Income Taxes - Components of the provision for income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Domestic
Current	$ 1,615	$ 891	$ 3,706
Deferred	5,992	10,864	21,880
Foreign
Deferred			(2)
Total income tax expense	$ 7,607	$ 11,755	$ 25,584