401(k) Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution amount	$ 0.4	$ 0.5	$ 0.4
Minimum
Defined Benefit Plan Disclosure [Line Items]
Minimum employee eligibility age (years)	18 years