Fair Values - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Assets
Derivatives	$ 3,730	$ 1,138
Other assets, at fair value	13,073	49,017
Liabilities
Derivatives	368
Level 2 [Member]
Assets
Derivatives	3,730	1,138
Other assets, at fair value	377	1,510
Liabilities
Derivatives	368
Level 3 [Member]
Assets
Other assets, at fair value	$ 12,696	$ 47,507