Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue from Contracts with Customers
Net interest income	$ 132,593	$ 134,002	$ 393,232	$ 400,507
Not in scope of Topic 606	9,728	11,307	24,937	34,082
Total noninterest income	50,104	48,898	143,343	143,782
Total revenue	182,697	182,900	536,575	544,289
Retail Banking
Revenue from Contracts with Customers
Net interest income	97,547	96,709	289,107	278,267
Not in scope of Topic 606	1,640	4,493	6,862	11,534
Total noninterest income	22,698	24,649	68,768	73,197
Total revenue	120,245	121,358	357,875	351,464
Commercial Banking
Revenue from Contracts with Customers
Net interest income	41,218	38,851	119,718	110,830
Not in scope of Topic 606	1,454	1,434	5,058	10,355
Total noninterest income	18,317	16,679	53,886	52,530
Total revenue	59,535	55,530	173,604	163,360
Treasury and Other
Revenue from Contracts with Customers
Net interest income	(6,172)	(1,558)	(15,593)	11,410
Not in scope of Topic 606	6,634	5,380	13,017	12,193
Total noninterest income	9,089	7,570	20,689	18,055
Total revenue	2,917	6,012	5,096	29,465
Service charges on deposit accounts.
Revenue from Contracts with Customers
Revenue by type of service	6,989	6,523	20,339	21,400
Service charges on deposit accounts. | Retail Banking
Revenue from Contracts with Customers
Revenue by type of service	6,151	5,734	18,025	19,290
Service charges on deposit accounts. | Commercial Banking
Revenue from Contracts with Customers
Revenue by type of service	335	332	899	1,009
Service charges on deposit accounts. | Treasury and Other
Revenue from Contracts with Customers
Revenue by type of service	503	457	1,415	1,101
Credit and debit card fees
Revenue from Contracts with Customers
Revenue by type of service	15,407	13,495	45,492	38,378
Credit and debit card fees | Commercial Banking
Revenue from Contracts with Customers
Revenue by type of service	14,105	12,259	41,322	35,268
Credit and debit card fees | Treasury and Other
Revenue from Contracts with Customers
Revenue by type of service	1,302	1,236	4,170	3,110
Other service charges and fees.
Revenue from Contracts with Customers
Revenue by type of service	7,671	6,324	22,017	17,271
Other service charges and fees. | Retail Banking
Revenue from Contracts with Customers
Revenue by type of service	6,218	5,433	17,765	14,887
Other service charges and fees. | Commercial Banking
Revenue from Contracts with Customers
Revenue by type of service	1,036	570	3,101	1,209
Other service charges and fees. | Treasury and Other
Revenue from Contracts with Customers
Revenue by type of service	417	321	1,151	1,175
Trust and investment services income
Revenue from Contracts with Customers
Revenue by type of service	8,625	8,664	25,824	26,919
Trust and investment services income | Retail Banking
Revenue from Contracts with Customers
Revenue by type of service	8,625	8,664	25,824	26,919
Other
Revenue from Contracts with Customers
Revenue by type of service	1,684	2,585	4,734	5,732
Other | Retail Banking
Revenue from Contracts with Customers
Revenue by type of service	64	325	292	567
Other | Commercial Banking
Revenue from Contracts with Customers
Revenue by type of service	1,387	2,084	3,506	4,689
Other | Treasury and Other
Revenue from Contracts with Customers
Revenue by type of service	$ 233	$ 176	$ 936	$ 476