Fair Value of Assets and Liabilities - Carrying Amount and Estimated Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Carrying Amount
Financial assets
Cash and cash equivalents	$ 981,485	$ 848,408
Debt securities, held-to-maturity	3,261,575	3,294,847
Loans receivable, net of ACL	17,008,118	17,055,808
Total financial assets	21,251,178	21,199,063
Financial liabilities
Term deposits	3,140,333	3,139,821
FHLB advances	1,520,000	1,800,000
Repurchase agreements and other borrowed funds	1,931,513	1,860,816
Subordinated debentures	133,145	133,105
Total financial liabilities	6,724,991	6,933,742
Estimated Fair Value | Level 1
Financial assets
Cash and cash equivalents	981,485	848,408
Debt securities, held-to-maturity	0	0
Loans receivable, net of ACL	0	0
Total financial assets	981,485	848,408
Financial liabilities
Term deposits	0	0
FHLB advances	0	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	2,953,423	2,968,570
Loans receivable, net of ACL	0	0
Total financial assets	2,953,423	2,968,570
Financial liabilities
Term deposits	3,172,931	3,176,722
FHLB advances	1,520,969	1,797,310
Repurchase agreements and other borrowed funds	1,931,513	1,860,816
Subordinated debentures	122,646	122,785
Total financial liabilities	6,748,059	6,957,633
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	17,030,076	17,017,298
Total financial assets	17,030,076	17,017,298
Financial liabilities
Term deposits	0	0
FHLB advances	0	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Total financial liabilities	$ 0	$ 0