Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Depreciation and amortization expense on property and equipment	$ 600	$ 500	$ 200
Accrued Liabilities, Current	7,394	$ 4,274
Accrued expenses
Accrued Liabilities, Current	$ 400