Income Taxes - Schedule of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Beginning balance	$ 5,698	$ 2,604	$ 1,353
Increases in tax positions for prior years	5	0	0
Decreases in tax positions for prior years	0	(196)	(14)
Increases in tax positions for current year	1,187	3,365	1,265
Lapse in statute of limitations	0	(75)	0
Ending Balance	$ 6,890	$ 5,698	$ 2,604