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	Jun. 30, 2023	Dec. 31, 2022
Financial assets:
Cash and cash equivalents	$ 6,377,887	$ 3,481,784
Interest-bearing deposits with banks	17,169	139,021
Resale agreements	635,000	792,192
HTM debt securities	2,975,933	3,001,868
Restricted equity securities, at cost	79,206	78,624
Financial liabilities:
Repurchase agreements	0	300,000
Carrying Amount
Financial assets:
Cash and cash equivalents	6,377,887	3,481,784
Interest-bearing deposits with banks	17,169	139,021
Resale agreements	635,000	792,192
HTM debt securities	2,975,933	3,001,868
Restricted equity securities, at cost	79,206	78,624
Loans held-for-sale	2,830	25,644
Loans held-for-investment, net	49,192,964	47,606,785
Mortgage servicing rights	5,537	6,235
Accrued interest receivable	288,526	263,430
Financial liabilities:
Demand, checking, savings and money market deposits	38,679,009	42,637,316
Time deposits	16,979,777	13,330,533
Repurchase agreements		300,000
Short-term borrowings	4,500,000
Long-term debt	148,097	147,950
Accrued interest payable	107,457	37,198
Estimated Fair Value
Financial assets:
Cash and cash equivalents	6,377,887	3,481,784
Interest-bearing deposits with banks	17,169	139,021
Resale agreements	541,441	693,656
HTM debt securities	2,440,484	2,455,171
Restricted equity securities, at cost	79,206	78,624
Loans held-for-sale	2,830	25,644
Loans held-for-investment, net	48,197,217	46,670,690
Mortgage servicing rights	10,078	10,917
Accrued interest receivable	288,526	263,430
Financial liabilities:
Demand, checking, savings and money market deposits	38,679,009	42,637,316
Time deposits	16,866,296	13,228,777
Repurchase agreements		304,097
Short-term borrowings	4,500,000
Long-term debt	141,990	143,483
Accrued interest payable	107,457	37,198
Estimated Fair Value | Level 1
Financial assets:
Cash and cash equivalents	6,377,887	3,481,784
Interest-bearing deposits with banks	0	0
Resale agreements	0	0
HTM debt securities	474,137	471,469
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
Repurchase agreements		0
Short-term 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	17,169	139,021
Resale agreements	541,441	693,656
HTM debt securities	1,966,347	1,983,702
Restricted equity securities, at cost	79,206	78,624
Loans held-for-sale	2,830	25,644
Loans held-for-investment, net	0	0
Mortgage servicing rights	0	0
Accrued interest receivable	288,526	263,430
Financial liabilities:
Demand, checking, savings and money market deposits	38,679,009	42,637,316
Time deposits	16,866,296	13,228,777
Repurchase agreements		304,097
Short-term borrowings	4,500,000
Long-term debt	141,990	143,483
Accrued interest payable	107,457	37,198
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	48,197,217	46,670,690
Mortgage servicing rights	10,078	10,917
Accrued interest receivable	0	0
Financial liabilities:
Demand, checking, savings and money market deposits	0	0
Time deposits	0	0
Repurchase agreements		0
Short-term borrowings	0
Long-term debt	0	0
Accrued interest payable	$ 0	$ 0