Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	$ 2,347.4	$ 2,205.0	$ 2,205.0
Other comprehensive income (loss)	10.4	(20.0)	(25.3)
Balance at the end of the period	2,387.5		2,347.4
Accrued post-retirement benefit liability
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	(27.4)	(32.0)	(32.0)
Amounts reclassified from accumulated other comprehensive loss	0.6	1.3
Income tax benefit (expense)	(0.2)	(0.5)
Other comprehensive income (loss)	0.4	0.8
Balance at the end of the period	(27.0)	(31.2)	(27.4)
Foreign currency translation
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	(60.0)	(30.4)	(30.4)
Other comprehensive loss before reclassifications	10.2	(20.7)
Other comprehensive income (loss)	10.2	(20.7)
Balance at the end of the period	(49.8)	(51.1)	(60.0)
Hedging activities
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	0.3	0.6	0.6
Amounts reclassified from accumulated other comprehensive loss	(0.3)	(0.2)
Income tax benefit (expense)	0.1	0.1
Other comprehensive income (loss)	(0.2)	(0.1)
Balance at the end of the period	0.1	0.5	0.3
Accumulated Other Comprehensive Income (loss).
Accumulated balances for each classification of comprehensive income (loss)
Balance at the beginning of the period	(87.1)	(61.8)	(61.8)
Other comprehensive loss before reclassifications	10.2	(20.7)
Amounts reclassified from accumulated other comprehensive loss	0.3	1.1
Income tax benefit (expense)	(0.1)	(0.4)
Other comprehensive income (loss)	10.4	(20.0)	(25.3)
Balance at the end of the period	$ (76.7)	$ (81.8)	$ (87.1)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
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Amount of tax expense (benefit) allocated to other comprehensive income (loss) attributable to parent entity.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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