Allowance for Credit Losses (Non-Accrual Loans and Leases and Loans and Leases Past Due) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	$ 82,986	$ 84,187
Non-Accrual	32,412	26,244
Current & Other	22,556,057	21,085,253
Total Loans and Leases	22,671,455	21,195,684
GNMA Loans past due by 90 days, but not yet repurchased	2,600
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Current & Other		89,500
Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Allowance For Non-Accrual Credit Losses	7,100
Total Non-Accrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Non-Accrual	32,400
Greater than 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	24,823	19,560
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	15,760	22,322
Greater than 90 Days and Accruing
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	42,403	42,305
Commercial real estate | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	6,006	121
Non-Accrual	8,095	2,920
Current & Other	3,575,383	3,542,525
Total Loans and Leases	3,589,484	3,545,566
Commercial real estate | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	6,479	1,446
Non-Accrual	4,148	4,600
Current & Other	2,449,327	2,490,042
Total Loans and Leases	2,459,954	2,496,088
Commercial real estate | Multifamily, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Non-Accrual	599	0
Current & Other	3,466,230	3,514,774
Total Loans and Leases	3,466,829	3,514,774
Commercial real estate | Construction & development, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Non-Accrual	0	0
Current & Other	662,703	678,740
Total Loans and Leases	662,703	678,740
Commercial real estate | Residential development, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Non-Accrual	0	0
Current & Other	164,180	189,010
Total Loans and Leases	164,180	189,010
Commercial real estate | Greater than 30 to 59 Days Past Due | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	6,006	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	6,336	975
Commercial real estate | Greater than 30 to 59 Days Past Due | Multifamily, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Construction & development, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Residential development, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	142	470
Commercial real estate | 60 to 89 Days Past Due | Multifamily, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Construction & development, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Residential development, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | Greater than 90 Days and Accruing | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	121
Commercial real estate | Greater than 90 Days and Accruing | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1	1
Commercial real estate | Greater than 90 Days and Accruing | Multifamily, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | Greater than 90 Days and Accruing | Construction & development, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate | Greater than 90 Days and Accruing | Residential development, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial | Term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	97	517
Non-Accrual	11,027	3,458
Current & Other	4,253,968	2,228,842
Total Loans and Leases	4,265,092	2,232,817
Commercial | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	3,960	3,960
Non-Accrual	763	767
Current & Other	935,720	1,207,666
Total Loans and Leases	940,443	1,212,393
Commercial | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	15,785	24,947
Non-Accrual	7,780	14,499
Current & Other	1,498,804	1,426,043
Total Loans and Leases	1,522,369	1,465,489
Commercial | Greater than 30 to 59 Days Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	94	136
Commercial | Greater than 30 to 59 Days Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	3,766	3,548
Commercial | Greater than 30 to 59 Days Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	4,177	10,685
Commercial | 60 to 89 Days Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	381
Commercial | 60 to 89 Days Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	193	376
Commercial | 60 to 89 Days Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	10,774	11,176
Commercial | Greater than 90 Days and Accruing | Term, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	3	0
Commercial | Greater than 90 Days and Accruing | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1	36
Commercial | Greater than 90 Days and Accruing | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	834	3,086
Residential | Mortgage, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	45,131	44,746
Non-Accrual	0	0
Current & Other	4,011,457	4,170,678
Total Loans and Leases	4,056,588	4,215,424
Residential | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	3,529	4,844
Non-Accrual	0	0
Current & Other	1,185,899	1,232,668
Total Loans and Leases	1,189,428	1,237,512
Residential | Greater than 30 to 59 Days Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,965	0
Residential | Greater than 30 to 59 Days Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,411	2,173
Residential | 60 to 89 Days Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	3,438	8,104
Residential | 60 to 89 Days Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	643	867
Residential | Greater than 90 Days and Accruing | Mortgage, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	39,728	36,642
Residential | Greater than 90 Days and Accruing | Mortgage, net | GNMA Loans
Financing Receivable, Past Due [Line Items]
GNMA Loans past due by 90 days, but not yet repurchased	2,600	4,300
Residential | Greater than 90 Days and Accruing | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,475	1,804
Consumer & Other
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,999	3,606
Non-Accrual	0	0
Current & Other	352,386	404,265
Total Loans and Leases	354,385	407,871
Consumer & Other | Greater than 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,068	2,043
Consumer & Other | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	570	948
Consumer & Other | Greater than 90 Days and Accruing
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	$ 361	$ 615