Fair Value Measurements and the Fair Value Option - Schedule of Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unconsolidated investments	$ 478.3	$ 380.7
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unconsolidated investments	478.3	380.7
Marketable securities		7.5
Total	426.7	287.3
Recurring [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net currency derivative contracts	(51.6)	(100.9)
Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unconsolidated investments	0.0	0.0
Marketable securities		7.5
Total	0.0	7.5
Recurring [Member] | Level 1 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net currency derivative contracts	0.0	0.0
Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unconsolidated investments	0.0	0.0
Marketable securities		0.0
Total	(51.6)	(100.9)
Recurring [Member] | Level 2 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net currency derivative contracts	(51.6)	(100.9)
Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unconsolidated investments	478.3	380.7
Marketable securities		0.0
Total	478.3	380.7
Recurring [Member] | Level 3 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net currency derivative contracts	$ 0.0	$ 0.0