Income Taxes - Additional Tax Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income taxes
Tax bad debt deduction under the new method	$ 4,300
Taxable income evenly term	4 years
Unrecognized tax benefits if recognized would favorably affect income tax provision in future	$ 475	$ 475
Interest accrued during the period related to unrecognized tax benefits	8	$ 5
Federal
Income taxes
Net operating loss carryforwards	7,200
Federal | General Business Tax Credit Carryforward
Income taxes
Tax credit carryforward	1,800
Federal | Alternative Minimum Tax Credit Carryforward
Income taxes
Tax credit carryforward	59
California
Income taxes
Net operating loss carryforwards	$ 24,500