Loans, Impaired Loans Recorded Investment, Unpaid Principal Balance, Related Allowance, Average Recorded Investment, and Interest Income Recognized (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	$ 168,568	$ 247,575
Unpaid Principal Balance	202,895	275,814
Related Allowance	15,781	25,846
Average Recorded Investment	202,574	236,860
Interest Income Recognized	$ 3,774	$ 8,051
Net Recorded Investment of the Impaired Loans	75.00%	80.00%
Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	$ 115,865	$ 175,681
Unpaid Principal Balance	131,384	181,002
Related Allowance	15,781	25,846
Average Recorded Investment	153,802	140,098
Interest Income Recognized	3,053	7,254
Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	52,703	71,894
Unpaid Principal Balance	71,511	94,812
Related Allowance	0	0
Average Recorded Investment	48,772	96,762
Interest Income Recognized	721	797
Commercial and industrial
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	86,246	142,244
Unpaid Principal Balance	110,509	166,418
Related Allowance	6,013	10,838
Average Recorded Investment	102,294	147,769
Interest Income Recognized	773	3,121
Commercial and industrial | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	57,935	81,649
Unpaid Principal Balance	68,894	83,579
Related Allowance	6,013	10,838
Average Recorded Investment	70,339	58,494
Interest Income Recognized	1,121	2,629
Commercial and industrial | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	28,311	60,595
Unpaid Principal Balance	41,615	82,839
Related Allowance	0	0
Average Recorded Investment	31,955	89,275
Interest Income Recognized	348	492
Commercial real estate — owner occupied
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	7,518	26,234
Unpaid Principal Balance	8,575	26,766
Related Allowance	20	2,973
Average Recorded Investment	19,503	14,072
Interest Income Recognized	143	772
Commercial real estate — owner occupied | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	3,746	23,796
Unpaid Principal Balance	3,752	23,937
Related Allowance	20	2,973
Average Recorded Investment	15,460	12,124
Interest Income Recognized	143	736
Commercial real estate — owner occupied | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	3,772	2,438
Unpaid Principal Balance	4,823	2,829
Related Allowance	0	0
Average Recorded Investment	4,043	1,948
Interest Income Recognized	0	36
Commercial and business lending
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	93,764	168,478
Unpaid Principal Balance	119,084	193,184
Related Allowance	6,033	13,811
Average Recorded Investment	121,797	161,841
Interest Income Recognized	916	3,893
Commercial and business lending | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	61,681	105,445
Unpaid Principal Balance	72,646	107,516
Related Allowance	6,033	13,811
Average Recorded Investment	85,799	70,618
Interest Income Recognized	1,264	3,365
Commercial and business lending | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	32,083	63,033
Unpaid Principal Balance	46,438	85,668
Related Allowance	0	0
Average Recorded Investment	35,998	91,223
Interest Income Recognized	348	528
Commercial real estate — investor
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	11,986	19,118
Unpaid Principal Balance	16,378	19,157
Related Allowance	287	1,597
Average Recorded Investment	15,922	16,924
Interest Income Recognized	905	1,739
Commercial real estate — investor | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	2,069	17,823
Unpaid Principal Balance	2,148	17,862
Related Allowance	287	1,597
Average Recorded Investment	14,929	16,924
Interest Income Recognized	13	1,694
Commercial real estate — investor | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	9,917	1,295
Unpaid Principal Balance	14,230	1,295
Related Allowance	0	0
Average Recorded Investment	993	0
Interest Income Recognized	892	45
Real estate construction
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	440	467
Unpaid Principal Balance	516	578
Related Allowance	74	86
Average Recorded Investment	451	484
Interest Income Recognized	22	29
Real estate construction | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	440	467
Unpaid Principal Balance	516	578
Related Allowance	74	86
Average Recorded Investment	451	484
Interest Income Recognized	22	29
Real estate construction | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
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
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	12,426	19,585
Unpaid Principal Balance	16,894	19,735
Related Allowance	361	1,683
Average Recorded Investment	16,373	17,408
Interest Income Recognized	927	1,768
Commercial real estate lending | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	2,509	18,290
Unpaid Principal Balance	2,664	18,440
Related Allowance	361	1,683
Average Recorded Investment	15,380	17,408
Interest Income Recognized	35	1,723
Commercial real estate lending | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	9,917	1,295
Unpaid Principal Balance	14,230	1,295
Related Allowance	0	0
Average Recorded Investment	993	0
Interest Income Recognized	892	45
Total commercial
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	106,190	188,063
Unpaid Principal Balance	135,978	212,919
Related Allowance	6,394	15,494
Average Recorded Investment	138,170	179,249
Interest Income Recognized	1,843	5,661
Total commercial | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	64,190	123,735
Unpaid Principal Balance	75,310	125,956
Related Allowance	6,394	15,494
Average Recorded Investment	101,179	88,026
Interest Income Recognized	1,299	5,088
Total commercial | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	42,000	64,328
Unpaid Principal Balance	60,668	86,963
Related Allowance	0	0
Average Recorded Investment	36,991	91,223
Interest Income Recognized	544	573
Residential mortgage
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	50,722	47,486
Unpaid Principal Balance	54,244	50,126
Related Allowance	5,937	6,512
Average Recorded Investment	52,093	45,410
Interest Income Recognized	1,493	1,831
Residential mortgage | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	40,797	40,561
Unpaid Principal Balance	44,197	42,922
Related Allowance	5,937	6,512
Average Recorded Investment	41,589	40,411
Interest Income Recognized	1,321	1,614
Residential mortgage | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	9,925	6,925
Unpaid Principal Balance	10,047	7,204
Related Allowance	0	0
Average Recorded Investment	10,504	4,999
Interest Income Recognized	172	217
Home equity
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	10,470	10,891
Unpaid Principal Balance	11,485	11,631
Related Allowance	3,327	3,718
Average Recorded Investment	11,123	11,061
Interest Income Recognized	436	556
Home equity | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	9,692	10,250
Unpaid Principal Balance	10,689	10,986
Related Allowance	3,327	3,718
Average Recorded Investment	9,846	10,521
Interest Income Recognized	431	549
Home equity | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	778	641
Unpaid Principal Balance	796	645
Related Allowance	0	0
Average Recorded Investment	1,277	540
Interest Income Recognized	5	7
Other consumer
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	1,186	1,135
Unpaid Principal Balance	1,188	1,138
Related Allowance	123	122
Average Recorded Investment	1,188	1,140
Interest Income Recognized	2	3
Other consumer | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	1,186	1,135
Unpaid Principal Balance	1,188	1,138
Related Allowance	123	122
Average Recorded Investment	1,188	1,140
Interest Income Recognized	2	3
Other consumer | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
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
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	62,378	59,512
Unpaid Principal Balance	66,917	62,895
Related Allowance	9,387	10,352
Average Recorded Investment	64,404	57,611
Interest Income Recognized	1,931	2,390
Total consumer | Loans with a related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	51,675	51,946
Unpaid Principal Balance	56,074	55,046
Related Allowance	9,387	10,352
Average Recorded Investment	52,623	52,072
Interest Income Recognized	1,754	2,166
Total consumer | Loans with no related allowance
Loan and Lease Receivables, Impaired [Abstract]
Recorded Investment	10,703	7,566
Unpaid Principal Balance	10,843	7,849
Related Allowance	0	0
Average Recorded Investment	11,781	5,539
Interest Income Recognized	177	$ 224
Bank Mutual
Loan and Lease Receivables, Impaired [Abstract]
Purchased credit-impaired loans	$ 13,000