Loans and Leases - Nonaccrual and Performing Loans and Leases Held for Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Financing Receivable, Impaired [Line Items]
Nonaccrual	$ 125,396	$ 103,778	$ 89,742
Loans held for investment, net	21,920,946	28,609,129	27,660,041
Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	119,794	98,402	75,823
Loans held for investment, net	14,034,491	15,730,324	15,164,765
Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0	0
Loans held for investment, net	2,737,537	4,152,172	3,759,500
Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	5,395	5,210	13,552
Loans held for investment, net	4,754,430	8,281,962	8,271,182
Consumer
Financing Receivable, Impaired [Line Items]
Nonaccrual	207	166	367
Loans held for investment, net	394,488	444,671	$ 464,594
Performing
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	21,795,550	28,505,351
Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	13,914,697	15,631,922
Performing | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	2,737,537	4,152,172
Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	4,749,035	8,276,752
Performing | Consumer
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	394,281	444,505
Asset-based | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	363	865
Loans held for investment, net	2,287,893	5,140,209
Asset-based | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	2,287,530	5,139,344
Venture Capital Loans | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	2,001	0
Loans held for investment, net	1,464,160	2,033,302
Venture Capital Loans | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	1,462,159	2,033,302
Other Commercial | Commercial
Financing Receivable, Impaired [Line Items]
Nonaccrual	3,031	4,345
Loans held for investment, net	1,002,377	1,108,451
Other Commercial | Performing | Commercial
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	999,346	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	465,266	898,592
Commercial Real Estate Construction Loan Receivable | Performing | Real Estate Construction and Land
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	465,266	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	2,272,271	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	2,272,271	3,253,580
Commercial | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	31,465	42,509
Loans held for investment, net	3,526,308	3,846,831
Commercial | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	3,494,843	3,804,322
Multi-Family Real Estate Loans | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	0	0
Loans held for investment, net	5,279,659	5,607,865
Multi-Family Real Estate Loans | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	5,279,659	5,607,865
Other Residential Real Estate | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Nonaccrual	88,329	55,893
Loans held for investment, net	5,228,524	6,275,628
Other Residential Real Estate | Performing | Real Estate Mortgage
Financing Receivable, Impaired [Line Items]
Loans held for investment, net	$ 5,140,195	$ 6,219,735