Derivative Instruments - Schedule of Derivative Instruments Classified as Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Fair Market Value, Assets Current Portion	$ 16,148	$ 19,445
Fair Market Value, Assets Long-Term Portion	17,341	9,628
Fair Market Value, Liabilities Current Portion	3,188	8,409
Fair Market Value, Liabilities Long-Term Portion	24,464	20,972
Designated Derivative Instruments [Member] \| Interest rate swaps [Member]
Derivative [Line Items]
Fair Market Value, Assets Current Portion	195	0
Fair Market Value, Assets Long-Term Portion	11,280	1,968
Fair Market Value, Liabilities Current Portion	2,756	4,397
Fair Market Value, Liabilities Long-Term Portion	21,279	17,961
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	0	228
Fair Market Value, Liabilities Current Portion	347	858
Fair Market Value, Liabilities Long-Term Portion	656	2,542
Undesignated Derivative Instruments [Member] \| Energy derivative [Member]
Derivative [Line Items]
Fair Market Value, Assets Current Portion	12,198	19,440
Fair Market Value, Assets Long-Term Portion	0	7,432
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	3,755	5
Fair Market Value, Assets Long-Term Portion	6,061	0
Fair Market Value, Liabilities Current Portion	85	3,154
Fair Market Value, Liabilities Long-Term Portion	$ 2,529	$ 469

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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