Derivative Instruments - Reconciles Net Amounts Derivative Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative assets	$ 7,524	$ 4,061
Noncurrent derivative assets	0	0
Net amounts of assets on balance sheet	7,524	4,061
Derivative liabilities	(17,797)	(59,489)
Noncurrent derivative liabilities	0	0
Net amounts of liabilities on balance sheet	(17,797)	(59,489)
Total derivative assets, net	$ (10,273)	$ (55,428)