Basis of Presentation and Accounting Policies - Schedule of Company's Reconciliation of Level 3 Assets (Detail) (USD $) In Thousands, unless otherwise specified					9 Months Ended
	Sep. 30, 2013 Investment Securities Available for Sale [Member]	Dec. 31, 2012 Investment Securities Available for Sale [Member]	Sep. 30, 2012 Investment Securities Available for Sale [Member]	Dec. 31, 2011 Investment Securities Available for Sale [Member]	Sep. 30, 2013 Impaired Loans Carried at Fair Value [Member]	Sep. 30, 2012 Impaired Loans Carried at Fair Value [Member]	Sep. 30, 2013 Other Real Estate Owned [Member]	Sep. 30, 2012 Other Real Estate Owned [Member]	Sep. 30, 2013 Covered Loans [Member]	Sep. 30, 2012 Covered Loans [Member]	Sep. 30, 2013 Covered Other Real Estate Owned [Member]	Sep. 30, 2012 Covered Other Real Estate Owned [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 2,000	$ 2,000	$ 2,000	$ 2,000	$ 52,514	$ 70,296	$ 39,850	$ 46,680	$ 507,712	$ 571,489	$ 88,273	$ 78,617
Total gains/(losses) included in net income							(2,214)	(9,048)			(3,432)
Purchases, sales, issuances, and settlements, net					(621)		(7,987)	(21,008)	(61,338)	15,281	(61,014)	(30,258)
Transfers in to Level 3						842
Asset reclassification, within Level 3					(8,329)	(20,701)	8,329	20,701	(28,725)	(40,536)	28,725	40,536
Ending balance	$ 2,000	$ 2,000	$ 2,000	$ 2,000	$ 43,564	$ 50,437	$ 37,978	$ 37,325	$ 417,649	$ 546,234	$ 52,552	$ 88,895