Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Components of provision for income taxes
Income tax expense	$ 619	$ 948	$ 1,761	$ 3,483
Current foreign tax expense	125	415	486	2,018
Current federal tax expense	(6)	(59)	30	32
Current state tax expense	$ 500	$ 592	$ 1,245	$ 1,433