Fair Value of Assets and Liabilities - Carrying Amount and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Financial assets
Debt securities, held-to-maturity	$ 2,968,570	$ 3,180,194
Carrying Amount
Financial assets
Cash and cash equivalents	848,408	1,354,342
Debt securities, held-to-maturity	3,294,847	3,502,411
Loans receivable, net of ACL	17,055,808	16,005,325
Total financial assets	21,199,063	20,862,078
Financial liabilities
Term deposits	3,139,821	2,915,393
FHLB advances	1,800,000
FRB Bank Term Funding		2,740,000
Repurchase agreements and other borrowed funds	1,860,816	1,568,545
Subordinated debentures	133,105	132,943
Total financial liabilities	6,933,742	7,356,881
Estimated Fair Value | Level 1
Financial assets
Cash and cash equivalents	848,408	1,354,342
Debt securities, held-to-maturity	0	0
Loans receivable, net of ACL	0	0
Total financial assets	848,408	1,354,342
Financial liabilities
Term deposits	0	0
FHLB advances	0
FRB Bank Term Funding		0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Total financial liabilities	0	0
Estimated Fair Value | Level 2
Financial assets
Cash and cash equivalents	0	0
Debt securities, held-to-maturity	2,968,570	3,180,194
Loans receivable, net of ACL	0	0
Total financial assets	2,968,570	3,180,194
Financial liabilities
Term deposits	3,176,722	2,955,521
FHLB advances	1,797,310
FRB Bank Term Funding		2,738,031
Repurchase agreements and other borrowed funds	1,860,816	1,568,545
Subordinated debentures	122,785	119,768
Total financial liabilities	6,957,633	7,381,865
Estimated Fair Value | Level 3
Financial assets
Cash and cash equivalents	0	0
Debt securities, held-to-maturity	0	0
Loans receivable, net of ACL	17,017,298	16,133,681
Total financial assets	17,017,298	16,133,681
Financial liabilities
Term deposits	0	0
FHLB advances	0
FRB Bank Term Funding		0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Total financial liabilities	$ 0	$ 0