Allowance for Credit Losses (Allowance for Credit Losses Methodology) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Allowance for credit losses on loans and leases
Balance, beginning of period	$ 279,887	$ 356,745	$ 328,401	$ 157,629
Provision for credit losses for loans and leases	(16,132)	1,785	(33,381)	188,771
Charge-offs	(10,373)	(16,646)	(48,367)	(60,554)
Recoveries	4,178	3,165	10,907	9,204
Net (charge-offs) recoveries	(6,195)	(13,481)	(37,460)	(51,350)
Balance, end of period	257,560	345,049	257,560	345,049
Reserve for unfunded commitments
Balance, beginning of period	14,539	26,368	20,286	5,106
Provision (recapture) for credit losses on unfunded commitments	(2,787)	(2,062)	(8,534)	15,962
Balance, end of period	11,752	24,306	11,752	24,306
Total allowance for credit losses	269,312	369,355	269,312	369,355
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	128,951	152,828	141,710	50,847
Provision for credit losses for loans and leases	(20,141)	(18,834)	(33,199)	77,664
Charge-offs	(916)	0	(1,086)	0
Recoveries	120	61	589	467
Net (charge-offs) recoveries	(796)	61	(497)	467
Balance, end of period	108,014	134,055	108,014	134,055
Reserve for unfunded commitments
Balance, beginning of period	10,094	20,808	15,360	534
Provision (recapture) for credit losses on unfunded commitments	(3,273)	(380)	(8,539)	15,864
Balance, end of period	6,821	20,428	6,821	20,428
Total allowance for credit losses	114,835	154,483	114,835	154,483
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	121,390	152,615	150,864	73,820
Provision for credit losses for loans and leases	2,719	25,603	4,180	96,577
Charge-offs	(8,521)	(15,426)	(44,228)	(55,583)
Recoveries	3,346	2,044	8,118	6,013
Net (charge-offs) recoveries	(5,175)	(13,382)	(36,110)	(49,570)
Balance, end of period	118,934	164,836	118,934	164,836
Reserve for unfunded commitments
Balance, beginning of period	2,145	2,921	2,190	2,539
Provision (recapture) for credit losses on unfunded commitments	440	(1,198)	395	(329)
Balance, end of period	2,585	1,723	2,585	1,723
Total allowance for credit losses	121,519	166,559	121,519	166,559
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	25,296	40,548	27,964	24,714
Provision for credit losses for loans and leases	1,703	(5,641)	(1,212)	7,701
Charge-offs	0	(120)	(70)	(274)
Recoveries	281	407	598	954
Net (charge-offs) recoveries	281	287	528	680
Balance, end of period	27,280	35,194	27,280	35,194
Reserve for unfunded commitments
Balance, beginning of period	1,710	2,061	1,661	149
Provision (recapture) for credit losses on unfunded commitments	247	(542)	296	103
Balance, end of period	1,957	1,519	1,957	1,519
Total allowance for credit losses	29,237	36,713	29,237	36,713
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	4,250	10,754	7,863	8,248
Provision for credit losses for loans and leases	(413)	657	(3,150)	6,829
Charge-offs	(936)	(1,100)	(2,983)	(4,697)
Recoveries	431	653	1,602	1,770
Net (charge-offs) recoveries	(505)	(447)	(1,381)	(2,927)
Balance, end of period	3,332	10,964	3,332	10,964
Reserve for unfunded commitments
Balance, beginning of period	590	578	1,075	1,884
Provision (recapture) for credit losses on unfunded commitments	(201)	58	(686)	324
Balance, end of period	389	636	389	636
Total allowance for credit losses	$ 3,721	$ 11,600	$ 3,721	11,600
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