Allowance for Loan and Lease Loss and Credit Quality (Non-Accrual Loans and Leases and Loans and Leases Past Due) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 85,362	$ 82,734
Non-Accrual	31,636	50,823
Current & Other	21,403,796	20,289,109
Total Loans and Leases	21,520,794	20,422,666
GNMA Loans past due by 90 days, but not yet repurchased	5,200
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Past Due [Line Items]
Current & Other	104,800	134,500
Greater than 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	17,538	19,766
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	26,852	17,607
90+ Days and Accruing
Financing Receivable, Past Due [Line Items]
Total Past Due	40,972	45,361
Commercial real estate | Non-owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,710	2,234
Non-Accrual	9,677	10,033
Current & Other	3,484,168	3,560,798
Total Loans and Leases	3,495,555	3,573,065
Commercial real estate | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	8,194	5,293
Non-Accrual	5,609	8,682
Current & Other	2,552,496	2,466,396
Total Loans and Leases	2,566,299	2,480,371
Commercial real estate | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	107
Non-Accrual	0	4,298
Current & Other	3,479,986	3,300,358
Total Loans and Leases	3,479,986	3,304,763
Commercial real estate | Construction & development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual	0	0
Current & Other	771,214	736,254
Total Loans and Leases	771,214	736,254
Commercial real estate | Residential development, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual	0	0
Current & Other	191,500	196,890
Total Loans and Leases	191,500	196,890
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	20	1,192
Commercial real estate | Greater than 30 to 59 Days Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	4,131	3,920
Commercial real estate | Greater than 30 to 59 Days Past Due | Multifamily, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	107
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	1,690	1,042
Commercial real estate | 60 to 89 Days Past Due | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	4,062	1,372
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	0
Commercial real estate | 90+ Days and Accruing | Owner occupied term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1	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	1,477	1,109
Non-Accrual	2,763	11,772
Current & Other	2,306,519	2,220,042
Total Loans and Leases	2,310,759	2,232,923
Commercial | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	2,720	1,512
Non-Accrual	1,048	2,275
Current & Other	1,250,987	1,165,738
Total Loans and Leases	1,254,755	1,169,525
Commercial | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Past Due	20,426	20,341
Non-Accrual	12,539	13,763
Current & Other	1,452,788	1,296,051
Total Loans and Leases	1,485,753	1,330,155
Commercial | Greater than 30 to 59 Days Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	465	992
Commercial | Greater than 30 to 59 Days Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,961	1,286
Commercial | Greater than 30 to 59 Days Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Past Due	7,199	8,571
Commercial | 60 to 89 Days Past Due | Term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,012	117
Commercial | 60 to 89 Days Past Due | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	533	143
Commercial | 60 to 89 Days Past Due | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Past Due	9,906	8,754
Commercial | 90+ Days and Accruing | Term, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial | 90+ Days and Accruing | Lines of credit & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	226	83
Commercial | 90+ Days and Accruing | Leases & equipment finance, net
Financing Receivable, Past Due [Line Items]
Total Past Due	3,321	3,016
Residential | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Past Due	43,099	44,118
Non-Accrual	0	0
Current & Other	4,202,575	3,590,955
Total Loans and Leases	4,245,674	3,635,073
Residential | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Past Due	3,658	3,847
Non-Accrual	0	0
Current & Other	1,220,920	1,172,630
Total Loans and Leases	1,224,578	1,176,477
Residential | Greater than 30 to 59 Days Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Residential | Greater than 30 to 59 Days Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,317	987
Residential | 60 to 89 Days Past Due | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Past Due	7,698	4,900
Residential | 60 to 89 Days Past Due | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,109	368
Residential | 90+ Days and Accruing | Mortgage, net
Financing Receivable, Past Due [Line Items]
Total Past Due	35,401	39,218
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	5,200	8,900
Residential | 90+ Days and Accruing | Home equity loans & lines, net
Financing Receivable, Past Due [Line Items]
Total Past Due	1,232	2,492
Consumer & other, net
Financing Receivable, Past Due [Line Items]
Total Past Due	4,078	4,173
Non-Accrual	0	0
Current & Other	490,643	582,997
Total Loans and Leases	494,721	587,170
Consumer & other, net | Greater than 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	2,445	2,711
Consumer & other, net | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due	842	911
Consumer & other, net | 90+ Days and Accruing
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 791	$ 551