Financial Instruments - Changes in AOCI Related to Cash Flow Hedges (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Change in AOCI [Roll Forward]
Balance, beginning			$ (85.7)
Other comprehensive income (loss)	$ (7.8)	$ 13.6	(18.5)	$ 44.9
Balance, ending	(110.7)		(110.7)
Accumulated Foreign Currency Adjustment
Change in AOCI [Roll Forward]
Balance, beginning	(3.5)	0.2	(4.0)	0.9
Other comprehensive income (loss) before reclassifications	(0.1)	(0.2)	0.2	(0.4)
Amounts reclassified from accumulated other comprehensive loss	0.1	0.0	0.3	(0.5)
Other comprehensive income (loss)	0.0	(0.2)	0.5	(0.9)
Balance, ending	$ (3.5)	$ 0.0	$ (3.5)	$ 0.0

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

No definition available.

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- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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

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