Reconciliation of Segment Operating Income to Consolidated Income (Loss) Before Income Taxes (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating profit (loss)		$ (49.5)	$ 15.8	$ (79.5)	$ (4.1)
Interest expense		(2.7)	(2.3)	(5.3)	(4.3)
Other income (expense), net		1.4	(2.5)	6.3	(12.3)
Cost reduction charges	$ (300.0)	(52.6)		(52.6)
Income (loss) before income taxes		(50.8)	11.0	(78.5)	(20.7)
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating profit (loss)		33.8	30.5	29.9	26.8
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating profit (loss)		$ (30.7)	$ (14.7)	$ (56.8)	$ (30.9)