Assets Acquired in FDIC-Assisted Acquisitions - Rollforward of Acquired Loans Deterioration of Credit Quality (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2012
Covered Loans [Line Items]
Balance, beginning of year	$ 25,493	$ 16,698	$ 16,698	$ 16,091	$ 13,532
Additions due to acquisitions
Balance, end of year	53,181	160,979	65,441			159,724
Loans with Deterioration of Credit Quality [Member]
Covered Loans [Line Items]
Balance, beginning of year	217,047	282,737	282,737
Change in estimate of cash flows, net of charge-offs or recoveries	4,659	(5,391)	35,306
Additions due to acquisitions
Other (loan payments, transfers, etc.)	(16,505)	(22,279)	(100,996)
Balance, end of year	205,201	255,067	217,047
Loans without Deterioration of Credit Quality [Member]
Covered Loans [Line Items]
Balance, beginning of year	173,190	228,602	228,602
Change in estimate of cash flows, net of charge-offs or recoveries	2,571	(2,625)	13,471
Additions due to acquisitions
Other (loan payments, transfers, etc.)	(8,268)	(20,229)	(68,883)
Balance, end of year	$ 167,493	$ 205,748	$ 173,190