Income Taxes - Unrecognized Tax Benefit Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, beginning balance	$ 820	$ 1,185	$ 400
Increase attributable to tax positions taken during a prior period	216		925
Decrease attributable to settlements with taxing authorities	(37)
Decrease attributable to lapse of statute of limitations	(783)	(365)	(140)
Unrecognized tax benefits, ending balance	$ 216	$ 820	$ 1,185