Commitments and Contingencies - Roll forward of Asbestos Liability and Related Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes in estimate during the period:
Asbestos-related liability	$ 77.1	$ 76.8
Asbestos-related current assets	64.7	66.0
Noncurrent portion	800.1	877.5
Noncurrent Asbestos Related Assets	304.0	314.6
Asbestos Related Matters [Member]
Liability for Asbestos and Environmental Claims, Net [Roll Forward]
Net Balance, Beginning	573.7	630.8
Changes in estimate during the period:
Continuing operations	(56.5)	(59.0)
Asbestos remeasurement	(76.4)	(81.8)
Settlement Agreement	0.0	2.1
Change in Defense Cost Estimate for Asbestos Matters	0.0	4.9
Net cash activity	(45.3)	(31.5)
Balance, Ending		573.7
Estimated asbestos exposure, net of expected recoveries from insurers and other responsible parties	508.5	573.7
Asbestos Related Matters [Member] | Liability [Member]
Liability for Asbestos and Environmental Claims, Net [Roll Forward]
Balance, Beginning	954.3	1,042.8
Changes in estimate during the period:
Continuing operations	(67.1)	(68.8)
Asbestos remeasurement	(66.4)	(75.9)
Settlement Agreement	0.0
Change in Defense Cost Estimate for Asbestos Matters	0.0	4.9
Net cash activity	(77.8)	(76.5)
Balance, Ending	877.2	954.3
Noncurrent portion		877.5
Asbestos Related Matters [Member] | Asset [Member]
Liability for Asbestos and Environmental Claims, Net [Roll Forward]
Balance, Beginning	380.6	412.0
Changes in estimate during the period:
Continuing operations	10.6	9.8
Asbestos remeasurement	(10.0)	(5.9)
Settlement Agreement	0.0	2.1
Change in Defense Cost Estimate for Asbestos Matters	0.0	0.0
Net cash activity	32.5	45.0
Balance, Ending	$ 368.7	$ 380.6