401(k) Profit-Sharing Plan (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2011	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
401(k) Profit-Sharing Plan [Abstract]
Participating employees maximum compensation deferral percentage	75.00%
Employee contributions matching percentage	6.00%
Expensed employer matching contributions		$ 0.2	$ 0.3	$ 0.3
Employer matching contributions disbursements		$ 0.3	$ 0.3