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, 2022	Dec. 31, 2021
Financial assets:
Cash and cash equivalents	$ 1,902,053	$ 3,912,935
Interest-bearing deposits with banks	712,709	736,492
Resale agreements	1,422,794	2,353,503
HTM debt securities	3,028,302	0
Restricted equity securities, at cost	77,962	77,434
Loans held-for-investment, net	45,938,806	41,152,202
Financial liabilities:
FHLB advances	174,776	249,331
Repurchase agreements	611,785	300,000
Carrying Amount
Financial assets:
Cash and cash equivalents	1,902,053	3,912,935
Interest-bearing deposits with banks	712,709	736,492
Resale agreements	1,422,794	2,353,503
HTM debt securities	3,028,302
Restricted equity securities, at cost	77,962	77,434
Loans held-for-sale	28,464	635
Loans held-for-investment, net	45,938,806	41,152,202
Mortgage servicing rights	5,909	5,706
Accrued interest receivable	172,008	159,833
Financial liabilities:
Demand, checking, savings and money market deposits	44,965,778	45,388,550
Time deposits	9,377,576	7,961,982
FHLB advances	174,776	249,331
Repurchase agreements	611,785	300,000
Long-term debt	147,801	147,658
Accrued interest payable	9,596	11,435
Estimated Fair Value
Financial assets:
Cash and cash equivalents	1,902,053	3,912,935
Interest-bearing deposits with banks	712,709	736,492
Resale agreements	1,348,036	2,335,901
HTM debt securities	2,656,549
Restricted equity securities, at cost	77,962	77,434
Loans held-for-sale	28,464	635
Loans held-for-investment, net	45,860,749	41,199,599
Mortgage servicing rights	10,349	9,104
Accrued interest receivable	172,008	159,833
Financial liabilities:
Demand, checking, savings and money market deposits	44,965,778	45,388,550
Time deposits	9,318,992	7,966,116
FHLB advances	175,207	250,372
Repurchase agreements	619,280	310,525
Long-term debt	139,206	151,020
Accrued interest payable	9,596	11,435
Estimated Fair Value | Level 1
Financial assets:
Cash and cash equivalents	1,902,053	3,912,935
Interest-bearing deposits with banks	0	0
Resale agreements	0	0
HTM debt securities	486,521
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	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	712,709	736,492
Resale agreements	1,348,036	2,335,901
HTM debt securities	2,170,028
Restricted equity securities, at cost	77,962	77,434
Loans held-for-sale	28,464	635
Loans held-for-investment, net	0	0
Mortgage servicing rights	0	0
Accrued interest receivable	172,008	159,833
Financial liabilities:
Demand, checking, savings and money market deposits	44,965,778	45,388,550
Time deposits	9,318,992	7,966,116
FHLB advances	175,207	250,372
Repurchase agreements	619,280	310,525
Long-term debt	139,206	151,020
Accrued interest payable	9,596	11,435
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
Restricted equity securities, at cost	0	0
Loans held-for-sale	0	0
Loans held-for-investment, net	45,860,749	41,199,599
Mortgage servicing rights	10,349	9,104
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	0
Long-term debt	0	0
Accrued interest payable	$ 0	$ 0