Fair Value of Financial Instruments - Schedule of Company's Reconciliation of Level 3 assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Investment Securities Available for Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		$ 4,745
Transfers in or out of Level 3		(2,745)
Ending balance	2,000	2,000
Impaired Loans Carried at Fair Value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	70,296	84,573
Transfers in or out of Level 3	(17,782)	(14,277)
Ending balance	52,514	70,296
Other Real Estate Owned [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	50,301	57,915
Total gains (losses) included in operations	(11,843)	(14,570)
Purchases, sales, issuances, and settlements, net	(20,428)	(26,323)
Transfers in or out of Level 3	21,820	33,279
Ending balance	39,850	50,301
Covered Loan [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	571,489	554,991
Purchases, sales, issuances, and settlements, net	(20,479)	48,734
Transfers in or out of Level 3	(43,298)	(32,236)
Ending balance	507,712	571,489
Covered Other Real Estate Owned [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	78,617	54,931
Total gains (losses) included in operations	2,892	(28)
Purchases, sales, issuances, and settlements, net	(36,534)	(8,522)
Transfers in or out of Level 3	43,298	32,236
Ending balance	$ 88,273	$ 78,617