Fair Value Measurements (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unrealized gains included in earnings	$ 0	$ 2.9
Unrealized losses included in earnings	(2.4)	(1.2)
Fair Value, Measurements, Recurring | Venture capital investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, beginning of period			14.5	21.9
Fair value, end of period	$ 12.1	$ 23.6	$ 14.5	$ 21.9