Allowance for Credit Losses (Summary of Activity In Allowance for Loan and Lease Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Forecast period (years)			2 years
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 189,094	$ 222,450	$ 224,314	$ 225,141
Provision (credit)	(1,120)	4,042	(31,697)	52,949
Initial allowance on PCD loans				1,193
Charge-offs	(11,073)	(8,932)	(27,164)	(35,257)
Recoveries	6,293	6,376	17,741	17,834
Ending balance	183,194	223,936	183,194	223,936
Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				(37,924)
Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				187,217
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	76,082	76,177	80,842	142,369
Provision (credit)	975	4,793	332	32,854
Initial allowance on PCD loans				0
Charge-offs	(5,967)	(3,328)	(12,342)	(12,712)
Recoveries	1,594	2,338	3,852	5,023
Ending balance	72,684	79,980	72,684	79,980
Commercial | Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				(87,554)
Commercial | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				54,815
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	94,272	119,345	119,485	75,236
Provision (credit)	(223)	1,874	(23,208)	25,066
Initial allowance on PCD loans				0
Charge-offs	(4,307)	(5,109)	(12,804)	(19,535)
Recoveries	2,330	2,719	8,599	7,433
Ending balance	92,072	118,829	92,072	118,829
Consumer | Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				30,629
Consumer | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				105,865
Unfunded Loan Commitment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,103	13,685	12,814	1,055
Provision (credit)	369	286	(1,342)	4,031
Ending balance	11,472	13,971	11,472	13,971
Unfunded Loan Commitment | Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	0	0	8,885
Unfunded Loan Commitment | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,103	13,685	12,814	9,940
PCD Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	18,740	26,928	23,987	7,536
Provision (credit)	(1,872)	(2,625)	(8,821)	(4,971)
Initial allowance on PCD loans				1,193
Charge-offs	(799)	(495)	(2,018)	(3,010)
Recoveries	2,369	1,319	5,290	5,378
Ending balance	$ 18,438	$ 25,127	$ 18,438	25,127
PCD Loans | Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				19,001
PCD Loans | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 26,537