Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investment securities available-for-sale: Before-Tax
Net change in fair value recorded in accumulated OCI, Before-Tax	$ (88,562)	$ 3,074	$ 61,490
Net realized gains reclassified into earnings, Before-Tax	(2,094)		(656)
Other comprehensive (loss) income, before tax	(90,656)	3,074	60,834
Net change in fair value recorded in accumulated OCI, Before-Tax	(88,562)	3,074	61,490
Investment securities available-for-sale: Tax Effect
Net change in fair value recorded in accumulated OCI, Tax Effect	(37,196)	1,292	25,826
Net realized gains reclassified into earnings, Tax Effect	(879)
Net change, Tax Effect	(38,075)	1,292	25,550
Investment securities held-to-maturity: Before-Tax
Reclassification of credit-related OTTI from accumulated OCI, Before-Tax			(656)
Investment securities available-for-sale: After-Tax
Net change in fair value recorded in accumulated OCI, After-Tax	(51,366)	1,782	35,664
Net realized gains reclassified into earnings, After-Tax	(1,215)
Other comprehensive (loss) income, net of tax	(52,581)	1,782	35,284
Other comprehensive (loss) income, before tax	(90,656)	3,074	60,834
Net change in fair value recorded in accumulated OCI, Tax Effect	(37,196)	1,292	25,826
Investment securities held-to-maturity: Tax Effect
Reclassification of credit-related OTTI from accumulated OCI, Tax Effect			(276)
Net change, Tax Effect	(38,075)	1,292	25,550
Net change in fair value recorded in accumulated OCI, After-Tax	(51,366)	1,782	35,664
Investment securities held-to-maturity: After-Tax
Reclassification of credit-related OTTI from accumulated OCI, After-Tax			(380)
Other comprehensive (loss) income, net of tax	$ (52,581)	$ 1,782	$ 35,284

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