Allowance for Loan Losses Details Textual (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Allowance For Loan And Lease Losses [Line Items]
Loan Commitments	$ 5,116,633,000	$ 3,892,865,000	$ 5,116,633,000	$ 3,892,865,000		$ 4,151,541,000
Minimum Non Performing Substandard Loans Outstanding for Allowance for Credit Losses	300,000		300,000
Minimum Non Performing Substandard Doubtful Loans Outstanding for Allowance for Credit Losses	100,000		100,000
Nonaccrual Non-reaffirmed Bankruptcies	9,400,000		9,400,000			7,700,000
Covered Loans [Member]
Allowance For Loan And Lease Losses [Line Items]
Loans and Leases Receivable, Allowance, Covered	49,069,000	42,606,000	49,069,000	42,606,000	47,945,000	43,255,000	41,070,000	36,417,000
Provision for Loan Losses Before Benefit Attributable to FDIC Loss Share Agreements	6,477,000	9,648,000	16,154,000	20,479,000
Benefit Attributable to FDIC Loss Share Agreements	(2,319,000)	(6,218,000)	(7,858,000)	(11,117,000)
Loans with No Related Allowance [Member]
Allowance For Loan And Lease Losses [Line Items]
Loan Commitments	$ 200,000		$ 200,000