Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Increase (decrease) in deferred tax asset valuation allowance		$ (20,700)	$ 1,900	$ 1,200
Interest and penalties recognize in income tax expense		31	35	$ 24
Interest and penalties recognized on the balance sheet	$ 323	323	$ 292
Unrecognized tax benefits that would impact effective tax rate	400	400
Tax Cuts and Jobs Act of 2017, change in deferred tax assets	34,100	34,100
Tax Cuts and Jobs Act of 2017, increase to deferred tax asset	34,300
India
Income Taxes [Line Items]
Deferred tax liability from undistributed foreign earnings	$ 100	$ 100