Allowance for Credit Losses (Allowance for Credit Losses Methodology) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Allowance for credit losses on loans and leases
Balance, beginning of period	$ 311,283	$ 291,420	$ 328,401	$ 157,629
Provision for credit losses for loans and leases	(17,775)	81,484	(17,249)	186,986
Charge-offs	(17,079)	(19,453)	(37,994)	(43,908)
Recoveries	3,458	3,294	6,729	6,039
Net (charge-offs) recoveries	(13,621)	(16,159)	(31,265)	(37,869)
Balance, end of period	279,887	356,745	279,887	356,745
Reserve for unfunded commitments
Balance, beginning of period	19,760	20,927	20,286	5,106
Provision for credit losses on unfunded commitments	(5,221)	5,441	(5,747)	18,024
Balance, end of period	14,539	26,368	14,539	26,368
Total allowance for credit losses	294,426	383,113	294,426	383,113
Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses on loans and leases
Balance, beginning of period				49,999
Reserve for unfunded commitments
Balance, beginning of period				3,238
Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses on loans and leases
Balance, beginning of period				207,628
Reserve for unfunded commitments
Balance, beginning of period				8,344
Commercial real estate
Allowance for credit losses on loans and leases
Balance, beginning of period	154,475	99,778	141,710	50,847
Provision for credit losses for loans and leases	(25,484)	52,890	(13,058)	96,498
Charge-offs	(129)	0	(170)	0
Recoveries	89	160	469	406
Net (charge-offs) recoveries	(40)	160	299	406
Balance, end of period	128,951	152,828	128,951	152,828
Reserve for unfunded commitments
Balance, beginning of period	15,668	15,760	15,360	534
Provision for credit losses on unfunded commitments	(5,574)	5,048	(5,266)	16,244
Balance, end of period	10,094	20,808	10,094	20,808
Total allowance for credit losses	139,045	173,636	139,045	173,636
Commercial real estate | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses on loans and leases
Balance, beginning of period				5,077
Reserve for unfunded commitments
Balance, beginning of period				4,030
Commercial real estate | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses on loans and leases
Balance, beginning of period				55,924
Reserve for unfunded commitments
Balance, beginning of period				4,564
Commercial
Allowance for credit losses on loans and leases
Balance, beginning of period	128,838	146,607	150,864	73,820
Provision for credit losses for loans and leases	5,964	21,301	1,461	70,974
Charge-offs	(16,093)	(17,549)	(35,707)	(40,157)
Recoveries	2,681	2,256	4,772	3,969
Net (charge-offs) recoveries	(13,412)	(15,293)	(30,935)	(36,188)
Balance, end of period	121,390	152,615	121,390	152,615
Reserve for unfunded commitments
Balance, beginning of period	1,801	2,927	2,190	2,539
Provision for credit losses on unfunded commitments	344	(6)	(45)	869
Balance, end of period	2,145	2,921	2,145	2,921
Total allowance for credit losses	123,535	155,536	123,535	155,536
Commercial | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses on loans and leases
Balance, beginning of period				44,009
Reserve for unfunded commitments
Balance, beginning of period				(487)
Commercial | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses on loans and leases
Balance, beginning of period				117,829
Reserve for unfunded commitments
Balance, beginning of period				2,052
Residential
Allowance for credit losses on loans and leases
Balance, beginning of period	21,090	34,251	27,964	24,714
Provision for credit losses for loans and leases	3,997	6,157	(2,915)	13,342
Charge-offs	0	(143)	(70)	(154)
Recoveries	209	283	317	547
Net (charge-offs) recoveries	209	140	247	393
Balance, end of period	25,296	40,548	25,296	40,548
Reserve for unfunded commitments
Balance, beginning of period	1,288	1,741	1,661	149
Provision for credit losses on unfunded commitments	422	320	49	645
Balance, end of period	1,710	2,061	1,710	2,061
Total allowance for credit losses	27,006	42,609	27,006	42,609
Residential | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses on loans and leases
Balance, beginning of period				2,099
Reserve for unfunded commitments
Balance, beginning of period				1,267
Residential | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses on loans and leases
Balance, beginning of period				26,813
Reserve for unfunded commitments
Balance, beginning of period				1,416
Consumer & Other
Allowance for credit losses on loans and leases
Balance, beginning of period	6,880	10,784	7,863	8,248
Provision for credit losses for loans and leases	(2,252)	1,136	(2,737)	6,172
Charge-offs	(857)	(1,761)	(2,047)	(3,597)
Recoveries	479	595	1,171	1,117
Net (charge-offs) recoveries	(378)	(1,166)	(876)	(2,480)
Balance, end of period	4,250	10,754	4,250	10,754
Reserve for unfunded commitments
Balance, beginning of period	1,003	499	1,075	1,884
Provision for credit losses on unfunded commitments	(413)	79	(485)	266
Balance, end of period	590	578	590	578
Total allowance for credit losses	$ 4,840	$ 11,332	$ 4,840	11,332
Consumer & Other | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses on loans and leases
Balance, beginning of period				(1,186)
Reserve for unfunded commitments
Balance, beginning of period				(1,572)
Consumer & Other | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses on loans and leases
Balance, beginning of period				7,062
Reserve for unfunded commitments
Balance, beginning of period				$ 312