Accumulated Other Comprehensive (Loss) Income Amount of Income Tax (Expense) Benefit Allocated to Component of Other Comprehensive Income (Loss) (Footnote) (Details) - USD ($) $ in Millions		12 Months Ended
	Dec. 18, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
1.875% Senior Notes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax		$ 26.1	$ 50.9
1.875% Senior Notes | Net Investment Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax				$ 12.8
Forward Contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax	$ 5.2
Forward Contracts | Net Investment Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax				5.2
JP Morgan | Interest Rate Swap | Interest Rate Swap
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax				$ (33.4)