Fair Value Measurement and Fair Value of Financial Instruments - Carrying and Fair Value Estimates per the Fair Value Hierarchy of Financial Instruments Measured on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financial assets:
Cash and cash equivalents	$ 4,210,801	$ 4,614,984
Interest-bearing deposits with banks	24,593	10,498
Securities purchased under resale agreements (“resale agreements”)	485,000	785,000
HTM debt securities	2,948,642	2,956,040
Restricted equity securities, at cost	164,402	79,811
Financial liabilities:
Federal Home Loan Bank (“FHLB”) advances	3,500,000	0
Carrying Amount
Financial assets:
Cash and cash equivalents	4,210,801	4,614,984
Interest-bearing deposits with banks	24,593	10,498
Securities purchased under resale agreements (“resale agreements”)	485,000	785,000
HTM debt securities	2,948,642	2,956,040
Restricted equity securities, at cost	164,402	79,811
Loans held-for-sale	13,280	116
Loans held-for-investment, net	51,322,224	51,542,039
Mortgage servicing rights	6,234	6,602
Accrued interest receivable	336,428	331,490
Financial liabilities:
Demand, checking, savings and money market deposits	37,789,344	38,048,974
Time deposits	20,771,280	18,043,464
Short-term borrowings	19,173
Federal Home Loan Bank (“FHLB”) advances	3,500,000
BTFP borrowings		4,500,000
Long-term debt	31,768	148,249
Accrued interest payable	63,470	205,430
Estimated Fair Value
Financial assets:
Cash and cash equivalents	4,210,801	4,614,984
Interest-bearing deposits with banks	24,593	10,498
Securities purchased under resale agreements (“resale agreements”)	391,403	699,056
HTM debt securities	2,414,478	2,453,971
Restricted equity securities, at cost	164,402	79,811
Loans held-for-sale	13,280	116
Loans held-for-investment, net	49,849,727	50,256,565
Mortgage servicing rights	10,787	9,470
Accrued interest receivable	336,428	331,490
Financial liabilities:
Demand, checking, savings and money market deposits	37,789,344	38,048,974
Time deposits	20,715,628	18,004,951
Short-term borrowings	19,173
Federal Home Loan Bank (“FHLB”) advances	3,500,000
BTFP borrowings		4,500,000
Long-term debt	30,201	150,896
Accrued interest payable	63,470	205,430
Estimated Fair Value | Level 1
Financial assets:
Cash and cash equivalents	4,210,801	4,614,984
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements (“resale agreements”)	0	0
HTM debt securities	485,400	488,551
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
Short-term borrowings	0
Federal Home Loan Bank (“FHLB”) advances	0
BTFP borrowings		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	24,593	10,498
Securities purchased under resale agreements (“resale agreements”)	391,403	699,056
HTM debt securities	1,929,078	1,965,420
Restricted equity securities, at cost	164,402	79,811
Loans held-for-sale	13,280	116
Loans held-for-investment, net	0	0
Mortgage servicing rights	0	0
Accrued interest receivable	336,428	331,490
Financial liabilities:
Demand, checking, savings and money market deposits	37,789,344	38,048,974
Time deposits	20,715,628	18,004,951
Short-term borrowings	19,173
Federal Home Loan Bank (“FHLB”) advances	3,500,000
BTFP borrowings		4,500,000
Long-term debt	30,201	150,896
Accrued interest payable	63,470	205,430
Estimated Fair Value | Level 3
Financial assets:
Cash and cash equivalents	0	0
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements (“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	49,849,727	50,256,565
Mortgage servicing rights	10,787	9,470
Accrued interest receivable	0	0
Financial liabilities:
Demand, checking, savings and money market deposits	0	0
Time deposits	0	0
Short-term borrowings	0
Federal Home Loan Bank (“FHLB”) advances	0
BTFP borrowings		0
Long-term debt	0	0
Accrued interest payable	$ 0	$ 0