Loans Held for Investment - Summary of Nonaccrual Loans (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	$ 17,682,000	$ 17,682,000
ACL	557,000	557,000
Non-Collateral Dependent Loans	9,532,000	9,532,000
ACL	1,431,000	1,431,000
Total Nonaccrual Loans	27,214,000	27,214,000	$ 8,500,000
Nonaccrual Loans with No ACL	16,182,000	16,182,000
Interest income	0	0
Investor loans secured by real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	4,997,000	4,997,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	4,997,000	4,997,000
Nonaccrual Loans with No ACL	4,997,000	4,997,000
Investor loans secured by real estate \| CRE non-owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	2,838,000	2,838,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	2,838,000	2,838,000
Nonaccrual Loans with No ACL	2,838,000	2,838,000
Investor loans secured by real estate \| Construction and land
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	895,000	895,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	895,000	895,000
Nonaccrual Loans with No ACL	895,000	895,000
Investor loans secured by real estate \| SBA secured by real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	1,264,000	1,264,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	1,264,000	1,264,000
Nonaccrual Loans with No ACL	1,264,000	1,264,000
Business loans secured by real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	7,189,000	7,189,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	7,189,000	7,189,000
Nonaccrual Loans with No ACL	7,189,000	7,189,000
Business loans secured by real estate \| SBA secured by real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	1,084,000	1,084,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	1,084,000	1,084,000
Nonaccrual Loans with No ACL	1,084,000	1,084,000
Business loans secured by real estate \| CRE owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	6,105,000	6,105,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	6,105,000	6,105,000
Nonaccrual Loans with No ACL	6,105,000	6,105,000
Commercial loans
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	5,046,000	5,046,000
ACL	557,000	557,000
Non-Collateral Dependent Loans	9,532,000	9,532,000
ACL	1,431,000	1,431,000
Total Nonaccrual Loans	14,578,000	14,578,000
Nonaccrual Loans with No ACL	3,546,000	3,546,000
Commercial loans \| Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	4,309,000	4,309,000
ACL	557,000	557,000
Non-Collateral Dependent Loans	1,790,000	1,790,000
ACL	266,000	266,000
Total Nonaccrual Loans	6,099,000	6,099,000
Nonaccrual Loans with No ACL	2,809,000	2,809,000
Commercial loans \| Franchise non-real estate secured
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	0	0
ACL	0	0
Non-Collateral Dependent Loans	7,742,000	7,742,000
ACL	1,165,000	1,165,000
Total Nonaccrual Loans	7,742,000	7,742,000
Nonaccrual Loans with No ACL	0	0
Commercial loans \| SBA non-real estate secured
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	737,000	737,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	737,000	737,000
Nonaccrual Loans with No ACL	737,000	737,000
Retail loans
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	450,000	450,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	450,000	450,000
Nonaccrual Loans with No ACL	450,000	450,000
Retail loans \| Single family residential
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	450,000	450,000
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	450,000	450,000
Nonaccrual Loans with No ACL	$ 450,000	$ 450,000

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