Income Taxes - Schedule of Significant Components of Net Deferred Tax Assets (Liabilities) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred Tax Assets
Allowance for loan losses, net of recapture	$ 16,891	$ 20,861
Benefit plan accruals	15,331	18,389
AMT credit	21,268	23,029
Unrealized losses on benefit plans	4,011	8,347
Net operating loss carryforwards	3,763	5,135
Premises and equipment	24,221	30,790
Federal tax credits	422	0
Other-than-temporary-impairment	4,939	7,546
Loans - ASC 310	51,546	90,516
Other real estate owned		8,715
Lease exit obligation	2,654	1,232
Unrealized losses on available-for-sale investment securities	13,276
Unrealized losses on held-to-maturity investment securities	8,567
Unrealized losses on hedges	116
Other, net	5,406	5,415
Total deferred tax assets	172,411	219,975
Deferred Tax Liabilities
Accretion on investment securities	(438)	(590)
Lease receivable, net	(395)	(3,757)
Other real estate owned	(701)
Purchase accounting	(7,355)	(6,737)
FDIC indemnification asset	(27,938)	(64,152)
Unrealized gains on available-for-sale investment securities		(24,972)
Unrealized gains on held-to-maturity securities		(2,177)
Other, net	(2,028)	(1,274)
Total deferred tax liabilities	(38,855)	(103,659)
Net deferred tax assets	$ 133,556	$ 116,316