Changes in Accumulated Other Comprehensive Income (Loss) by Component (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				$ 1,675.1
Other comprehensive income (loss) before reclassifications				64.1	$ (22.9)
Tax (provision) benefit	[1]			(1.1)	8.5
Other comprehensive income (loss) before reclassifications, net of taxes				63.0	(14.4)
Reclassifications				13.9	14.4
Tax provision (benefit)				(3.4)	(2.6)
Reclassifications, net of tax				10.5	11.8
Other comprehensive income (loss)		$ 33.1	$ (11.2)	73.5	(2.6)
Ending balance		2,017.9		2,017.9
Derivative Instruments Designated as Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				(9.9)	(8.7)
Other comprehensive income (loss) before reclassifications				(0.6)	(31.1)
Tax (provision) benefit	[1]			1.9	8.5
Other comprehensive income (loss) before reclassifications, net of taxes				1.3	(22.6)
Reclassifications	[2]			4.1	6.6
Tax provision (benefit)				0.0	0.1
Reclassifications, net of tax				4.1	6.7
Other comprehensive income (loss)				5.4	(15.9)
Ending balance		(4.5)	(24.6)	(4.5)	(24.6)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				(116.0)	(94.2)
Other comprehensive income (loss) before reclassifications				55.3	8.2
Tax (provision) benefit	[1]			0.0	0.0
Other comprehensive income (loss) before reclassifications, net of taxes				55.3	8.2
Reclassifications				0.0	0.0
Tax provision (benefit)				0.0	0.0
Reclassifications, net of tax				0.0	0.0
Other comprehensive income (loss)				55.3	8.2
Ending balance		(60.7)	(86.0)	(60.7)	(86.0)
Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				(109.6)	(105.1)
Other comprehensive income (loss) before reclassifications				9.4	0.0
Tax (provision) benefit	[1]			(3.0)	0.0
Other comprehensive income (loss) before reclassifications, net of taxes				6.4	0.0
Reclassifications	[3]			9.8	7.8
Tax provision (benefit)				(3.4)	(2.7)
Reclassifications, net of tax				6.4	5.1
Other comprehensive income (loss)				12.8	5.1
Ending balance		(96.8)	(100.0)	(96.8)	(100.0)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				(235.5)	(208.0)
Ending balance		$ (162.0)	$ (210.6)	$ (162.0)	$ (210.6)

[1] Income taxes are not provided for foreign currency translation adjustment.

[2] See Note 6 of the notes to condensed consolidated financial statements.

[3] These components are included in the computation of net periodic pension cost. See Note 10 of the notes to condensed consolidated financial statements.