Restructuring - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Person	Jun. 30, 2016 USD ($)	Dec. 31, 2016 Person
Restructuring Cost and Reserve [Line Items]
Number of employees | Person			300		650
Total restructuring costs	$ 12.8	$ 12.1	$ 33.7	$ 12.6
Water Unit [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees | Person			150		300
Total restructuring costs	5.8	7.5	$ 12.9	6.9
Electrical Unit [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees | Person			150		350
Total restructuring costs	3.7	3.7	$ 13.0	3.9
Corporate and Other [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	$ 3.3	$ 0.9	$ 7.8	$ 1.8