Restructuring - Summary of Restructuring Activities (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Current year charges	$ 107.0us-gaap_RestructuringCharges	$ 77.9us-gaap_RestructuringCharges	$ 55.1us-gaap_RestructuringCharges
Restructuring charges excluding pension opeb charges
Restructuring Cost and Reserve [Line Items]
Accrual as of beginning of period	44.3	44.2	62.5
Current year charges	107.0	75.4	55.1
Utilization cash	(100.6)	(66.1)	(67.4)
Utilization non-cash	(0.5)	(9.2)	(6.0)
Accrual as of end of period	50.2	44.3	44.2
Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Accrual as of beginning of period	38.7	38.5	56.8
Current year charges	88.6	54.1	45.4
Utilization cash		(53.9)	(63.7)
Accrual as of end of period		38.7	38.5
Employee termination benefits \| Restructuring charges excluding pension opeb charges
Restructuring Cost and Reserve [Line Items]
Accrual as of beginning of period	38.7
Utilization cash	(82.2)
Accrual as of end of period	45.1
Asset impairments
Restructuring Cost and Reserve [Line Items]
Current year charges	0.5	9.2	6.0
Utilization non-cash	(0.5)	(9.2)	(6.0)
Contract termination costs
Restructuring Cost and Reserve [Line Items]
Current year charges	0.5	2.8	1.9
Contract termination costs \| Restructuring charges excluding pension opeb charges
Restructuring Cost and Reserve [Line Items]
Accrual as of beginning of period	5.6	5.7	5.7
Current year charges	0.5	0.3	1.9
Utilization cash	(1.0)	(0.4)	(1.9)
Accrual as of end of period	5.1	5.6	5.7
Other related costs
Restructuring Cost and Reserve [Line Items]
Current year charges	17.4	11.8	1.8
Utilization cash	$ (17.4)	$ (11.8)	$ (1.8)

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

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Amount of consideration other than cash used to fully or partially settle an accrued restructuring cost.

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