(Components of AOCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Balance, beginning	$ (186.8)	$ (162.6)
Other comprehensive (loss) income before reclassifications	66.8	(28.7)
Amounts reclassified from AOCI	2.7	4.5
Other comprehensive income (loss), net of tax	69.5	(24.2)	$ (43.4)
Balance, ending	(117.3)	(186.8)	(162.6)
Losses on Cash Flow Hedges [Member]
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Balance, beginning	(3.2)	(3.1)
Other comprehensive (loss) income before reclassifications	(3.6)	(1.2)
Amounts reclassified from AOCI	2.6	1.1
Other comprehensive income (loss), net of tax	(1.0)	(0.1)
Balance, ending	(4.2)	(3.2)	(3.1)
Unrealized Gains on Investment Securities [Member]
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Balance, beginning	5.2	5.4
Other comprehensive (loss) income before reclassifications	(4.7)	(0.2)
Amounts reclassified from AOCI	0.0	0.0
Other comprehensive income (loss), net of tax	(4.7)	(0.2)
Balance, ending	0.5	5.2	5.4
Defined Benefit Pension and Other Postretirement Plans [Member]
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Balance, beginning	(45.4)	(39.6)
Other comprehensive (loss) income before reclassifications	6.3	(9.2)
Amounts reclassified from AOCI	0.1	3.4
Other comprehensive income (loss), net of tax	6.4	(5.8)
Balance, ending	(39.0)	(45.4)	(39.6)
Foreign Currency Translation [Member]
Changes in the Components of Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Balance, beginning	(143.4)	(125.3)
Other comprehensive (loss) income before reclassifications	68.8	(18.1)
Amounts reclassified from AOCI	0.0	0.0
Other comprehensive income (loss), net of tax	68.8	(18.1)
Balance, ending	$ (74.6)	$ (143.4)	$ (125.3)