Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Foreign currency translation adjustment:
Balance at beginning of period	$ (585.3)	$ (718.6)
Other comprehensive income before reclassifications	(92.2)	85.2
Amount reclassified from accumulated other comprehensive loss, net of tax	13.4	0.3
Balance at end of period	(664.1)	(633.1)
Available-for-sale securities:
Balance at beginning of period		0.6
Other comprehensive income before reclassifications		0.1
Amount reclassified from accumulated other comprehensive loss, net of tax		0.0
Balance at end of period		0.7
Derivative instruments:
Balance at beginning of period	(6.8)	(8.4)
Other comprehensive income before reclassifications	0.0	0.0
Amount reclassified from accumulated other comprehensive loss, net of tax	0.8	0.7
Balance at end of period	(6.0)	(7.7)
Defined benefit pension and other postretirement plans:
Balance at beginning of period	(235.7)	(238.0)
Other comprehensive income before reclassifications	(0.9)	0.4
Amount reclassified from accumulated other comprehensive loss,net of tax	3.3	2.7
Balance at end of period	(233.3)	(234.9)
Total:
Balance at beginning of period	(827.8)	(964.4)
Other comprehensive income before reclassifications	(93.1)	85.7
Amount reclassified from accumulated other comprehensive loss, net of tax	17.5	3.7
Balance at end of period	$ (903.4)	$ (875.0)