Acquisitions - Additional Information (Detail) - USD ($) $ in Millions			3 Months Ended		9 Months Ended
	Sep. 05, 2017	Aug. 08, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Aggregate cash purchase price, net of cash acquired					$ 43.1	$ 90.5
Operating earnings			$ 144.0	$ 131.6	422.2	$ 387.4
Aquasana
Business Acquisition [Line Items]
Percentage of ownership interest acquired		100.00%
Aggregate cash purchase price, net of cash acquired		$ 85.1
Cash acquired from business acquisition		1.9
Contingent consideration and holdback		1.7
Acquisition-related costs		1.2
Acquired intangible assets		30.0
Aquasana | Trade Names
Business Acquisition [Line Items]
Acquired intangible assets, not subject to amortization		21.5
Aquasana | Customer Lists
Business Acquisition [Line Items]
Acquired intangible assets, subject to amortization		$ 8.3
Acquired intangible assets, amortization period, in years		10 years
Aquasana | Patents
Business Acquisition [Line Items]
Acquired intangible assets, subject to amortization		$ 0.2
Acquired intangible assets, amortization period, in years		5 years
Hague
Business Acquisition [Line Items]
Percentage of ownership interest acquired	100.00%
Aggregate cash purchase price, net of cash acquired	$ 43.1
Cash acquired from business acquisition	4.1
Contingent consideration and holdback	$ 1.5		$ 2.0		$ 2.0
Contingent consideration, conditions measurement period	2 years
Acquisition-related costs	$ 0.1
Acquired intangible assets	12.8
Revenues	2.2
Pre tax earnings	0.6
Operating earnings	0.7
Hague | Maximum
Business Acquisition [Line Items]
Contingent consideration and holdback	2.0
Hague | Trade Names
Business Acquisition [Line Items]
Acquired intangible assets, not subject to amortization	1.1
Hague | Customer Lists
Business Acquisition [Line Items]
Acquired intangible assets, subject to amortization	$ 11.7
Acquired intangible assets, amortization period, in years	18 years