Loans and Leases - Credit Risk Rating Categories for Loans and Leases Held for Investment (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 22,258,210	$ 28,609,129	$ 26,501,137
Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	14,288,042	15,730,324	14,054,085
Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,465,523	4,152,172	3,486,600
Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,094,786	8,281,962	8,476,806
Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	409,859	444,671	$ 483,646
Classified
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	211,934	118,271
Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	199,707	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	11,780	10,091
Classified | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	447	275
Special Mention
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	366,368	566,259
Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	207,869	224,886
Special Mention | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,376	136,489
Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	148,267	197,976
Special Mention | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	7,856	6,908
Pass
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	21,679,908	27,924,599
Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	13,880,466	15,397,533
Pass | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,463,147	4,015,683
Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	4,934,739	8,073,895
Pass | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	401,556	437,488
Asset-based | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,357,098	5,140,209
Asset-based | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,650	865
Asset-based | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	13,368	56,836
Asset-based | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,340,080	5,082,508
Venture Capital Loans | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,723,476	2,033,302
Venture Capital Loans | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,614	2,753
Venture Capital Loans | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	122,482	127,907
Venture Capital Loans | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,598,380	1,902,642
Other Commercial | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,014,212	1,108,451
Other Commercial | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,516	6,473
Other Commercial | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	12,417	13,233
Other Commercial | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	996,279	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	415,997	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	415,997	807,258
Residential Real Estate Construction Financing Receivable | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,049,526	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	2,376	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	2,047,150	3,208,425
Commercial | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,610,320	3,846,831
Commercial | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	39,768	43,737
Commercial | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	121,084	106,493
Commercial | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,449,468	3,696,601
Multi-Family Real Estate Loans | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,304,544	5,607,865
Multi-Family Real Estate Loans | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	87,390	3,611
Multi-Family Real Estate Loans | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	30,743	60,330
Multi-Family Real Estate Loans | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,186,411	5,543,924
Other Residential Real Estate | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,373,178	6,275,628
Other Residential Real Estate | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	72,549	60,557
Other Residential Real Estate | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	56,042	58,063
Other Residential Real Estate | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 5,244,587	6,157,008
Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		$ 28,609,129