Restructuring Charges (Details) - USD ($) $ in Millions	1 Months Ended			12 Months Ended
	Sep. 30, 2016	May 31, 2014	Feb. 28, 2014	Dec. 31, 2016	Dec. 31, 2014
Restructuring And Related Activities [Abstract]
Percentage reduction in workforce	13.00%	10.00%	18.00%
Employee severance and termination benefits				$ 1.1	$ 1.4