v3.10.0.1

Changes in Accumulated Other Comprehensive Income by Component - Summary of Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) as of December 31, 2017			$ 7,958.8
Other comprehensive income before reclassifications			31.2
Amounts reclassified from accumulated other comprehensive income	$ (0.8)	$ 1.7	(1.0)	$ 3.1
Other comprehensive income (loss), net of tax	11.1	$ (2.4)	30.2	$ (3.1)
Accumulated other comprehensive income (loss) as of June 30, 2018	7,846.1		7,846.1
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) as of December 31, 2017			1.4
Other comprehensive income before reclassifications			31.2
Amounts reclassified from accumulated other comprehensive income			(1.0)
Other comprehensive income (loss), net of tax			30.2
Accumulated other comprehensive income (loss) as of June 30, 2018	31.6		31.6
Defined Benefit Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) as of December 31, 2017			21.2
Other comprehensive income before reclassifications			0.0
Amounts reclassified from accumulated other comprehensive income			0.0
Other comprehensive income (loss), net of tax			0.0
Accumulated other comprehensive income (loss) as of June 30, 2018	21.2		21.2
Accumulated Other Comprehensive Loss, Net of Tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) as of December 31, 2017			22.6
Other comprehensive income (loss), net of tax			30.2
Accumulated other comprehensive income (loss) as of June 30, 2018	$ 52.8		$ 52.8

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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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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