Restructuring - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) Person	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Person	Sep. 30, 2016 USD ($)	Dec. 31, 2016 Person
Restructuring Cost and Reserve [Line Items]
Number of employees | Person	400				650
Total restructuring costs	$ 4.9	$ 7.3	$ 38.6	$ 19.9
Water Unit [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees | Person			200		300
Total restructuring costs	1.4	0.2	$ 14.3	7.1
Electrical Unit [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees | Person			200		350
Total restructuring costs	1.7	7.1	$ 14.7	11.0
Corporate and Other [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	$ 1.8	$ 0.0	$ 9.6	$ 1.8