Loans and Allowance for Credit Losses - Schedule of Shows the Age Analysis of Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Total	$ 17,915,695	$ 17,778,354
Total Past Due
Financing Receivable, Past Due [Line Items]
Total	110,997	110,000
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	49,798	60,210
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	12,776	17,350
90 or More Days Past Due
Financing Receivable, Past Due [Line Items]
Total	48,423	32,440
Current
Financing Receivable, Past Due [Line Items]
Total	17,804,698	17,668,354
Commercial and industrial | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	3,412,693	3,266,575
Commercial and industrial | Total Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	6,074	118
Commercial and industrial | 30-59 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	5,984	28
Commercial and industrial | 60-89 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	0
Commercial and industrial | 90 or More Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	90	90
Commercial and industrial | Current | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	3,406,619	3,266,457
Commercial real estate | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	7,106,609	7,044,078
Commercial real estate | Total Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	34,778	32,693
Commercial real estate | 30-59 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	12,400	17,081
Commercial real estate | 60-89 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	0	6,432
Commercial real estate | 90 or More Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	22,378	9,180
Commercial real estate | Current | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	7,071,831	7,011,385
Commercial construction | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	459,120	491,649
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	459,120	491,649
Business banking | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,407,732	1,435,203
Business banking | Total Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	18,840	17,111
Business banking | 30-59 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	8,605	13,680
Business banking | 60-89 Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	3,506	1,605
Business banking | 90 or More Days Past Due | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	6,729	1,826
Business banking | Current | Commercial Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,388,892	1,418,092
Residential real estate | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	3,906,172	3,928,382
Residential real estate | Total Past Due | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	31,334	40,770
Residential real estate | 30-59 Days Past Due | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	13,074	21,037
Residential real estate | 60-89 Days Past Due | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	6,340	6,947
Residential real estate | 90 or More Days Past Due | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	11,920	12,786
Residential real estate | Current | Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total	3,874,838	3,887,612
Consumer home equity | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,405,244	1,385,288
Consumer home equity | Total Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	18,839	17,898
Consumer home equity | 30-59 Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	8,865	7,254
Consumer home equity | 60-89 Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	2,784	2,195
Consumer home equity | 90 or More Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	7,190	8,449
Consumer home equity | Current | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,386,405	1,367,390
Other Consumer | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	218,125	227,179
Other Consumer | Total Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	1,132	1,410
Other Consumer | 30-59 Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	870	1,130
Other Consumer | 60-89 Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	146	171
Other Consumer | 90 or More Days Past Due | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	116	109
Other Consumer | Current | Consumer Portfolio Segment
Financing Receivable, Past Due [Line Items]
Total	$ 216,993	$ 225,769