Loans and Leases - Nonaccrual and Performing Loans and Leases Held for Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Financing Receivable, Impaired [Line Items]
Nonaccrual	$ 87,124	$ 103,778	$ 66,538
Loans held for investment, net	25,672,381	28,609,129	24,352,072
Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	83,056	98,402	50,163
Loans held for investment, net	15,407,611	15,730,324	12,509,064
Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0	5,586
Loans held for investment, net	4,608,440	4,152,172	3,223,716
Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	3,543	5,210	10,402
Loans held for investment, net	5,229,107	8,281,962	8,114,695
Consumer
Financing Receivable, Impaired [Line Items]
Nonaccrual	525	166	387
Loans held for investment, net	427,223	444,671	$ 504,597
Performing
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	25,585,257	28,505,351
Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	15,324,555	15,631,922
Performing | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	4,608,440	4,152,172
Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	5,225,564	8,276,752
Performing | Consumer
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	426,698	444,505
Asset-based | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	420	865
Loans held for investment, net	2,068,327	5,140,209
Asset-based | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	2,067,907	5,139,344
Venture Capital Loans | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0
Loans held for investment, net	2,058,237	2,033,302
Venture Capital Loans | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	2,058,237	2,033,302
Other Commercial | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	3,123	4,345
Loans held for investment, net	1,102,543	1,108,451
Other Commercial | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	1,099,420	1,104,106
Commercial Real Estate Construction Loan Receivable | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0
Loans held for investment, net	910,327	898,592
Commercial Real Estate Construction Loan Receivable | Performing | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	910,327	898,592
Residential Real Estate Construction Financing Receivable | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0
Loans held for investment, net	3,698,113	3,253,580
Residential Real Estate Construction Financing Receivable | Performing | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	3,698,113	3,253,580
Commercial | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	32,996	42,509
Loans held for investment, net	3,808,751	3,846,831
Commercial | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	3,775,755	3,804,322
Multi-Family Real Estate Loans | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0
Loans held for investment, net	5,523,320	5,607,865
Multi-Family Real Estate Loans | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	5,523,320	5,607,865
Other Residential Real Estate | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	50,060	55,893
Loans held for investment, net	6,075,540	6,275,628
Other Residential Real Estate | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	$ 6,025,480	$ 6,219,735