Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of year	$ 1,180	$ 1,359	$ 1,884
Additions based on tax positions related to the current year	331	239	230
Additions for tax positions of prior years	41	39	46
Reductions for tax positions of prior years	0	0	(437)
Settlements or lapse of statute of limitations	(308)	(457)	(364)
Balance at end of year	$ 1,244	$ 1,180	$ 1,359