Fair Value Measurement and Fair Value of Financial Instruments - Schedule of the Carrying and Fair Value Estimates Per the Fair Value Hierarchy of Financial Instruments Measured on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Financial assets:
Cash and cash equivalents	$ 4,438,870	$ 4,188,139
Interest-bearing deposits with banks	10,498	16,189
Resale agreements	425,000	425,000
HTM debt securities	2,858,978	2,870,058
Restricted equity securities, at cost	153,697	153,484
Loans held-for-investment, net	57,264,875	56,068,399
Financial liabilities:
FHLB advances	3,000,000	3,000,000
Repurchase agreements	494,027	0
Carrying Amount
Financial assets:
Cash and cash equivalents	4,438,870	4,188,139
Interest-bearing deposits with banks	10,498	16,189
Resale agreements	425,000	425,000
HTM debt securities	2,858,978	2,870,058
Restricted equity securities, at cost	153,697	153,484
Loans held-for-sale	27,585	20,976
Loans held-for-investment, net	57,264,875	56,068,399
Mortgage servicing rights	3,978	4,119
Accrued interest receivable	316,124	315,669
Financial liabilities:
Demand, checking, savings and money market deposits	43,508,071	41,797,887
Time deposits	25,411,484	25,284,814
FHLB advances	3,000,000	3,000,000
Repurchase agreements	494,027
Long-term debt	32,400	32,320
Accrued interest payable	54,474	60,513
Estimated Fair Value
Financial assets:
Cash and cash equivalents	4,438,870	4,188,139
Interest-bearing deposits with banks	10,498	16,189
Resale agreements	351,104	351,065
HTM debt securities	2,453,003	2,479,746
Restricted equity securities, at cost	153,697	153,484
Loans held-for-sale	27,585	20,976
Loans held-for-investment, net	55,875,553	54,665,865
Mortgage servicing rights	6,981	7,114
Accrued interest receivable	316,124	315,669
Financial liabilities:
Demand, checking, savings and money market deposits	43,508,071	41,797,887
Time deposits	25,384,802	25,285,076
FHLB advances	2,995,604	3,001,878
Repurchase agreements	494,004
Long-term debt	30,690	32,070
Accrued interest payable	54,009	60,513
Estimated Fair Value | Level 1
Financial assets:
Cash and cash equivalents	4,438,870	4,188,139
Interest-bearing deposits with banks	0	0
Resale agreements	0	0
HTM debt securities	526,048	524,887
Restricted equity securities, at cost	0	0
Loans held-for-sale	0	0
Loans held-for-investment, net	0	0
Mortgage servicing rights	0	0
Accrued interest receivable	0	0
Financial liabilities:
Demand, checking, savings and money market deposits	0	0
Time deposits	0	0
FHLB advances	0	0
Repurchase agreements	0
Long-term debt	0	0
Accrued interest payable	0	0
Estimated Fair Value | Level 2
Financial assets:
Cash and cash equivalents	0	0
Interest-bearing deposits with banks	10,498	16,189
Resale agreements	351,104	351,065
HTM debt securities	1,926,955	1,954,859
Restricted equity securities, at cost	153,697	153,484
Loans held-for-sale	27,585	20,976
Loans held-for-investment, net	0	0
Mortgage servicing rights	0	0
Accrued interest receivable	316,124	315,669
Financial liabilities:
Demand, checking, savings and money market deposits	43,508,071	41,797,887
Time deposits	25,384,802	25,285,076
FHLB advances	2,995,604	3,001,878
Repurchase agreements	494,004
Long-term debt	30,690	32,070
Accrued interest payable	54,009	60,513
Estimated Fair Value | Level 3
Financial assets:
Cash and cash equivalents	0	0
Interest-bearing deposits with banks	0	0
Resale agreements	0	0
HTM debt securities	0	0
Restricted equity securities, at cost	0	0
Loans held-for-sale	0	0
Loans held-for-investment, net	55,875,553	54,665,865
Mortgage servicing rights	6,981	7,114
Accrued interest receivable	0	0
Financial liabilities:
Demand, checking, savings and money market deposits	0	0
Time deposits	0	0
FHLB advances	0	0
Repurchase agreements	0
Long-term debt	0	0
Accrued interest payable	$ 0	$ 0