Loans And Allowance For Credit Losses (Summary Of Changes In The Allowance For Credit Losses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	$ (42,145)	$ 1,494
Change In Allowance Covered By F D I C Indemnification	0	(38)
Allowance for Loan and Lease Losses, Write-offs	(48,110)	(20,188)
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	606,048	604,663
Net loan and lease charge-offs	(36,299)	16,882
Balance at end of period	69,026	82,287
Allowance for loan losses	606,048	604,663	$ 611,894	$ 606,048	$ 620,013	$ 604,663
Reserve for unfunded lending commitments	69,026	82,287	69,026	74,838	82,287	81,076
Total allowance for credit losses			680,920		702,300
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	11,811	37,070
Provision for Unfunded Lending Commitments	(5,812)	1,211
Balance at end of period	611,894	620,013
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	(45,875)	(24,934)
Change In Allowance Covered By F D I C Indemnification	0	(38)
Allowance for Loan and Lease Losses, Write-offs	(43,230)	(15,951)
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	454,277	412,514
Net loan and lease charge-offs	(36,165)	4,662
Balance at end of period	56,267	62,775
Allowance for loan losses	454,277	412,514	463,987	454,277	442,072	412,514
Reserve for unfunded lending commitments	56,267	62,775	56,267	57,696	62,775	58,931
Total allowance for credit losses			520,254		504,847
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	7,065	20,613
Provision for Unfunded Lending Commitments	(1,429)	3,844
Balance at end of period	463,987	442,072
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	(1,701)	$ 26,887
Change In Allowance Covered By F D I C Indemnification	0
Allowance for Loan and Lease Losses, Write-offs	(975)	$ (626)
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	113,992	145,009
Net loan and lease charge-offs	2,019	13,493
Balance at end of period	12,759	18,937
Allowance for loan losses	113,992	145,009	117,712	113,992	131,615	145,009
Reserve for unfunded lending commitments	12,759	18,937	12,759	16,526	18,937	21,517
Total allowance for credit losses			130,471		150,552
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	2,994	14,119
Provision for Unfunded Lending Commitments	(3,767)	(2,580)
Balance at end of period	117,712	131,615
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	5,431	$ (459)
Change In Allowance Covered By F D I C Indemnification	0
Allowance for Loan and Lease Losses, Write-offs	(3,905)	$ (3,611)
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	37,779	47,140
Net loan and lease charge-offs	(2,153)	(1,273)
Balance at end of period	0	575
Allowance for loan losses	37,779	47,140	30,195	37,779	46,326	47,140
Reserve for unfunded lending commitments	0	575	0	$ 616	575	$ 628
Total allowance for credit losses			$ 30,195		$ 46,901
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	1,752	2,338
Provision for Unfunded Lending Commitments	(616)	(53)
Balance at end of period	$ 30,195	$ 46,326