Price 3 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Strike Price Per Gallon For The Propane Swap Agreements	0.5500	1.0475
Strike Price 4 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Strike Price Per Gallon For The Propane Swap Agreements	0.5200
Put Option Strike Price 1 [Member] \| Put Option [Member]
Derivative [Line Items]
Derivative, Price Risk Option Strike Price	0.4950	1.0350
Put Option Strike Price 2 [Member] \| Put Option [Member]
Derivative [Line Items]
Derivative, Price Risk Option Strike Price	0.4888	0.9975
Put Option Strike Price 3 [Member] \| Put Option [Member]
Derivative [Line Items]
Derivative, Price Risk Option Strike Price	0.4500	0.9475
Put Option Strike Price 4 [Member] \| Put Option [Member]
Derivative [Line Items]
Derivative, Price Risk Option Strike Price	0.4200
Strike Price 1 [Member] \| Call options [Member]
Derivative [Line Items]
Derivative, Price Risk Option Strike Price	1.0875
Strike Price 2 [Member] \| Call options [Member]
Derivative [Line Items]
Derivative, Price Risk Option Strike Price	1.0650

Derivative Instruments - Fair Values of Derivative Contracts Recorded in Condensed Consolidated Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Energy Marketing Contract Liabilities, Current	$ 47	$ 1,018
Energy Marketing Contracts Assets, Current	358	1,055
Mark To Market Energy Assets [Member] \| Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Energy Marketing Contracts Assets, Current	212	407
Mark To Market Energy Assets [Member] \| Call options [Member]
Derivatives, Fair Value [Line Items]
Energy Marketing Contracts Assets, Current	0	26
Mark To Market Energy Assets [Member] \| Put Option [Member]
Derivatives, Fair Value [Line Items]
Energy Marketing Contracts Assets, Current	110	622
Mark To Market Energy Assets [Member] \| Swap [Member]
Derivatives, Fair Value [Line Items]
Energy Marketing Contracts Assets, Current	36
Mark-to-market energy liabilities [Member] \| Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Energy Marketing Contract Liabilities, Current	9	283
Mark-to-market energy liabilities [Member] \| Propane Swap Agreement [Member]
Derivatives, Fair Value [Line Items]
Energy Marketing Contract Liabilities, Current	$ 38	$ 735

Derivative Instruments - Effects of Gains and Losses from Derivative Instruments on Condensed Consolidated Financial Statements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 112	$ 59	$ 691	$ 1,354
Revenue [Member] \| Derivatives not designated as hedging instruments [Member] \| Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives	203	6	78	(62)
Cost of Sales [Member] \| Derivatives not designated as hedging instruments [Member] \| Call Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	0	137
Cost of Sales [Member] \| Derivatives not designated as hedging instruments [Member] \| Propane Swap Agreement [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	18	0
Cost of Sales [Member] \| Derivatives designated as fair value hedges [Member] \| Call Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(81)	0
Cost of Sales [Member] \| Derivatives designated as fair value hedges [Member] \| Put/Call Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	(29)	506	(49)
Inventories [Member] \| Derivatives designated as fair value hedges [Member] \| Put/Call Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives	(30)	0	(34)	0
Other Comprehensive Income (Loss) [Member] \| Derivatives designated as fair value hedges [Member] \| Propane Swap Agreement [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives	10	(2)	(2)	(2)
Options [Member] \| Revenue [Member] \| Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (71)	$ 84	$ 206	$ 1,330

Fair Value of Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets:
Investments	$ 3,665	$ 3,678
Equity Securities [Member]
Assets:
Investments	16	0
Quoted Prices in Active Markets (Level 1) [Member] \| Mark-to-market energy liabilities [Member]
Liabilities:
Mark-to-market energy liabilities	0	0
Quoted Prices in Active Markets (Level 1) [Member] \| Investments in guaranteed income fund [Member]
Assets:
Investments	0	0
Quoted Prices in Active Markets (Level 1) [Member] \| Equity Securities [Member]
Assets:
Investments	16
Quoted Prices in Active Markets (Level 1) [Member] \| Investments - other [Member]
Assets:
Investments	3,314	3,391
Quoted Prices in Active Markets (Level 1) [Member] \| Mark To Market Energy Assets Including Put Option [Member]
Assets:
Mark-to-market energy assets	0	0
Significant Other Observable Inputs (Level 2) [Member] \| Mark-to-market energy liabilities [Member]
Liabilities:
Mark-to-market energy liabilities	47	1,018
Significant Other Observable Inputs (Level 2) [Member] \| Investments in guaranteed income fund [Member]
Assets:
Investments	0	0
Significant Other Observable Inputs (Level 2) [Member] \| Equity Securities [Member]
Assets:
Investments	0
Significant Other Observable Inputs (Level 2) [Member] \| Investments - other [Member]
Assets:
Investments	0	0
Significant Other Observable Inputs (Level 2) [Member] \| Mark To Market Energy Assets Including Put Option [Member]
Assets:
Mark-to-market energy assets	358	1,055
Significant Unobservable Inputs (Level 3) [Member] \| Mark-to-market energy liabilities [Member]
Assets:
Mark-to-market energy assets	0	0	0
Significant Unobservable Inputs (Level 3) [Member] \| Investments in guaranteed income fund [Member]
Assets:
Investments	335	287
Significant Unobservable Inputs (Level 3) [Member] \| Equity Securities [Member]
Assets:
Investments	0
Significant Unobservable Inputs (Level 3) [Member] \| Investments - other [Member]
Assets:
Investments	0	0
Recurring [Member] \| Mark-to-market energy liabilities [Member]
Liabilities:
Mark-to-market energy liabilities	47	1,018
Recurring [Member] \| Investments in guaranteed income fund [Member]
Assets:
Investments	335	287
Recurring [Member] \| Equity Securities [Member]
Assets:
Investments	16
Recurring [Member] \| Investments - other [Member]
Assets:
Investments	3,314	3,391
Recurring [Member] \| Mark To Market Energy Assets Including Put Option [Member]
Assets:
Mark-to-market energy assets	$ 358	$ 1,055

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Investments (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 287	$ 458
Purchases and adjustments	49	(26)
Transfers	(3)	(25)
Investment Income	2	3
Ending Balance	$ 335	$ 410

Long-Term Debt - Outstanding Long-Term Debt (Detail) (USD $)
In Thousands, unless otherwise specified

Jun. 30, 2015

Dec. 31, 2014

Capital Lease Obligations

$ 159,900

$ 161,500

5,483

6,130

Total Long-term debt

165,374

167,595

Less: current maturities

(9,127)

(9,109)

Total long-term debt, net of current maturities

156,247

158,486

9.08% bond, due June 1, 2022 [Member]

7,971

^[1]

7,969

^[1]

6.64% note, due October 31, 2017 [Member]

8,182

5.50% note, due October 12, 2020 [Member]

12,000

5.93% note, due October 31, 2023 [Member]

25,500

27,000

5.68% note, due June 30, 2026 [Member]

29,000

Uncollateralized Senior Notes Due On May Two Thousand Twenty Eight [Member]

7,000

Uncollateralized Senior Note Two Due on December Two Thousand Twenty Eight [Member]

20,000

Uncollateralized Senior Notes Due On Two Thousand Twenty Nine [Member]

50,000

Promissory note [Member]