Derivative Instruments - Gross Amounts of Recognized Derivative Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amounts of recognized assets	$ 10,060	$ 4,061
Gross amounts offset on balance sheet	(2,536)	0
Net amounts of assets on balance sheet	7,524	4,061
Gross amounts of recognized liabilities	(20,333)	(59,489)
Gross amounts offset on balance sheet	2,536	0
Net amounts of liabilities on balance sheet	$ (17,797)	$ (59,489)