Income Taxes - Summary of income tax provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current
Federal	$ 6,976	$ 5,155	$ 7,020
State	3,562	3,310	1,557
Current income tax provision	10,538	8,465	8,577
Deferred
Federal	3,010	4,936	(1,453)
Foreign	874	(822)	(875)
State	(194)	(805)	(2,763)
Deferred income tax provision (benefit)	3,690	3,309	(5,091)
Income tax expense	$ 14,228	$ 11,774	$ 3,486