Derivative Instruments - Schedule of Derivative Instruments Classified as Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Derivative [Line Items]
Fair Market Value, Assets Current Portion	$ 18,680	$ 17,578
Fair Market Value, Assets Long-Term Portion	16,058	26,712
Fair Market Value, Liabilities Current Portion	11,340	11,918
Fair Market Value, Liabilities Long-Term Portion	24,171	24,521
Designated Derivative Instruments [Member] \| Interest rate swaps [Member]
Derivative [Line Items]
Fair Market Value, Assets Current Portion	0	0
Fair Market Value, Assets Long-Term Portion	0	40
Fair Market Value, Liabilities Current Portion	7,540	8,289
Fair Market Value, Liabilities Long-Term Portion	20,140	21,058
Undesignated Derivative Instruments [Member] \| Interest rate swaps [Member]
Derivative [Line Items]
Fair Market Value, Assets Current Portion	0	0
Fair Market Value, Assets Long-Term Portion	842	1,788
Fair Market Value, Liabilities Current Portion	2,519	3,238
Fair Market Value, Liabilities Long-Term Portion	3,622	3,463
Undesignated Derivative Instruments [Member] \| Energy derivative [Member]
Derivative [Line Items]
Fair Market Value, Assets Current Portion	18,680	16,209
Fair Market Value, Assets Long-Term Portion	15,216	24,707
Fair Market Value, Liabilities Current Portion	0	0
Fair Market Value, Liabilities Long-Term Portion	0	0
Undesignated Derivative Instruments [Member] \| Foreign currency forward contracts [Member]
Derivative [Line Items]
Fair Market Value, Assets Current Portion	0	1,369
Fair Market Value, Assets Long-Term Portion	0	177
Fair Market Value, Liabilities Current Portion	1,281	391
Fair Market Value, Liabilities Long-Term Portion	$ 409	$ 0

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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