Changes in Accumulated Other Comprehensive Loss by Component - Reconciliation of Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Gain/(Loss) by Component, beginning balance	$ (71.6)
Beginning balance	1,848.2	$ 396.7
Net current-period Other Comprehensive Income Gain/(Loss)	(10.4)	(6.8)
Reclassification adjustment from loss on partial settlement of pension plan, net of tax		3.8
Accumulated Other Comprehensive Gain/(Loss) by Component, ending balance	(82.0)
Ending balance	1,884.4	412.9
Gains and Losses on Cash Flow Hedges [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Gain/(Loss) by Component, beginning balance	(12.9)	(0.5)
Net current-period Other Comprehensive Income Gain/(Loss)	(2.5)	1.1
Reclassification adjustment from loss on partial settlement of pension plan, net of tax		0.0
Accumulated Other Comprehensive Gain/(Loss) by Component, ending balance	(15.4)	0.6
Defined Benefit Pension Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Gain/(Loss) by Component, beginning balance	(0.2)	(3.7)
Net current-period Other Comprehensive Income Gain/(Loss)	(0.3)	0.6
Reclassification adjustment from loss on partial settlement of pension plan, net of tax		3.8
Accumulated Other Comprehensive Gain/(Loss) by Component, ending balance	(0.5)	0.7
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Gain/(Loss) by Component, beginning balance	(58.5)	(45.7)
Net current-period Other Comprehensive Income Gain/(Loss)	(7.6)	(8.5)
Reclassification adjustment from loss on partial settlement of pension plan, net of tax		0.0
Accumulated Other Comprehensive Gain/(Loss) by Component, ending balance	(66.1)	(54.2)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(71.6)	(49.9)
Ending balance	$ (82.0)	$ (52.9)

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

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Amount, after tax, of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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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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