Allowance for Credit Losses (Non-Accrual Loans and Leases and Loans and Leases Past Due) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	$ 21,969,940	$ 21,779,367
Non-Accrual	24,152	31,076
Loans and leases (at fair value: $353,912 and $0)	21,969,940	21,779,367
Allowance for credit loss on non-accrual loans	7,300	16,700
Loans Deferred Under CARES Act	132,500	355,500
Greater than 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	24,349	24,791
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	16,977	47,256
Greater than 90 Days and Accruing
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	27,490	36,361
Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	68,816	108,408
Current and Other
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	21,876,972	21,639,883
Commercial real estate
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	10,765,052	10,210,182
Commercial real estate | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3,561,764	3,505,802
Non-Accrual	3,417	3,809
Commercial real estate | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2,330,338	2,333,945
Non-Accrual	2,535	5,984
Commercial real estate | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3,813,024	3,349,196
Non-Accrual	0	0
Commercial real estate | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	882,778	828,478
Non-Accrual	0	0
Commercial real estate | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	177,148	192,761
Non-Accrual	0	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,750	1,214
Commercial real estate | Greater than 30 to 59 Days Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,416	182
Commercial real estate | Greater than 30 to 59 Days Past Due | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	9,389	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	3,991
Commercial real estate | Greater than 30 to 59 Days Past Due | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	0
Commercial real estate | 60 to 89 Days Past Due | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	21,309
Commercial real estate | 60 to 89 Days Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	343	103
Commercial real estate | 60 to 89 Days Past Due | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	215
Commercial real estate | 60 to 89 Days Past Due | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	0
Commercial real estate | 60 to 89 Days Past Due | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	0
Commercial real estate | Greater than 90 Days and Accruing | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	815
Commercial real estate | Greater than 90 Days and Accruing | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1	208
Commercial real estate | Greater than 90 Days and Accruing | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	0
Commercial real estate | Greater than 90 Days and Accruing | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	0
Commercial real estate | Greater than 90 Days and Accruing | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	0
Commercial real estate | Total Past Due | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,750	23,338
Commercial real estate | Total Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,760	493
Commercial real estate | Total Past Due | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	9,389	215
Commercial real estate | Total Past Due | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	3,991
Commercial real estate | Total Past Due | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	0	0
Commercial real estate | Current and Other | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3,556,597	3,478,655
Commercial real estate | Current and Other | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2,326,043	2,327,468
Commercial real estate | Current and Other | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3,803,635	3,348,981
Commercial real estate | Current and Other | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	882,778	824,487
Commercial real estate | Current and Other | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	177,148	192,761
Commercial
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	5,547,064	6,343,857
Commercial | Term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3,159,466	4,024,467
Non-Accrual	5,511	2,205
Commercial | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	930,350	862,760
Non-Accrual	930	336
Commercial | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,457,248	1,456,630
Non-Accrual	11,759	18,742
Commercial | Greater than 30 to 59 Days Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	211	562
Commercial | Greater than 30 to 59 Days Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	501	1,491
Commercial | Greater than 30 to 59 Days Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	8,502	14,242
Commercial | 60 to 89 Days Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	82	0
Commercial | 60 to 89 Days Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	5,820	2,667
Commercial | 60 to 89 Days Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	7,347	18,220
Commercial | Greater than 90 Days and Accruing | Term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2	4
Commercial | Greater than 90 Days and Accruing | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3	7
Commercial | Greater than 90 Days and Accruing | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2,449	4,796
Commercial | Total Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	295	566
Commercial | Total Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	6,324	4,165
Commercial | Total Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	18,298	37,258
Commercial | Current and Other | Term, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3,153,660	4,021,696
Commercial | Current and Other | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	923,096	858,259
Commercial | Current and Other | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,427,191	1,400,630
Residential
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	5,464,683	5,007,970
Residential | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	4,330,860	3,871,906
Non-Accrual	0	0
Residential | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,133,823	1,136,064
Non-Accrual	0	0
Residential | Greater than 30 to 59 Days Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	943	1,587
Residential | Greater than 30 to 59 Days Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,182	844
Residential | 60 to 89 Days Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2,728	3,912
Residential | 60 to 89 Days Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	414	544
Residential | Greater than 90 Days and Accruing | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	23,957	27,713
Residential | Greater than 90 Days and Accruing | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	962	2,463
Residential | Total Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	27,628	33,212
Residential | Total Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2,558	3,851
Residential | Current and Other | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	4,303,232	3,838,694
Residential | Current and Other | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,131,265	1,132,213
Consumer & Other
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	193,141	217,358
Non-Accrual	0	0
Consumer & Other | Greater than 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	455	678
Consumer & Other | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	243	286
Consumer & Other | Greater than 90 Days and Accruing
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	116	355
Consumer & Other | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	814	1,319
Consumer & Other | Current and Other
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	$ 192,327	$ 216,039