Covered Loans - Schedule of Acquired Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Impaired Loans By Type [Line Items]
Beginning balance	$ 247,752	$ 456,788
Principal reductions and interest payments	(119,564)	(153,170)
Accretion of loan discount	28,103	37,919
Changes in contractual and expected cash flows due to remeasurement	560	(5,317)
Removals due to foreclosure or sale	(9,033)	(16,647)
Ending balance	147,818	319,573
Contractual [Member]
Impaired Loans By Type [Line Items]
Beginning balance	424,527	729,496
Principal reductions and interest payments	(119,564)	(153,170)
Changes in contractual and expected cash flows due to remeasurement	(20,348)	13,829
Removals due to foreclosure or sale	(8,586)	(27,373)
Ending balance	276,029	562,782
Non Accretable Difference [Member]
Impaired Loans By Type [Line Items]
Beginning balance	(90,996)	(180,655)
Changes in contractual and expected cash flows due to remeasurement	37,597	16,532
Removals due to foreclosure or sale	746	11,137
Ending balance	(52,653)	(152,986)
Accretable Yield [Member]
Impaired Loans By Type [Line Items]
Beginning balance	(85,779)	(92,053)
Accretion of loan discount	28,103	37,919
Changes in contractual and expected cash flows due to remeasurement	(16,689)	(35,678)
Removals due to foreclosure or sale	(1,193)	(411)
Ending balance	$ (75,558)	$ (90,223)