Loans and Leases - Credit Risk Rating Categories for Loans and Leases Held for Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 27,660,041	$ 22,941,548	$ 20,511,020
Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	14,630,749	11,178,720	9,580,957
Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	4,293,516	3,437,127	3,651,873
Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	8,271,182	7,868,051	6,872,222
Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	464,594	457,650	$ 405,968
Classified
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	96,685	116,104
Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	75,906	79,906
Classified | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	7,543	4,715
Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	12,794	31,044
Classified | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	442	439
Special Mention
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	463,994	391,611
Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	243,717	211,657
Special Mention | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	68,586	69,447
Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	145,200	108,666
Special Mention | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	6,491	1,841
Pass
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	27,099,362	22,433,833
Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	14,311,126	10,887,157
Pass | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	4,217,387	3,362,965
Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	8,113,188	7,728,341
Pass | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	457,661	455,370
Asset-based | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,154,654	4,075,477
Asset-based | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,127	4,591
Asset-based | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	79,991	78,305
Asset-based | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	5,072,536	3,992,581
Venture Capital Loans | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,001,086	2,320,593
Venture Capital Loans | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,803	4,794
Venture Capital Loans | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	56,974	14,833
Venture Capital Loans | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,940,309	2,300,966
Other Commercial | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,115,442	1,471,981
Other Commercial | Classified | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	6,864	21,659
Other Commercial | Special Mention | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	8,235	15,528
Other Commercial | Pass | Commercial
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,100,343	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	843,086	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	0	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	843,086	764,864
Residential Real Estate Construction Financing Receivable | Real Estate Construction and Land
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,450,430	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	7,543	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	68,586	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	3,374,301	2,598,101
Commercial | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,770,706	3,762,299
Commercial | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	44,014	62,206
Commercial | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	215,057	191,809
Commercial | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,511,635	3,508,284
Residential Real Estate [Member] | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	10,860,043	7,416,421
Residential Real Estate [Member] | Classified | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	31,892	17,700
Residential Real Estate [Member] | Special Mention | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	28,660	19,848
Residential Real Estate [Member] | Pass | Real Estate Mortgage
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 10,799,491	7,378,873
Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		$ 22,941,548