Allowance for Loan and Lease Loss and Credit Quality (Non-Accrual Loans and Leases and Loans and Leases Past Due) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 81,766	$ 82,734
Non-Accrual	35,022	50,823
Current	20,836,583	20,289,109
Total, non-covered loans and leases	20,953,371	20,422,666
GNMA Loans past due by 90 days, but not yet repurchased	5,400
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	113,600	134,500
Greater than 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	18,927	19,766
60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	21,692	17,607
90 Days and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	41,147	45,361
Commercial real estate | Non-owner occupied term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	142	2,234
Non-Accrual	9,170	10,033
Current	3,527,772	3,560,798
Total, non-covered loans and leases	3,537,084	3,573,065
Commercial real estate | Owner occupied term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,361	5,293
Non-Accrual	7,502	8,682
Current	2,387,811	2,466,396
Total, non-covered loans and leases	2,396,674	2,480,371
Commercial real estate | Multifamily, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	107
Non-Accrual	0	4,298
Current	3,341,547	3,300,358
Total, non-covered loans and leases	3,341,547	3,304,763
Commercial real estate | Construction & development, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,601	0
Non-Accrual	0	0
Current	731,331	736,254
Total, non-covered loans and leases	732,932	736,254
Commercial real estate | Residential development, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual	0	0
Current	199,421	196,890
Total, non-covered loans and leases	199,421	196,890
Commercial real estate | Greater than 30 to 59 Days Past Due | Non-owner occupied term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	74	1,192
Commercial real estate | Greater than 30 to 59 Days Past Due | Owner occupied term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	663	3,920
Commercial real estate | Greater than 30 to 59 Days Past Due | Multifamily, net
Financing Receivable, Recorded Investment, 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, Recorded Investment, Past Due [Line Items]
Total Past Due	1,601	0
Commercial real estate | Greater than 30 to 59 Days Past Due | Residential development, net
Financing Receivable, Recorded Investment, 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, Recorded Investment, Past Due [Line Items]
Total Past Due	68	1,042
Commercial real estate | 60 to 89 Days Past Due | Owner occupied term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	698	1,372
Commercial real estate | 60 to 89 Days Past Due | Multifamily, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Construction & development, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 60 to 89 Days Past Due | Residential development, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 90 Days and Accruing | Non-owner occupied term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 90 Days and Accruing | Owner occupied term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	1
Commercial real estate | 90 Days and Accruing | Multifamily, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 90 Days and Accruing | Construction & development, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate | 90 Days and Accruing | Residential development, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | Term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	943	1,109
Non-Accrual	3,348	11,772
Current	2,267,055	2,220,042
Total, non-covered loans and leases	2,271,346	2,232,923
Commercial | Lines of credit & other, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	8,430	1,512
Non-Accrual	1,519	2,275
Current	1,270,638	1,165,738
Total, non-covered loans and leases	1,280,587	1,169,525
Commercial | Leases & equipment finance, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	18,481	20,341
Non-Accrual	13,483	13,763
Current	1,417,615	1,296,051
Total, non-covered loans and leases	1,449,579	1,330,155
Commercial | Greater than 30 to 59 Days Past Due | Term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	486	992
Commercial | Greater than 30 to 59 Days Past Due | Lines of credit & other, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,740	1,286
Commercial | Greater than 30 to 59 Days Past Due | Leases & equipment finance, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,813	8,571
Commercial | 60 to 89 Days Past Due | Term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	457	117
Commercial | 60 to 89 Days Past Due | Lines of credit & other, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,690	143
Commercial | 60 to 89 Days Past Due | Leases & equipment finance, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	8,835	8,754
Commercial | 90 Days and Accruing | Term, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial | 90 Days and Accruing | Lines of credit & other, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	83
Commercial | 90 Days and Accruing | Leases & equipment finance, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,833	3,016
Residential | Mortgage, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	43,123	44,118
Non-Accrual	0	0
Current	3,952,520	3,590,955
Total, non-covered loans and leases	3,995,643	3,635,073
Residential | Home equity loans & lines, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,938	3,847
Non-Accrual	0	0
Current	1,211,277	1,172,630
Total, non-covered loans and leases	1,215,215	1,176,477
Residential | Greater than 30 to 59 Days Past Due | Mortgage, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	25	0
Residential | Greater than 30 to 59 Days Past Due | Home equity loans & lines, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,150	987
Residential | 60 to 89 Days Past Due | Mortgage, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,414	4,900
Residential | 60 to 89 Days Past Due | Home equity loans & lines, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	582	368
Residential | 90 Days and Accruing | Mortgage, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	35,684	39,218
Residential | 90 Days and Accruing | Mortgage, net | GNMA Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
GNMA Loans past due by 90 days, but not yet repurchased	5,400	8,900
Residential | 90 Days and Accruing | Home equity loans & lines, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,206	2,492
Consumer & other, net
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,747	4,173
Non-Accrual	0	0
Current	529,596	582,997
Total, non-covered loans and leases	533,343	587,170
Consumer & other, net | Greater than 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,375	2,711
Consumer & other, net | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	948	911
Consumer & other, net | 90 Days and Accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 424	$ 551