Allowance For Loan Losses, Allowance For Losses On Lending-Related Commitments And Impaired Loans (Summary Of Activity In The Allowance For Covered Loan Losses) (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
Allowance for Covered Loan Losses [Roll Forward]
Balance at beginning of period	$ 20,560	$ 7,443	$ 12,977	$ 0
Provision for covered loan losses before benefit attributable to FDIC loss share agreements	3,096	5,139	25,916	12,582
Benefit attributable to FDIC loss share agreements	(2,489)	(4,112)	(20,766)	(10,066)
Net provision for covered loan losses	607	1,027	5,150	2,516
Increase in FDIC indemnification asset	2,489	4,112	20,766	10,064
Loans charged-off	(1,736)	(86)	(17,052)	(86)
Recoveries of loans charged-off	6	0	85	2
Net charge-offs	(1,730)	(86)	(16,967)	(84)
Balance at end of period	$ 21,926	$ 12,496	$ 21,926	$ 12,496