Loans, Impaired Loans Recorded Investment, Unpaid Principal Balance, Related Allowance, Average Recorded Investment, and Interest Income Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	$ 247,575	$ 316,735
Unpaid Principal Balance	275,814	349,045
Related Allowance	25,846	35,054
Average Recorded Investment	236,860	333,439
Interest Income Recognized	$ 8,051	$ 8,784
Net Recorded Investment of the Impaired Loans	80.00%	81.00%
Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	$ 175,681	$ 182,587
Unpaid Principal Balance	181,002	191,333
Related Allowance	25,846	35,054
Average Recorded Investment	140,098	192,891
Interest Income Recognized	7,254	6,939
Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	71,894	134,148
Unpaid Principal Balance	94,812	157,712
Related Allowance	0	0
Average Recorded Investment	96,762	140,548
Interest Income Recognized	797	1,845
Commercial and industrial
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	142,244	213,271
Unpaid Principal Balance	166,418	240,038
Related Allowance	10,838	21,047
Average Recorded Investment	147,769	222,788
Interest Income Recognized	3,121	3,864
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	81,649	99,786
Unpaid Principal Balance	83,579	105,175
Related Allowance	10,838	21,047
Average Recorded Investment	58,494	104,808
Interest Income Recognized	2,629	2,345
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	60,595	113,485
Unpaid Principal Balance	82,839	134,863
Related Allowance	0	0
Average Recorded Investment	89,275	117,980
Interest Income Recognized	492	1,519
Commercial real estate — owner occupied
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	26,234	13,983
Unpaid Principal Balance	26,766	14,834
Related Allowance	2,973	23
Average Recorded Investment	14,072	14,599
Interest Income Recognized	772	401
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	23,796	5,544
Unpaid Principal Balance	23,937	5,568
Related Allowance	2,973	23
Average Recorded Investment	12,124	5,840
Interest Income Recognized	736	263
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	2,438	8,439
Unpaid Principal Balance	2,829	9,266
Related Allowance	0	0
Average Recorded Investment	1,948	8,759
Interest Income Recognized	36	138
Commercial and business lending
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	168,478	227,254
Unpaid Principal Balance	193,184	254,872
Related Allowance	13,811	21,070
Average Recorded Investment	161,841	237,387
Interest Income Recognized	3,893	4,265
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	105,445	105,330
Unpaid Principal Balance	107,516	110,743
Related Allowance	13,811	21,070
Average Recorded Investment	70,618	110,648
Interest Income Recognized	3,365	2,608
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	63,033	121,924
Unpaid Principal Balance	85,668	144,129
Related Allowance	0	0
Average Recorded Investment	91,223	126,739
Interest Income Recognized	528	1,657
Commercial real estate — investor
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	19,118	32,908
Unpaid Principal Balance	19,157	33,509
Related Allowance	1,597	3,410
Average Recorded Investment	16,924	37,757
Interest Income Recognized	1,739	2,120
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	17,823	26,764
Unpaid Principal Balance	17,862	27,031
Related Allowance	1,597	3,410
Average Recorded Investment	16,924	30,665
Interest Income Recognized	1,694	2,120
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	1,295	6,144
Unpaid Principal Balance	1,295	6,478
Related Allowance	0	0
Average Recorded Investment	0	7,092
Interest Income Recognized	45	0
Real estate construction
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	467	509
Unpaid Principal Balance	578	648
Related Allowance	86	84
Average Recorded Investment	484	529
Interest Income Recognized	29	31
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	467	509
Unpaid Principal Balance	578	648
Related Allowance	86	84
Average Recorded Investment	484	529
Interest Income Recognized	29	31
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	19,585	33,417
Unpaid Principal Balance	19,735	34,157
Related Allowance	1,683	3,494
Average Recorded Investment	17,408	38,286
Interest Income Recognized	1,768	2,151
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	18,290	27,273
Unpaid Principal Balance	18,440	27,679
Related Allowance	1,683	3,494
Average Recorded Investment	17,408	31,194
Interest Income Recognized	1,723	2,151
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	1,295	6,144
Unpaid Principal Balance	1,295	6,478
Related Allowance	0	0
Average Recorded Investment	0	7,092
Interest Income Recognized	45	0
Total commercial
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	188,063	260,671
Unpaid Principal Balance	212,919	289,029
Related Allowance	15,494	24,564
Average Recorded Investment	179,249	275,673
Interest Income Recognized	5,661	6,416
Total commercial | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	123,735	132,603
Unpaid Principal Balance	125,956	138,422
Related Allowance	15,494	24,564
Average Recorded Investment	88,026	141,842
Interest Income Recognized	5,088	4,759
Total commercial | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	64,328	128,068
Unpaid Principal Balance	86,963	150,607
Related Allowance	0	0
Average Recorded Investment	91,223	133,831
Interest Income Recognized	573	1,657
Residential mortgage
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	47,486	43,876
Unpaid Principal Balance	50,126	46,977
Related Allowance	6,512	6,438
Average Recorded Investment	45,410	45,218
Interest Income Recognized	1,831	1,735
Residential mortgage | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	40,561	37,902
Unpaid Principal Balance	42,922	39,979
Related Allowance	6,512	6,438
Average Recorded Investment	40,411	38,608
Interest Income Recognized	1,614	1,551
Residential mortgage | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	6,925	5,974
Unpaid Principal Balance	7,204	6,998
Related Allowance	0	0
Average Recorded Investment	4,999	6,610
Interest Income Recognized	217	184
Home equity
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	10,891	11,176
Unpaid Principal Balance	11,631	12,016
Related Allowance	3,718	3,943
Average Recorded Investment	11,061	11,527
Interest Income Recognized	556	631
Home equity | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	10,250	11,070
Unpaid Principal Balance	10,986	11,909
Related Allowance	3,718	3,943
Average Recorded Investment	10,521	11,420
Interest Income Recognized	549	627
Home equity | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	641	106
Unpaid Principal Balance	645	107
Related Allowance	0	0
Average Recorded Investment	540	107
Interest Income Recognized	7	4
Other consumer
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,135	1,012
Unpaid Principal Balance	1,138	1,023
Related Allowance	122	109
Average Recorded Investment	1,140	1,021
Interest Income Recognized	3	2
Other consumer | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	1,135	1,012
Unpaid Principal Balance	1,138	1,023
Related Allowance	122	109
Average Recorded Investment	1,140	1,021
Interest Income Recognized	3	2
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	59,512	56,064
Unpaid Principal Balance	62,895	60,016
Related Allowance	10,352	10,490
Average Recorded Investment	57,611	57,766
Interest Income Recognized	2,390	2,368
Total consumer | Loans with a related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	51,946	49,984
Unpaid Principal Balance	55,046	52,911
Related Allowance	10,352	10,490
Average Recorded Investment	52,072	51,049
Interest Income Recognized	2,166	2,180
Total consumer | Loans with no related allowance
Summarize of nonaccrual loans, accruing loans past due 90 days or more, and restructured loans
Recorded Investment	7,566	6,080
Unpaid Principal Balance	7,849	7,105
Related Allowance	0	0
Average Recorded Investment	5,539	6,717
Interest Income Recognized	$ 224	$ 188