Allowance for Loan and Lease Loss and Credit Quality (Internal Risk Rating By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	$ 19,854,033	$ 19,019,192
GNMA Loans, right to repurchase	8,000
Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	$ 19,493,451	$ 18,641,414
Percentage of impaired loans	3.10%	1.70%
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	$ 159,540	$ 131,150
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	$ 137,530	$ 166,246
Percentage of impaired loans	96.90%	98.30%
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	$ 15,855	$ 14,070
Loss
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	4,114	6,399
Impaired
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	43,543	59,913
Commercial real estate | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,527,357	3,483,197
Commercial real estate | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,474,845	2,476,654
Commercial real estate | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,225,538	3,060,616
Commercial real estate | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	646,684	540,696
Commercial real estate | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	198,518	165,941
Commercial real estate | Pass/Watch | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,459,769	3,388,421
Commercial real estate | Pass/Watch | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,414,053	2,398,215
Commercial real estate | Pass/Watch | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,205,253	3,037,320
Commercial real estate | Pass/Watch | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	644,735	538,515
Commercial real estate | Pass/Watch | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	198,518	165,502
Commercial real estate | Special Mention | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	27,270	45,189
Commercial real estate | Special Mention | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	25,237	30,343
Commercial real estate | Special Mention | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	11,427	13,783
Commercial real estate | Special Mention | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Special Mention | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Substandard | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	26,306	33,026
Commercial real estate | Substandard | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	27,934	34,743
Commercial real estate | Substandard | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	4,564	5,639
Commercial real estate | Substandard | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,949	2,181
Commercial real estate | Substandard | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	439
Commercial real estate | Doubtful | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	122	630
Commercial real estate | Doubtful | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	49	438
Commercial real estate | Doubtful | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Doubtful | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Doubtful | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Loss | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	216	78
Commercial real estate | Loss | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	130	706
Commercial real estate | Loss | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Loss | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Loss | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Impaired | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	13,674	15,853
Commercial real estate | Impaired | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	7,442	12,209
Commercial real estate | Impaired | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	4,294	3,874
Commercial real estate | Impaired | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial real estate | Impaired | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Commercial | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,149,376	1,944,925
Commercial | Lines of credit & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,133,508	1,166,275
Commercial | Leases & equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,282,128	1,167,503
Commercial | Pass/Watch | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,107,781	1,900,062
Commercial | Pass/Watch | Lines of credit & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,051,849	1,122,360
Commercial | Pass/Watch | Leases & equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,248,631	1,134,446
Commercial | Special Mention | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	19,513	12,735
Commercial | Special Mention | Lines of credit & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	56,191	6,539
Commercial | Special Mention | Leases & equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	7,037	8,494
Commercial | Substandard | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	7,724	10,372
Commercial | Substandard | Lines of credit & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	22,344	30,941
Commercial | Substandard | Leases & equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	7,967	10,133
Commercial | Doubtful | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	4	82
Commercial | Doubtful | Lines of credit & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2	52
Commercial | Doubtful | Leases & equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	15,678	12,868
Commercial | Loss | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	69	80
Commercial | Loss | Lines of credit & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	55	0
Commercial | Loss | Leases & equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,034	1,562
Commercial | Impaired | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	14,285	21,594
Commercial | Impaired | Lines of credit & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,067	6,383
Commercial | Impaired | Leases & equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	781	0
Residential | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,468,569	3,182,888
Residential | Mortgage, net | Financing Receivables, Equal to Greater than 90 Days Past Due | GNMA Loans
Financing Receivable, Recorded Investment [Line Items]
GNMA Loans, right to repurchase	8,000	12,400
Residential | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,143,351	1,097,877
Residential | Pass/Watch | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,424,259	3,136,071
Residential | Pass/Watch | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,139,111	1,092,496
Residential | Special Mention | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	6,497	7,505
Residential | Special Mention | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,486	2,564
Residential | Substandard | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	36,726	35,918
Residential | Substandard | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,258	2,286
Residential | Doubtful | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Residential | Doubtful | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Residential | Loss | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,087	3,394
Residential | Loss | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	496	531
Residential | Impaired | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Residential | Impaired | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Consumer & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	604,159	732,620
Consumer & other, net | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	599,492	728,006
Consumer & other, net | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,882	3,998
Consumer & other, net | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	758	568
Consumer & other, net | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Consumer & other, net | Loss
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	27	48
Consumer & other, net | Impaired
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	$ 0	$ 0