Loans, Impaired Loans Recorded Investment, Unpaid Principal Balance, Related Allowance, Average Recorded Investment, and Interest Income Recognized (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	$ 211,687	$ 247,575
Unpaid Principal Balance	233,765	275,814
Related Allowance	32,497	25,846
Average Recorded Investment	205,083	236,860
Interest Income Recognized	$ 2,760	$ 8,051
Net Recorded Investment of the Impaired Loans	77.00%	80.00%
Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	$ 157,951	$ 175,681
Unpaid Principal Balance	165,749	181,002
Related Allowance	32,497	25,846
Average Recorded Investment	152,073	140,098
Interest Income Recognized	2,882	7,254
Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	53,736	71,894
Unpaid Principal Balance	68,016	94,812
Related Allowance	0	0
Average Recorded Investment	53,010	96,762
Interest Income Recognized	122	797
Commercial and industrial
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	110,993	142,244
Unpaid Principal Balance	125,787	166,418
Related Allowance	17,628	10,838
Average Recorded Investment	109,283	147,769
Interest Income Recognized	439	3,121
Commercial and industrial | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	75,928	81,649
Unpaid Principal Balance	77,873	83,579
Related Allowance	17,628	10,838
Average Recorded Investment	70,082	58,494
Interest Income Recognized	725	2,629
Commercial and industrial | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	35,065	60,595
Unpaid Principal Balance	47,914	82,839
Related Allowance	0	0
Average Recorded Investment	39,201	89,275
Interest Income Recognized	286	492
Commercial real estate — owner occupied
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	20,255	26,234
Unpaid Principal Balance	21,773	26,766
Related Allowance	829	2,973
Average Recorded Investment	19,828	14,072
Interest Income Recognized	119	772
Commercial real estate — owner occupied | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	15,386	23,796
Unpaid Principal Balance	15,853	23,937
Related Allowance	829	2,973
Average Recorded Investment	15,649	12,124
Interest Income Recognized	95	736
Commercial real estate — owner occupied | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	4,869	2,438
Unpaid Principal Balance	5,920	2,829
Related Allowance	0	0
Average Recorded Investment	4,179	1,948
Interest Income Recognized	24	36
Commercial and business lending
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	131,248	168,478
Unpaid Principal Balance	147,560	193,184
Related Allowance	18,457	13,811
Average Recorded Investment	129,111	161,841
Interest Income Recognized	558	3,893
Commercial and business lending | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	91,314	105,445
Unpaid Principal Balance	93,726	107,516
Related Allowance	18,457	13,811
Average Recorded Investment	85,731	70,618
Interest Income Recognized	820	3,365
Commercial and business lending | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	39,934	63,033
Unpaid Principal Balance	53,834	85,668
Related Allowance	0	0
Average Recorded Investment	43,380	91,223
Interest Income Recognized	262	528
Commercial real estate — investor
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	16,381	19,118
Unpaid Principal Balance	16,500	19,157
Related Allowance	4,132	1,597
Average Recorded Investment	16,491	16,924
Interest Income Recognized	901	1,739
Commercial real estate — investor | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	15,397	17,823
Unpaid Principal Balance	15,469	17,862
Related Allowance	4,132	1,597
Average Recorded Investment	15,485	16,924
Interest Income Recognized	901	1,694
Commercial real estate — investor | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	984	1,295
Unpaid Principal Balance	1,031	1,295
Related Allowance	0	0
Average Recorded Investment	1,006	0
Interest Income Recognized	0	45
Real estate construction
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	448	467
Unpaid Principal Balance	523	578
Related Allowance	77	86
Average Recorded Investment	456	484
Interest Income Recognized	15	29
Real estate construction | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	448	467
Unpaid Principal Balance	523	578
Related Allowance	77	86
Average Recorded Investment	456	484
Interest Income Recognized	15	29
Real estate construction | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Commercial real estate lending
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	16,829	19,585
Unpaid Principal Balance	17,023	19,735
Related Allowance	4,209	1,683
Average Recorded Investment	16,947	17,408
Interest Income Recognized	916	1,768
Commercial real estate lending | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	15,845	18,290
Unpaid Principal Balance	15,992	18,440
Related Allowance	4,209	1,683
Average Recorded Investment	15,941	17,408
Interest Income Recognized	916	1,723
Commercial real estate lending | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	984	1,295
Unpaid Principal Balance	1,031	1,295
Related Allowance	0	0
Average Recorded Investment	1,006	0
Interest Income Recognized	0	45
Total commercial
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	148,077	188,063
Unpaid Principal Balance	164,583	212,919
Related Allowance	22,666	15,494
Average Recorded Investment	146,058	179,249
Interest Income Recognized	1,474	5,661
Total commercial | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	107,159	123,735
Unpaid Principal Balance	109,718	125,956
Related Allowance	22,666	15,494
Average Recorded Investment	101,672	88,026
Interest Income Recognized	1,736	5,088
Total commercial | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	40,918	64,328
Unpaid Principal Balance	54,865	86,963
Related Allowance	0	0
Average Recorded Investment	44,386	91,223
Interest Income Recognized	262	573
Residential mortgage
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	51,469	47,486
Unpaid Principal Balance	56,033	50,126
Related Allowance	6,208	6,512
Average Recorded Investment	47,272	45,410
Interest Income Recognized	991	1,831
Residential mortgage | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	39,926	40,561
Unpaid Principal Balance	44,171	42,922
Related Allowance	6,208	6,512
Average Recorded Investment	39,433	40,411
Interest Income Recognized	863	1,614
Residential mortgage | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	11,543	6,925
Unpaid Principal Balance	11,862	7,204
Related Allowance	0	0
Average Recorded Investment	7,839	4,999
Interest Income Recognized	128	217
Home equity
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	11,092	10,891
Unpaid Principal Balance	12,098	11,631
Related Allowance	3,514	3,718
Average Recorded Investment	10,702	11,061
Interest Income Recognized	294	556
Home equity | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	9,817	10,250
Unpaid Principal Balance	10,809	10,986
Related Allowance	3,514	3,718
Average Recorded Investment	9,917	10,521
Interest Income Recognized	282	549
Home equity | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,275	641
Unpaid Principal Balance	1,289	645
Related Allowance	0	0
Average Recorded Investment	785	540
Interest Income Recognized	12	7
Other consumer
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,049	1,135
Unpaid Principal Balance	1,051	1,138
Related Allowance	109	122
Average Recorded Investment	1,051	1,140
Interest Income Recognized	1	3
Other consumer | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,049	1,135
Unpaid Principal Balance	1,051	1,138
Related Allowance	109	122
Average Recorded Investment	1,051	1,140
Interest Income Recognized	1	3
Other consumer | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Total consumer
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	63,610	59,512
Unpaid Principal Balance	69,182	62,895
Related Allowance	9,831	10,352
Average Recorded Investment	59,025	57,611
Interest Income Recognized	1,286	2,390
Total consumer | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	50,792	51,946
Unpaid Principal Balance	56,031	55,046
Related Allowance	9,831	10,352
Average Recorded Investment	50,401	52,072
Interest Income Recognized	1,146	2,166
Total consumer | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	12,818	7,566
Unpaid Principal Balance	13,151	7,849
Related Allowance	0	0
Average Recorded Investment	8,624	5,539
Interest Income Recognized	$ 140	$ 224