Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Cash and cash equivalents	$ 11,346	$ 11,631	$ 8,116	$ 13,200
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3.7	4.5