Income Taxes - Unrecognized Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unrecognized Tax Benefit Activity [Roll Forward]
Beginning balance	$ 448	$ 0	$ 0
Additions based on tax positions related to the current year	1,578	448	0
Additions (reductions) for tax positions of prior years	(340)	0	0
Statute of limitations expiration	0	0	0
Settlements	0	0	0
Ending balance	$ 1,686	$ 448	$ 0