Loans and Allowance for Credit Losses - Summary of Shows the Age Analysis of Past Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Total	$ 13,899,968	$ 13,562,528
Total Past Due
Financing Receivable, Past Due [Line Items]
Total	53,003	67,967
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	30,256	42,715
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	7,511	6,360
90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total	15,236	18,892
Current
Financing Receivable, Past Due [Line Items]
Total	13,846,965	13,494,561
Commercial and industrial | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	3,072,350	3,132,528
Commercial and industrial | Total Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,495	3,759
Commercial and industrial | 30-59 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,030	1,300
Commercial and industrial | 60-89 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	385
Commercial and industrial | 90 or More Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	465	2,074
Commercial and industrial | Current | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	3,070,855	3,128,769
Commercial real estate | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	5,393,227	5,151,363
Commercial real estate | Total Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial real estate | 30-59 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial real estate | 60-89 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial real estate | 90 or More Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial real estate | Current | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	5,393,227	5,151,363
Commercial construction | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	380,637	334,259
Commercial construction | Total Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial construction | 30-59 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial construction | 60-89 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial construction | 90 or More Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial construction | Current | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	380,637	334,259
Business banking | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,091,816	1,095,238
Business banking | Total Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	7,921	11,004
Business banking | 30-59 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	4,536	6,642
Business banking | 60-89 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,846	845
Business banking | 90 or More Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,539	3,517
Business banking | Current | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,083,895	1,084,234
Residential real estate | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	2,568,781	2,480,055
Residential real estate | Total Past Due | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	26,455	36,185
Residential real estate | 30-59 Days Past Due | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	17,988	25,877
Residential real estate | 60-89 Days Past Due | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	2,846	3,852
Residential real estate | 90 or More Days Past Due | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	5,621	6,456
Residential real estate | Current | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	2,542,326	2,443,870
Consumer home equity | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,197,007	1,191,307
Consumer home equity | Total Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	16,323	15,895
Consumer home equity | 30-59 Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	6,232	8,262
Consumer home equity | 60-89 Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	2,661	1,108
Consumer home equity | 90 or More Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	7,430	6,525
Consumer home equity | Current | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,180,684	1,175,412
Other Consumer | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	196,150	177,778
Other Consumer | Total Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	809	1,124
Other Consumer | 30-59 Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	470	634
Other Consumer | 60-89 Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	158	170
Other Consumer | 90 or More Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	181	320
Other Consumer | Current | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	$ 195,341	$ 176,654