Loans and Leases - Nonaccrual and Performing Loans and Leases Held for Investment (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Financing Receivable, Impaired [Line Items]
Nonaccrual	$ 104,886	$ 103,778	$ 78,527
Loans held for investment, net	22,258,210	28,609,129	26,501,137
Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	100,817	98,402	62,996
Loans held for investment, net	14,288,042	15,730,324	14,054,085
Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0	6,344
Loans held for investment, net	2,465,523	4,152,172	3,486,600
Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	3,864	5,210	8,964
Loans held for investment, net	5,094,786	8,281,962	8,476,806
Consumer
Financing Receivable, Impaired [Line Items]
Nonaccrual	205	166	223
Loans held for investment, net	409,859	444,671	$ 483,646
Performing
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	22,153,324	28,505,351
Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	14,187,225	15,631,922
Performing | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	2,465,523	4,152,172
Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	5,090,922	8,276,752
Performing | Consumer
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	409,654	444,505
Asset-based | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	385	865
Loans held for investment, net	2,357,098	5,140,209
Asset-based | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	2,356,713	5,139,344
Venture Capital Loans | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0
Loans held for investment, net	1,723,476	2,033,302
Venture Capital Loans | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	1,723,476	2,033,302
Other Commercial | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	3,479	4,345
Loans held for investment, net	1,014,212	1,108,451
Other Commercial | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	1,010,733	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	415,997	898,592
Commercial Real Estate Construction Loan Receivable | Performing | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	415,997	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	2,049,526	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	2,049,526	3,253,580
Commercial | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	37,191	42,509
Loans held for investment, net	3,610,320	3,846,831
Commercial | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	3,573,129	3,804,322
Multi-Family Real Estate Loans | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0
Loans held for investment, net	5,304,544	5,607,865
Multi-Family Real Estate Loans | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	5,304,544	5,607,865
Other Residential Real Estate | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	63,626	55,893
Loans held for investment, net	5,373,178	6,275,628
Other Residential Real Estate | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	$ 5,309,552	$ 6,219,735