Loans and Leases - Credit Risk Rating Categories for Loans and Leases Held for Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 21,920,946	$ 28,609,129	$ 27,660,041
Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	14,034,491	15,730,324	15,164,765
Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,737,537	4,152,172	3,759,500
Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	4,754,430	8,281,962	8,271,182
Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	394,488	444,671	$ 464,594
Classified
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	211,095	118,271
Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	201,035	107,905
Classified | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	0	0
Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	9,682	10,091
Classified | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	378	275
Special Mention
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	360,131	566,259
Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	220,123	224,886
Special Mention | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,640	136,489
Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	129,121	197,976
Special Mention | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	8,247	6,908
Pass
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	21,349,720	27,924,599
Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	13,613,333	15,397,533
Pass | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,734,897	4,015,683
Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	4,615,627	8,073,895
Pass | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	385,863	437,488
Asset-based | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,287,893	5,140,209
Asset-based | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,602	865
Asset-based | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	12,552	56,836
Asset-based | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,272,739	5,082,508
Venture Capital Loans | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,464,160	2,033,302
Venture Capital Loans | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,001	2,753
Venture Capital Loans | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	100,533	127,907
Venture Capital Loans | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,361,626	1,902,642
Other Commercial | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,002,377	1,108,451
Other Commercial | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,079	6,473
Other Commercial | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	16,036	13,233
Other Commercial | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	981,262	1,088,745
Commercial Real Estate Construction Loan Receivable | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	465,266	898,592
Commercial Real Estate Construction Loan Receivable | Classified | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	0	0
Commercial Real Estate Construction Loan Receivable | Special Mention | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	0	91,334
Commercial Real Estate Construction Loan Receivable | Pass | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	465,266	807,258
Residential Real Estate Construction Financing Receivable | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,272,271	3,253,580
Residential Real Estate Construction Financing Receivable | Classified | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	0	0
Residential Real Estate Construction Financing Receivable | Special Mention | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,640	45,155
Residential Real Estate Construction Financing Receivable | Pass | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,269,631	3,208,425
Commercial | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,526,308	3,846,831
Commercial | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	34,018	43,737
Commercial | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	127,716	106,493
Commercial | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,364,574	3,696,601
Multi-Family Real Estate Loans | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,279,659	5,607,865
Multi-Family Real Estate Loans | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	70,809	3,611
Multi-Family Real Estate Loans | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	45,646	60,330
Multi-Family Real Estate Loans | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,163,204	5,543,924
Other Residential Real Estate | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,228,524	6,275,628
Other Residential Real Estate | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	96,208	60,557
Other Residential Real Estate | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	46,761	58,063
Other Residential Real Estate | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 5,085,555	6,157,008
Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		$ 28,609,129