Assets and Liabilities Measured at Fair Value - Carrying Amount and Fair Values for Other Financial Instruments that are not Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Assets:
HTM debt securities	$ 1,937,053	$ 1,944,126
Carrying Amount
Assets:
HTM debt securities	2,274,099	2,368,107
Loans and leases, net	18,959,003	17,968,982
Liabilities:
Deposits	24,020,618	23,460,975
Long-term debt	155,251	254,152
Fair Value
Assets:
HTM debt securities	1,937,053	1,944,126
Loans and leases, net	18,399,997	17,325,630
Liabilities:
Deposits	24,014,897	23,453,487
Long-term debt	152,675	248,657
Fair Value \| Level 1
Assets:
HTM debt securities	18,880	18,162
Loans and leases, net	0	0
Liabilities:
Deposits	0	0
Long-term debt	0	0
Fair Value \| Level 2
Assets:
HTM debt securities	1,918,173	1,925,964
Loans and leases, net	0	0
Liabilities:
Deposits	24,014,897	23,453,487
Long-term debt	0	0
Fair Value \| Level 3
Assets:
HTM debt securities	0	0
Loans and leases, net	18,399,997	17,325,630
Liabilities:
Deposits	0	0
Long-term debt	$ 152,675	$ 248,657

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