Business Combinations (Summary Of FDIC Indemnification Asset) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
FDIC Indemnification Asset [Roll Forward]
Balance at beginning of period	$ 208,160	$ 344,251
Additions from acquisitions	0	13,164
Additions from reimbursable expenses	5,033	6,864
Accretion	(2,468)	(1,576)
Changes in expected reimbursements from the FDIC for changes in expected credit losses	(26,097)	(17,213)
Payments received from the FDIC	(13,932)	(82,278)
Balance at end of period	$ 170,696	$ 263,212