Fair Value Measurements Fair Value Measurements, Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Net Asset (Liability)	$ (14.6)		$ (11.1)
(Decrease)/increase in diluted earnings per share resulting from adjustment		$ (0.00)
Weighted-average credit-adjusted risk-free rate	8.70%
Minimum
Schedule of Available-for-sale Securities [Line Items]
Short Term Investment Maturity Period	1 month
Maximum
Schedule of Available-for-sale Securities [Line Items]
Short Term Investment Maturity Period	3 months