Business Combinations (Summary Of FDIC Indemnification Asset) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
FDIC Indemnification Asset [Roll Forward]
Balance at beginning of period	$ 222,568	$ 110,049	$ 344,251	$ 118,182
Additions from acquisitions	65,100	273,311	78,264	328,837
Additions from reimbursable expenses	5,669	3,707	18,646	8,778
Accretion	(1,139)	393	(3,919)	1,057
Changes in expected reimbursements from the FDIC for changes in expected credit losses	(16,579)	(344)	(46,343)	(12,510)
Payments received from the FDIC	(37,314)	(7,810)	(152,594)	(65,038)
Balance at end of period	$ 238,305	$ 379,306	$ 238,305	$ 379,306