Goodwill and Other Identifiable Intangible Assets - Changes in Carrying Amount of Goodwill by Segment (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)
Goodwill [Roll Forward]
Beginning Balance	$ 4,217.4
Goodwill, Purchase Accounting Adjustments	33.0
Foreign currency translation/other	63.8
Ending Balance	4,314.2
Water Unit [Member]
Goodwill [Roll Forward]
Beginning Balance	1,994.6
Goodwill, Purchase Accounting Adjustments	27.7
Foreign currency translation/other	58.2
Ending Balance	2,080.5
Electrical Unit [Member]
Goodwill [Roll Forward]
Beginning Balance	2,222.8
Goodwill, Purchase Accounting Adjustments	5.3
Foreign currency translation/other	5.6
Ending Balance	$ 2,233.7