Derivative Instruments - Effects of Gains and Losses from Derivative Instruments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives	$ 474	$ 1,084	$ 1,313
Call options
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain on Derivative	209
Revenue | Derivatives not designated as hedging instruments | Forward Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain on Derivative	426	1,423	1,127
Gain (Loss) on derivatives	(126)	57	217
Cost of Sales | Derivatives designated as fair value hedges | Put/Call Option
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	528	235	(28)
Cost of Sales | Derivatives designated as fair value hedges | Call options
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(81)	(17)	0
Cost of Sales | Derivatives designated as fair value hedges | Propane Swap Agreement
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(120)	(341)	0
Cost of Sales | Derivatives not designated as hedging instruments | Call options
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain on Derivative	0	0	97
Cost of Sales | Derivatives not designated as hedging instruments | Propane Swap Agreement
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain on Derivative			0
Derivative, Gain (Loss) on Derivative, Net	18	(735)
Propane Inventory | Derivatives designated as fair value hedges | Put/Call Option
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives	43	517	(100)
Other Comprehensive Income (Loss) [Member] | Derivatives designated as fair value hedges | Call options
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives	0	(55)	0
Other Comprehensive Income (Loss) [Member] | Derivatives designated as fair value hedges | Propane Swap Agreement
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives	(323)	0	0
Other Comprehensive Income (Loss) [Member] | Derivatives designated as fair value hedges | Future [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on derivatives	$ 109	$ 0	$ 0