Loans and Allowance for Credit Losses for Loans - Summary of Allocation of Allowance for Loan Losses and Related Loans by Loan Portfolio Segment Disaggregated Based on Allowance Measurement Methodology (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for credit losses	$ 61,099		$ 75,855
Collectively evaluated for credit losses	523,901		482,995
Total	585,000	$ 579,500	558,850	$ 548,327	$ 519,310	$ 446,080
Individually evaluated for credit losses	411,599		329,702
Collectively evaluated for credit losses	48,861,224		48,470,009
Total	49,272,823		48,799,711
Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for credit losses	43,057		59,603
Collectively evaluated for credit losses	118,791		113,399
Total	161,848	173,415	173,002	166,365	149,243	133,359
Individually evaluated for credit losses	109,903		131,898
Collectively evaluated for credit losses	10,647,954		9,799,502
Total	10,757,857		9,931,400
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for credit losses	18,019		16,225
Collectively evaluated for credit losses	331,574		287,923
Total	349,593	334,979	304,148	309,028	301,093	249,598
Individually evaluated for credit losses	268,855		172,666
Collectively evaluated for credit losses	28,414,519		29,472,292
Total	28,683,374		29,644,958
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for credit losses	23		27
Collectively evaluated for credit losses	51,071		58,868
Total	51,094	48,830	58,895	51,545	47,697	42,957
Individually evaluated for credit losses	29,896		23,797
Collectively evaluated for credit losses	5,765,499		5,608,719
Total	5,795,395		5,632,516
Consumer loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for credit losses	0		0
Collectively evaluated for credit losses	22,465		22,805
Total	22,465	$ 22,276	22,805	$ 21,389	$ 21,277	$ 20,166
Individually evaluated for credit losses	2,945		1,341
Collectively evaluated for credit losses	4,033,252		3,589,496
Total	$ 4,036,197		$ 3,590,837