Covered Loans - Schedule of Acquired Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Impaired Loans By Type [Line Items]
Beginning balance	$ 131,038	$ 247,752
Principal reductions and interest payments	(58,243)	(78,174)
Accretion of loan discount	24,950	19,174
Changes in contractual and expected cash flows due to remeasurement	2,353	134
Removals due to foreclosure or sale	(5,433)	(8,479)
Ending balance	94,665	180,407
Contractual Cash Flows [Member]
Impaired Loans By Type [Line Items]
Beginning balance	251,042	424,527
Principal reductions and interest payments	(56,475)	(78,174)
Changes in contractual and expected cash flows due to remeasurement	(6,170)	(14,514)
Removals due to foreclosure or sale	(6,138)	(7,764)
Ending balance	182,259	324,075
Non Accretable Difference [Member]
Impaired Loans By Type [Line Items]
Beginning balance	(46,793)	(90,996)
Principal reductions and interest payments	(828)
Changes in contractual and expected cash flows due to remeasurement	23,017	23,521
Removals due to foreclosure or sale	1,670	948
Ending balance	(22,934)	(66,527)
Accretable Yield [Member]
Impaired Loans By Type [Line Items]
Beginning balance	(73,211)	(85,779)
Principal reductions and interest payments	(940)
Accretion of loan discount	24,950	19,174
Changes in contractual and expected cash flows due to remeasurement	(14,494)	(8,873)
Removals due to foreclosure or sale	(965)	(1,663)
Ending balance	$ (64,660)	$ (77,141)