Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	$ 6,170.5
Balance at March 31, 2018	6,205.4
Foreign currency translation adjustments
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	260.6
OCI before reclassifications	73.0
Amounts reclassified from AOCI	0.0
Other comprehensive income	73.0
Balance at March 31, 2018	333.6
Fair value of derivative financial instruments, net of tax
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	(9.8)
OCI before reclassifications	(0.1)
Amounts reclassified from AOCI	(0.5)
Other comprehensive income	(0.6)
Balance at March 31, 2018	(10.4)
Fair value of investment securities, net of tax
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	1.0
OCI before reclassifications	0.0
Amounts reclassified from AOCI	0.0
Other comprehensive income	0.0
Balance at March 31, 2018	0.0
Post-retirement and pension liability adjustments, net of tax
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	1.3
OCI before reclassifications	(0.2)
Amounts reclassified from AOCI	0.0
Other comprehensive income	(0.2)
Balance at March 31, 2018	1.1
AOCI Attributable to Parent
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	253.1
OCI before reclassifications	72.7
Amounts reclassified from AOCI	(0.5)
Other comprehensive income	72.2
Balance at March 31, 2018	324.3
ASU 2016-01 | Foreign currency translation adjustments
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	260.6
ASU 2016-01 adoption impact		$ 0.0
ASU 2016-01 | Fair value of derivative financial instruments, net of tax
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	(9.8)
ASU 2016-01 adoption impact		0.0
ASU 2016-01 | Fair value of investment securities, net of tax
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	0.0
ASU 2016-01 adoption impact		(1.0)
ASU 2016-01 | Post-retirement and pension liability adjustments, net of tax
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	1.3
ASU 2016-01 adoption impact		0.0
ASU 2016-01 | AOCI Attributable to Parent
Accumulated Other Comprehensive Income [Roll Forward]
Balance at December 31, 2017	$ 252.1
ASU 2016-01 adoption impact		$ (1.0)