Summary of Provision for Credit Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Provision for non-covered loans	$ 7,429	$ 6,422	$ 12,803	$ 11,627
Provision for covered loans		(788)		18,094
Total provision for loan losses	7,429	5,634	12,803	29,721
Provision for unfunded letters of credit	(24)	392	299	467
Total provision for credit losses	$ 7,405	$ 6,026	$ 13,102	$ 30,188