Fair Values - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets
Derivatives	$ 4,086	$ 8,657
Liabilities
Derivatives	210	1,448
Recurring [Member]
Assets
Derivatives	4,086	8,657
Other assets		14,220
Liabilities
Derivatives	210	1,448
Level 2 [Member] | Recurring [Member]
Assets
Derivatives	4,086	8,657
Other assets		1,659
Liabilities
Derivatives	$ 210	1,448
Level 3 [Member] | Recurring [Member]
Assets
Other assets		$ 12,561