Loans Held for Investment - Aging (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	$ 7,944,246	$ 7,879,904
Accruing Loans Past Due 90 Days or More	102	101
Financing Receivables, 30 to 59 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	7,761	10,477
Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,446	3,725
Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	13,625	21,950
Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	22,832	36,152
Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	7,921,414	7,843,752
Prime Lending
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Repurchase under a forbearance agreement	49,000
Prime Lending | U S Government Agencies Secured
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Accruing Loans Past Due 90 Days or More	96,400	60,700
Unpaid principal balance loans past due 90 days or more	96,900	61,700
Commercial real estate
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	3,313,911	3,042,729
Commercial real estate | Non-owner occupied
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,954,231	1,729,699
Commercial real estate | Non-owner occupied | Financing Receivables, 30 to 59 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans		117
Commercial real estate | Non-owner occupied | Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	234	1,173
Commercial real estate | Non-owner occupied | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	234	1,290
Commercial real estate | Non-owner occupied | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,953,997	1,728,409
Commercial real estate | Owner occupied
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,359,680	1,313,030
Commercial real estate | Owner occupied | Financing Receivables, 30 to 59 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	329	590
Commercial real estate | Owner occupied | Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans		688
Commercial real estate | Owner occupied | Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans		2,273
Commercial real estate | Owner occupied | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	329	3,551
Commercial real estate | Owner occupied | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,359,351	1,309,479
Commercial and industrial
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,668,209	1,875,420
Accruing Loans Past Due 90 Days or More		1
Commercial and industrial | Financing Receivables, 30 to 59 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	3,597	1,059
Commercial and industrial | Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	8	277
Commercial and industrial | Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	8,329	13,640
Commercial and industrial | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	11,934	14,976
Commercial and industrial | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,656,275	1,860,444
Construction and Land Development
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	934,915	892,783
Construction and Land Development | Financing Receivables, 30 to 59 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1	946
Construction and Land Development | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1	946
Construction and Land Development | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	934,914	891,837
1 - 4 family residential
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,595,270	1,303,430
Accruing Loans Past Due 90 Days or More	102	100
1 - 4 family residential | Financing Receivables, 30 to 59 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	3,687	7,642
1 - 4 family residential | Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,431	2,738
1 - 4 family residential | Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	5,046	4,842
1 - 4 family residential | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	10,164	15,222
1 - 4 family residential | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,585,106	1,288,208
Consumer
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	29,439	32,349
Consumer | Financing Receivables, 30 to 59 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	147	123
Consumer | Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	7	22
Consumer | Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	16	22
Consumer | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	170	167
Consumer | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	29,269	32,182
Broker-dealer
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	402,502	733,193
Broker-dealer | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	$ 402,502	$ 733,193