Allowance for Credit Losses (Non-Accrual Loans and Leases and Loans and Leases Past Due) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 112,475	$ 84,187
Non-Accrual	39,128	26,244
Current & Other	21,099,875	21,085,253
Total Loans and Leases	21,251,478	21,195,684
GNMA Loans past due by 90 days, but not yet repurchased	5,300
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	11,600
Amortized cost basis of lease and equipment finance on Non-Accrual	13,000
Greater than 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	42,745	19,560
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	17,217	22,322
90+ Days and Accruing
Financing Receivable, Past Due [Line Items]
Total Past Due	52,513	42,305
Commercial real estate | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	9,732	121
Non-Accrual	4,510	2,920
Current & Other	3,599,178	3,542,525
Total Loans and Leases	3,613,420	3,545,566
Commercial real estate | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	13,472	1,446
Non-Accrual	6,135	4,600
Current & Other	2,452,580	2,490,042
Total Loans and Leases	2,472,187	2,496,088
Commercial real estate | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual	598	0
Current & Other	3,463,619	3,514,774
Total Loans and Leases	3,464,217	3,514,774
Commercial real estate | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual	0	0
Current & Other	667,975	678,740
Total Loans and Leases	667,975	678,740
Commercial real estate | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual	0	0
Current & Other	187,594	189,010
Total Loans and Leases	187,594	189,010
Commercial real estate | Greater than 30 to 59 Days Past Due | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	4,331	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	7,064	975
Commercial real estate | Greater than 30 to 59 Days Past Due | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	5,401	0
Commercial real estate | 60 to 89 Days Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	4,231	470
Commercial real estate | 60 to 89 Days Past Due | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 90+ Days and Accruing | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	121
Commercial real estate | 90+ Days and Accruing | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	2,177	1
Commercial real estate | 90+ Days and Accruing | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 90+ Days and Accruing | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 90+ Days and Accruing | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial | Term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,970	517
Non-Accrual	2,407	3,458
Current & Other	2,313,196	2,228,842
Total Loans and Leases	2,317,573	2,232,817
Commercial | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	3,843	3,960
Non-Accrual	12,443	767
Current & Other	1,191,765	1,207,666
Total Loans and Leases	1,208,051	1,212,393
Commercial | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Past Due	18,612	24,947
Non-Accrual	13,035	14,499
Current & Other	1,461,115	1,426,043
Total Loans and Leases	1,492,762	1,465,489
Commercial | Greater than 30 to 59 Days Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	316	136
Commercial | Greater than 30 to 59 Days Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	3,194	3,548
Commercial | Greater than 30 to 59 Days Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Past Due	12,668	10,685
Commercial | 60 to 89 Days Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,441	381
Commercial | 60 to 89 Days Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	648	376
Commercial | 60 to 89 Days Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Past Due	3,663	11,176
Commercial | 90+ Days and Accruing | Term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	213	0
Commercial | 90+ Days and Accruing | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1	36
Commercial | 90+ Days and Accruing | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Past Due	2,281	3,086
Residential | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Past Due	55,282	44,746
Non-Accrual	0	0
Current & Other	4,138,626	4,170,678
Total Loans and Leases	4,193,908	4,215,424
Residential | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Past Due	5,537	4,844
Non-Accrual	0	0
Current & Other	1,243,615	1,232,668
Total Loans and Leases	1,249,152	1,237,512
Residential | Greater than 30 to 59 Days Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Past Due	9,472	0
Residential | Greater than 30 to 59 Days Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Past Due	3,081	2,173
Residential | 60 to 89 Days Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Past Due	163	8,104
Residential | 60 to 89 Days Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Past Due	728	867
Residential | 90+ Days and Accruing | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Past Due	45,647	36,642
Residential | 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	5,300	4,300
Residential | 90+ Days and Accruing | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,728	1,804
Consumer & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	4,027	3,606
Non-Accrual	0	0
Current & Other	380,612	404,265
Total Loans and Leases	384,639	407,871
Consumer & other, net | Greater than 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	2,619	2,043
Consumer & other, net | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	942	948
Consumer & other, net | 90+ Days and Accruing
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 466	$ 615