Loans Held for Investment - Aging (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	$ 7,930,619	$ 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	21,294	10,477
Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,777	3,725
Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	14,200	21,950
Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	37,271	36,152
Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	7,893,348	7,843,752
Prime Lending
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Repurchase under a forbearance agreement	36,100
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	82,300	60,700
Unpaid principal balance loans past due 90 days or more	82,800	61,700
Commercial real estate
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	3,262,628	3,042,729
Commercial real estate | Non-owner occupied
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,911,136	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	198	1,173
Commercial real estate | Non-owner occupied | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	198	1,290
Commercial real estate | Non-owner occupied | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,910,938	1,728,409
Commercial real estate | Owner occupied
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,351,492	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	3,020	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	36	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	83	2,273
Commercial real estate | Owner occupied | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	3,139	3,551
Commercial real estate | Owner occupied | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,348,353	1,309,479
Commercial and industrial
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,786,116	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	9,086	1,059
Commercial and industrial | Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	59	277
Commercial and industrial | Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	8,025	13,640
Commercial and industrial | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	17,170	14,976
Commercial and industrial | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,768,946	1,860,444
Construction and Land Development
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	922,047	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	4,288	946
Construction and Land Development | Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	116
Construction and Land Development | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	4,404	946
Construction and Land Development | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	917,643	891,837
1 - 4 family residential
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,468,962	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	4,709	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	1,551	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	5,876	4,842
1 - 4 family residential | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	12,136	15,222
1 - 4 family residential | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	1,456,826	1,288,208
Consumer
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	27,862	32,349
Consumer | Financing Receivables, 30 to 59 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	191	123
Consumer | Financing Receivables, 60 to 89 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	15	22
Consumer | Financing Receivables, Greater than 90 Days Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	18	22
Consumer | Financial Asset, Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	224	167
Consumer | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	27,638	32,182
Broker-dealer
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	463,004	733,193
Broker-dealer | Financial Asset, Not Past Due
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans	$ 463,004	$ 733,193