Allowance for Loan and Lease Loss and Credit Quality (Internal Risk Rating By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	$ 18,677,762	$ 17,508,663
Loans and leases	18,677,762	17,508,663	$ 17,392,051
GNMA Loans past due by 90 days, but not yet repurchased	12,300
Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	$ 18,270,401	$ 17,012,351
Percentage of impaired loans	5.80%	8.10%
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	$ 139,612	$ 183,632
Percentage of impaired loans	1.10%	6.50%
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	$ 179,436	$ 239,642
Percentage of impaired loans	93.10%	82.50%
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	$ 11,791	$ 12,214
Percentage of impaired loans		2.90%
Loss
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	3,565	$ 6,850
Impaired
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	72,957	53,974
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	9,644,507		9,339,002
Commercial real estate | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,475,243	3,330,442
Commercial real estate | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,467,995	2,599,055
Commercial real estate | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,993,203	2,858,956
Commercial real estate | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	521,666	463,625
Commercial real estate | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	186,400	142,984
Commercial real estate | Pass/Watch | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,381,062	3,205,241
Commercial real estate | Pass/Watch | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,374,238	2,466,247
Commercial real estate | Pass/Watch | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,963,655	2,828,370
Commercial real estate | Pass/Watch | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	516,139	458,328
Commercial real estate | Pass/Watch | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	178,239	134,491
Commercial real estate | Special Mention | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	40,560	55,194
Commercial real estate | Special Mention | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	43,483	75,189
Commercial real estate | Special Mention | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	16,695	11,903
Commercial real estate | Special Mention | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,934	1,712
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	34,711	48,699
Commercial real estate | Substandard | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	39,662	46,781
Commercial real estate | Substandard | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	8,968	14,687
Commercial real estate | Substandard | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,502	2,494
Commercial real estate | Substandard | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,188	1,189
Commercial real estate | Doubtful | Non-owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	282	1,368
Commercial real estate | Doubtful | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	972
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	0	546
Commercial real estate | Loss | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	357	1,653
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	18,628	19,394
Commercial real estate | Impaired | Owner occupied term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	10,255	8,213
Commercial real estate | Impaired | Multifamily, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,885	3,996
Commercial real estate | Impaired | Construction & development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,091	1,091
Commercial real estate | Impaired | Residential development, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	6,973	7,304
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	4,091,441		3,550,976
Commercial | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,819,664	1,508,780
Commercial | LOC & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,134,045	1,116,259
Commercial | Leases and equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,137,732	950,588
Commercial | Pass/Watch | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,773,745	1,458,699
Commercial | Pass/Watch | LOC & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,082,301	1,063,305
Commercial | Pass/Watch | Leases and equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,111,968	927,378
Commercial | Special Mention | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	9,176	15,716
Commercial | Special Mention | LOC & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	10,005	10,565
Commercial | Special Mention | Leases and equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	5,379	5,614
Commercial | Substandard | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	14,700	24,678
Commercial | Substandard | LOC & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	31,293	37,387
Commercial | Substandard | Leases and equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	8,072	6,866
Commercial | Doubtful | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	85	119
Commercial | Doubtful | LOC & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	276	3
Commercial | Doubtful | Leases and equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	11,148	9,752
Commercial | Loss | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3	347
Commercial | Loss | LOC & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	244
Commercial | Loss | Leases and equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,165	978
Commercial | Impaired | Term, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	21,955	9,221
Commercial | Impaired | LOC & other, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	10,170	4,755
Commercial | Impaired | Leases and equipment finance, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	0	0
Residential
Financing Receivable, Recorded Investment [Line Items]
Loans and leases	4,174,292		3,876,556
Residential | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,094,361	2,887,971
Residential | Mortgage, net | Financing Receivables, Equal to Greater than 90 Days Past Due | GNMA Loans
Financing Receivable, Recorded Investment [Line Items]
GNMA Loans past due by 90 days, but not yet repurchased	12,300	10,900
Residential | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,079,931	1,011,844
Residential | Pass/Watch | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,050,451	2,830,547
Residential | Pass/Watch | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	1,074,788	1,006,647
Residential | Special Mention | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	6,071	1,803
Residential | Special Mention | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,942	1,490
Residential | Substandard | Mortgage, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	35,919	53,607
Residential | Substandard | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	2,119	2,727
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	1,920	2,014
Residential | Loss | Home equity loans & lines, net
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	82	980
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	767,522	638,159
Loans and leases	767,522		$ 625,517
Consumer & other, net | Pass/Watch
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	763,815	633,098
Consumer & other, net | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	3,367	4,446
Consumer & other, net | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	302	527
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	38	88
Consumer & other, net | Impaired
Financing Receivable, Recorded Investment [Line Items]
Loans by credit quality	$ 0	$ 0