Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Non-financial assets and liabilities measured at fair value on a nonrecurring basis	$ 0.0	$ 0.0	$ 0.0
Decrease in fair value of marketable securities	$ (1.1)	$ (0.7)