Long-Term and Other Debt - (Loss) Gain on Debt Financing Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Debt Disclosure [Abstract]
Repurchase and cancellation of principal balance at discount	$ 0.0	$ 0.0	$ 0.0	$ 26.0
Unamortized debt discount and deferred financing costs	(0.6)	0.0	(26.4)	(0.8)
Third party debt issuance fees	(7.8)	0.0	(11.7)	0.0
Total (loss) gain on debt financing transactions	$ (8.4)	$ 0.0	$ (38.1)	$ 25.2