Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Components of provision for income taxes
Income tax expense	$ 771	$ 786	$ 1,242	$ 1,142
Current foreign tax expense	211	246	340	361
Current federal tax expense		25		36
Current state tax expense	$ 560	$ 515	$ 902	$ 745