Income Taxes - Expense (benefit) reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Statutory federal income tax rate (as a percent)	21.00%	21.00%	35.00%
Tax at the federal statutory rate	$ 7,607	$ 6,643	$ 14,594
State income taxes (net of federal benefit)	1,477	1,392	1,340
Decrease in valuation allowance		(4,993)	(142)
Decrease in uncertain tax positions		(2,165)
Change in US and State tax rates	1,006	(1,035)	(33,542)
Benefit of Qualified Opportunity Zone investment	(561)
Dividend received deduction	(188)	(322)	(530)
Other permanent items	106	(256)	399
Total income tax expense (benefit)	$ 9,447	$ (736)	$ (17,881)