Taxation (Summary of (Provision) Benefit for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Federal	$ (221.0)	$ (227.5)	$ (149.3)
State	(23.4)	(31.3)	(22.0)
Foreign	(161.4)	(161.2)	(129.9)
Current income tax (provision)	(405.8)	(420.0)	(301.2)
Federal	11.9	26.8	(24.1)
State	(5.2)	1.0	(7.4)
Foreign	1.1	1.6	(4.2)
Deferred income tax (provision)	7.8	29.4	(35.7)
Total income tax (provision)	$ (398.0)	$ (390.6)	$ (336.9)