Loans and Leases - Credit Risk Rating Categories for Loans and Leases Held for Investment (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 26,501,137	$ 22,941,548	$ 19,506,257
Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	13,549,646	11,178,720	8,413,020
Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,991,039	3,437,127	3,505,584
Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	8,476,806	7,868,051	7,222,244
Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	483,646	457,650	$ 365,409
Classified
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	104,264	116,104
Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	78,646	79,906
Classified | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	13,287	4,715
Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	12,032	31,044
Classified | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	299	439
Special Mention
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	480,261	391,611
Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	176,724	211,657
Special Mention | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	195,102	69,447
Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	103,043	108,666
Special Mention | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,392	1,841
Pass
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	25,916,612	22,433,833
Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	13,294,276	10,887,157
Pass | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,782,650	3,362,965
Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	8,361,731	7,728,341
Pass | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	477,955	455,370
Asset-based | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,068,112	4,075,477
Asset-based | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,189	4,591
Asset-based | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	54,131	78,305
Asset-based | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,012,792	3,992,581
Venture Capital Loans | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,179,190	2,320,593
Venture Capital Loans | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,116	4,794
Venture Capital Loans | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	37,831	14,833
Venture Capital Loans | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,138,243	2,300,966
Other Commercial | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,229,504	1,471,981
Other Commercial | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	7,727	21,659
Other Commercial | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	11,081	15,528
Other Commercial | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,210,696	1,434,794
Commercial Real Estate Construction Loan Receivable | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	837,423	832,591
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	155,745	67,727
Commercial Real Estate Construction Loan Receivable | Pass | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	681,678	764,864
Residential Real Estate Construction Financing Receivable | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,153,616	2,604,536
Residential Real Estate Construction Financing Receivable | Classified | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	13,287	4,715
Residential Real Estate Construction Financing Receivable | Special Mention | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	39,357	1,720
Residential Real Estate Construction Financing Receivable | Pass | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,100,972	2,598,101
Commercial | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,670,515	3,762,299
Commercial | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	46,203	62,206
Commercial | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	157,476	191,809
Commercial | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,466,836	3,508,284
Residential Real Estate [Member] | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	9,879,131	7,416,421
Residential Real Estate [Member] | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	32,443	17,700
Residential Real Estate [Member] | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	19,248	19,848
Residential Real Estate [Member] | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 9,827,440	7,378,873
Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		$ 22,941,548