Derivatives and Hedging Activities - Summary of Cash Flow Hedges (Detail) - Cash flow hedges [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Notional Amount, Derivative assets	$ 136,820	$ 72,262
Notional Amount, Derivative liabilities	457,124	440,637
Notional Amount, Total	593,944	512,899
Fair Value, Derivative assets	1,207	2,379
Fair Value, Derivative liabilities	(34,097)	(29,777)
Fair Value, Total	(32,890)	(27,398)
Accumulated Other Comprehensive Income (Loss) [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Derivative assets	815	2,055
Fair Value, Derivative liabilities	(38,512)	(34,311)
Fair Value, Total	(37,697)	(32,256)
Net gain (loss) to be reclassified within 12 months	$ 34,000	$ 26,700