Reconciliation of Segment Operating Income to Consolidated Income Before Income Taxes (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating profit (loss)		$ 8.6	$ 76.6	$ (70.9)	$ 72.5
Interest expense		(3.0)	(2.3)	(8.3)	(6.6)
Other income (expense), net		1.7	3.3	8.0	(9.0)
Cost reduction charges	$ (300.0)	(17.4)		(70.0)
Income (loss) before income taxes		7.3	77.6	(71.2)	56.9
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating profit (loss)		51.5	92.2	81.4	119.0
Corporate and eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating profit (loss)		$ (25.5)	$ (15.6)	$ (82.3)	$ (46.5)