Debt (Details 1) - Convertible subordinated notes - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Debt Instrument [Line Items]
Coupon rate interest	$ 4.4	$ 4.4	$ 13.1	$ 13.1
Amortized debt discount	4.0	3.7	11.7	10.8
Total interest expense recognized on the Convertible Subordinated Notes	$ 8.4	$ 8.1	$ 24.8	$ 23.9