Changes in Accumulated Other Comprehensive Income/(Loss) by Component - Reconciliation of Changes in Accumulated Other Comprehensive Income/(Loss) by Component (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss) by Component	$ (89.9)
Beginning balance	1,922.3	$ 1,848.2
Net current-period Other Comprehensive Income (Loss)	(10.2)	(10.4)
Accumulated Other Comprehensive Income (Loss) by Component	(100.1)
Ending balance	1,808.5	1,884.4
Gains and Losses on Cash Flow Hedges [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss) by Component	(3.0)	(12.9)
Net current-period Other Comprehensive Income (Loss)	19.3	(2.5)
Accumulated Other Comprehensive Income (Loss) by Component	16.3	(15.4)
Non-cash Amortization of Interest Rate Swap Expense [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Net current-period Other Comprehensive Income (Loss)	1.7
Accumulated Other Comprehensive Income (Loss) by Component	1.7
Defined Benefit Pension Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss) by Component	(1.5)	(0.2)
Net current-period Other Comprehensive Income (Loss)	(0.1)	(0.3)
Accumulated Other Comprehensive Income (Loss) by Component	(1.6)	(0.5)
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss) by Component	(85.4)	(58.5)
Net current-period Other Comprehensive Income (Loss)	(31.1)	(7.6)
Accumulated Other Comprehensive Income (Loss) by Component	(116.5)	(66.1)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(89.9)	(71.6)
Ending balance	$ (100.1)	$ (82.0)

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.

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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