Fair Value Measurements and Risk - Gain (Loss) on Derivative Instruments (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gains and losses on derivative instruments
Interest and Debt Expense	$ (76.7)	$ (80.2)	$ (79.5)
Nonoperating Income (Expense)	(80.6)	18.4	(27.1)
Derivatives in ASC 815 cash flow hedging relationships
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	21.1	46.6	(2.7)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	26.8	55.9	(5.6)
Derivatives in ASC 815 cash flow hedging relationships | Interest Rate Contract [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	(2.9)	0.4	0.9
Derivatives in ASC 815 cash flow hedging relationships | Interest Rate Contract [Member] | Interest Expense [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	(0.3)	(0.6)	(2.7)
Derivatives in ASC 815 cash flow hedging relationships | Cross Currency Interest Rate Contract [Member] | Interest Expense [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	9.1	(0.6)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	13.2	9.7	0.0
Derivatives in ASC 815 cash flow hedging relationships | Cross Currency Interest Rate Contract [Member] | Nonoperating Income (Expense) [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	12.5	40.5
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	12.5	40.5	0.0
Derivatives in ASC 815 cash flow hedging relationships | Currency contracts
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	2.4	6.3	(3.6)
Derivatives in ASC 815 cash flow hedging relationships | Currency contracts | Nonoperating Income (Expense) [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	1.4	6.3	(2.9)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	2.8	3.0	0.6
Not Designated as Hedging Instrument [Member] | Currency contracts | Nonoperating Income (Expense) [Member]
Gains and losses on derivative instruments
Derivative Instruments, Gain (Loss) Recognized in Income, Net	(0.4)	(4.0)	1.0
AOCI, Derivative Qualifying as Hedge, Excluded Component, Parent [Member] | Derivatives in ASC 815 cash flow hedging relationships | Currency contracts
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	$ 0.6	$ (0.4)	$ (0.6)