Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from Contracts with Customers
Net interest income	$ 131,481	$ 127,822	$ 260,639	$ 266,505
Not in scope of Topic 606	8,806	13,868	15,209	22,776
Total noninterest income	49,371	45,656	93,239	94,884
Total revenue	180,852	173,478	353,878	361,389
Retail Banking
Revenue from Contracts with Customers
Net interest income	97,106	91,675	191,560	181,558
Not in scope of Topic 606	1,868	3,403	5,222	7,042
Total noninterest income	22,495	22,172	46,070	48,548
Total revenue	119,601	113,847	237,630	230,106
Commercial Banking
Revenue from Contracts with Customers
Net interest income	40,234	37,565	78,500	71,979
Not in scope of Topic 606	2,282	5,893	3,604	8,921
Total noninterest income	19,528	18,055	35,569	35,851
Total revenue	59,762	55,620	114,069	107,830
Treasury and Other
Revenue from Contracts with Customers
Net interest income	(5,859)	(1,418)	(9,421)	12,968
Not in scope of Topic 606	4,656	4,572	6,383	6,813
Total noninterest income	7,348	5,429	11,600	10,485
Total revenue	1,489	4,011	2,179	23,453
Service charges on deposit accounts.
Revenue from Contracts with Customers
Revenue by type of service	6,632	5,927	13,350	14,877
Service charges on deposit accounts. | Retail Banking
Revenue from Contracts with Customers
Revenue by type of service	5,788	5,469	11,874	13,556
Service charges on deposit accounts. | Commercial Banking
Revenue from Contracts with Customers
Revenue by type of service	341	326	564	677
Service charges on deposit accounts. | Treasury and Other
Revenue from Contracts with Customers
Revenue by type of service	503	132	912	644
Credit and debit card fees
Revenue from Contracts with Customers
Revenue by type of service	16,132	10,397	30,085	24,883
Credit and debit card fees | Commercial Banking
Revenue from Contracts with Customers
Revenue by type of service	14,692	10,122	27,217	23,009
Credit and debit card fees | Treasury and Other
Revenue from Contracts with Customers
Revenue by type of service	1,440	275	2,868	1,874
Other service charges and fees.
Revenue from Contracts with Customers
Revenue by type of service	7,955	5,133	14,346	10,947
Other service charges and fees. | Retail Banking
Revenue from Contracts with Customers
Revenue by type of service	5,983	4,580	11,547	9,454
Other service charges and fees. | Commercial Banking
Revenue from Contracts with Customers
Revenue by type of service	1,590	215	2,065	639
Other service charges and fees. | Treasury and Other
Revenue from Contracts with Customers
Revenue by type of service	382	338	734	854
Trust and investment services income
Revenue from Contracts with Customers
Revenue by type of service	8,707	8,664	17,199	18,255
Trust and investment services income | Retail Banking
Revenue from Contracts with Customers
Revenue by type of service	8,707	8,664	17,199	18,255
Other
Revenue from Contracts with Customers
Revenue by type of service	1,139	1,667	3,050	3,146
Other | Retail Banking
Revenue from Contracts with Customers
Revenue by type of service	149	56	228	241
Other | Commercial Banking
Revenue from Contracts with Customers
Revenue by type of service	623	1,499	2,119	2,605
Other | Treasury and Other
Revenue from Contracts with Customers
Revenue by type of service	$ 367	$ 112	$ 703	$ 300