Allowance for Credit Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	$ 33,719	$ 22,124
Collectively evaluated	5,979,260	5,110,068
Acquired with deteriorated credit quality	8,253	8,748
Total	6,021,232	5,137,823
Total		5,140,940
Individually evaluated	1,355	352
Collectively evaluated	69,769	39,651
Less: Allowance for credit losses	71,124	40,003	$ 37,688
Non-owner occupied commercial
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	12,112
Collectively evaluated	2,382,717
Acquired with deteriorated credit quality	4,117
Total	2,398,946
Individually evaluated	355
Collectively evaluated	25,555
Less: Allowance for credit losses	25,910	0
Owner occupied commercial
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	16,547
Collectively evaluated	809,935
Acquired with deteriorated credit quality	610
Total	827,092
Individually evaluated	96
Collectively evaluated	3,859
Less: Allowance for credit losses	3,955	0
Mortgage-backed securities, multifamily
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	0
Collectively evaluated	813,225
Acquired with deteriorated credit quality	0
Total	813,225
Individually evaluated	0
Collectively evaluated	7,253
Less: Allowance for credit losses	7,253
Non-owner occupied residential
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	1,459
Collectively evaluated	198,334
Acquired with deteriorated credit quality	436
Total	200,229
Individually evaluated	43
Collectively evaluated	3,278
Less: Allowance for credit losses	3,321	0
Commercial, secured by real estate
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated		15,948
Collectively evaluated		3,567,540
Acquired with deteriorated credit quality		6,105
Total	4,239,492
Total		3,589,593
Individually evaluated		228	307
Collectively evaluated		28,722
Less: Allowance for credit losses	0	28,950	27,881
Commercial, industrial and other
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	1,596	1,504
Collectively evaluated	715,129	429,486
Acquired with deteriorated credit quality	1,464	944
Total	718,189
Total		431,934
Individually evaluated	830	5	7
Collectively evaluated	12,835	3,284
Less: Allowance for credit losses	13,665	3,289	1,742
Construction
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	515	1,663
Collectively evaluated	265,649	332,722
Acquired with deteriorated credit quality	719	784
Total	266,883
Total		335,169
Individually evaluated	0	0	0
Collectively evaluated	786	2,672
Less: Allowance for credit losses	786	2,672	3,015
Equipment finance
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	0	23
Collectively evaluated	116,690	111,053
Acquired with deteriorated credit quality	0	0
Total	116,690
Total		111,076
Individually evaluated	0	10	14
Collectively evaluated	6,552	947
Less: Allowance for credit losses	6,552	957	987
Residential mortgage
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	1,490	2,315
Collectively evaluated	375,482	332,486
Acquired with deteriorated credit quality	408	390
Total	377,380
Total		335,191
Individually evaluated	0	104	4
Collectively evaluated	3,623	1,621
Less: Allowance for credit losses	3,623	1,725	1,566
Consumer
Debt Securities, Allowance for Credit Loss [Line Items]
Individually evaluated	0	671
Collectively evaluated	302,099	336,781
Acquired with deteriorated credit quality	499	525
Total	302,598
Total		337,977
Individually evaluated	31	5	6
Collectively evaluated	6,028	2,405
Less: Allowance for credit losses	$ 6,059	$ 2,410	$ 2,497