Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Components of provision for income taxes
Income tax expense	$ 786	$ 2,160	$ 1,142	$ 2,535
Current foreign tax expense	246	1,570	361	1,602
Current federal tax expense	25	39	36	92
Current state tax expense	$ 515	$ 551	$ 745	$ 841