Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 2,404.3	$ 77.6	$ 443.3
Foreign currency translation	(1.0)	(0.5)	8.4
Unrealized gains (losses) on debt securities	0.2	(0.5)	0.6
Unrealized gains (losses) on pension obligation	(6.6)	2.2	1.9
Unrealized gains (losses) on hedging activities, net of tax of $(14.5), $7.3 and $(59.0), respectively	(49.7)	23.5	(105.8)
Other comprehensive income (loss), net of tax	(57.1)	24.7	(94.9)
Comprehensive income	$ 2,347.2	$ 102.3	$ 348.4