Segments - Geographic (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Total net revenues	$ 1,204.1	$ 1,308.9	$ 2,286.7	$ 2,529.9
Total Americas
Segment Reporting Information [Line Items]
Total net revenues	675.7	800.8	1,263.3	1,512.4
United States
Segment Reporting Information [Line Items]
Total net revenues	624.8	749.1	1,157.1	1,407.2
Other
Segment Reporting Information [Line Items]
Total net revenues	50.9	51.7	106.2	105.2
Europe, Middle East, and Africa
Segment Reporting Information [Line Items]
Total net revenues	308.9	288.2	616.9	572.7
Asia Pacific
Segment Reporting Information [Line Items]
Total net revenues	$ 219.5	$ 219.9	$ 406.5	$ 444.8