Changes in Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
January 1	$ (191.6)	$ (129.5)
Other comprehensive income (loss) before reclassifications	(403.3)	(83.1)
Amounts reclassified from accumulated other comprehensive income (loss)	(23.3)	21.0
Other comprehensive income (loss)	(426.6)	(62.1)
December 31	(618.2)	(191.6)
Unrealized Gain (Loss) on Available-for-Sale Securities
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
January 1	(1.6)	(2.0)
Other comprehensive income (loss) before reclassifications	0.4	0.4
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive income (loss)	0.4	0.4
December 31	(1.2)	(1.6)
Defined Benefit Pension and Postemployment Plans
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
January 1	(68.8)	(89.8)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	(23.3)	21.0
Other comprehensive income (loss)	(23.3)	21.0
December 31	(92.1)	(68.8)
Defined Benefit Pension and Postemployment Plans | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Abstract]
Prior service cost	6.4	5.5
Actuarial (gains) losses	3.2	5.0
Net periodic benefit cost (see Note 12)	9.6	10.5
Income taxes	3.8	4.2
Periodic benefit cost, net of income tax	5.8	6.3
Foreign Currency Translation
Changes in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
January 1	(121.2)	(37.7)
Other comprehensive income (loss) before reclassifications	(403.7)	(83.5)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive income (loss)	(403.7)	(83.5)
December 31	$ (524.9)	$ (121.2)