Supplemental Guarantor Information - Condensed Consolidating Statement of Operations and Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions		3 Months Ended										12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018		Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net sales	[1]											$ 2,957.2	$ 2,965.1	$ 2,845.7
Cost of goods sold												1,905.7	1,917.4	1,858.2
Gross profit		$ 274.2	$ 255.0	$ 286.7	$ 235.6	$ 268.0		$ 243.8	$ 282.6		$ 253.3	1,051.5	1,047.7	987.5
Selling, general and administrative												540.1	534.3	536.0
Research and development												78.9	76.7	73.2
Operating income		122.3	108.8	133.8	67.6	113.0		108.4	122.6		92.7	432.5	436.7	378.3
Loss (earnings) from investment in subsidiaries												0.0	0.0	0.0
Other (income) expense:
(Gain) loss on sale of businesses												(2.2)	7.3	4.2
Loss on early extinguishment of debt												0.0	17.1	101.4
Net interest expense												30.1	32.6	87.3
Other (income) expense												(2.9)	(0.1)	12.6
Income from continuing operations before income taxes												407.5	379.8	172.8
Provision for income taxes												45.8	58.1	58.7
Net income from continuing operations		102.9	91.3	115.1	52.4	94.2	[2]	91.2	77.9	[3]	58.4	361.7	321.7	114.1
(Loss) income from discontinued operations, net of tax		(5.1)	1.0	(0.8)	(1.1)	(1.3)		18.9	(36.4)		44.5	(6.0)	25.7	371.3
Gain from sale of discontinued operations, net of tax												0.0	0.0	181.1
Earnings (loss) from discontinued operations of investment in subsidiaries												0.0	0.0	0.0
Net income		$ 97.8	$ 92.3	$ 114.3	$ 51.3	$ 92.9		$ 110.1	$ 41.5		$ 102.9	355.7	347.4	666.5
Net income (loss) from continuing operations before noncontrolling interest												355.7	347.4	666.5
Comprehensive income, net of tax
Changes in cumulative translation adjustment (inclusive of divestiture of business reclassified to gain from sale of $374.2 for the year ended December 31, 2017)												(15.3)	10.0	497.5
Changes in market value of derivative financial instruments												17.4	4.8	(4.6)
Comprehensive income												357.8	362.2	1,159.4
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales												0.0	0.0	0.0
Cost of goods sold												0.0	0.0	0.0
Gross profit												0.0	0.0	0.0
Selling, general and administrative												0.0	0.0	0.0
Research and development												0.0	0.0	0.0
Operating income												0.0	0.0	0.0
Loss (earnings) from investment in subsidiaries												1,132.7	1,043.4	527.8
Other (income) expense:
(Gain) loss on sale of businesses												0.0	0.0	0.0
Loss on early extinguishment of debt													0.0	0.0
Net interest expense												0.0	0.0	0.0
Other (income) expense												0.0	0.0	0.0
Income from continuing operations before income taxes												(1,132.7)	(1,043.4)	(527.8)
Provision for income taxes												0.0	0.0	0.0
Net income from continuing operations												(1,132.7)	(1,043.4)	(527.8)
(Loss) income from discontinued operations, net of tax												0.0	0.0	0.0
Gain from sale of discontinued operations, net of tax														0.0
Earnings (loss) from discontinued operations of investment in subsidiaries												18.0	(77.1)	(1,657.2)
Net income												(1,114.7)	(1,120.5)	(2,185.0)
Net income (loss) from continuing operations before noncontrolling interest												(1,114.7)	(1,120.5)	(2,185.0)
Comprehensive income, net of tax
Changes in cumulative translation adjustment (inclusive of divestiture of business reclassified to gain from sale of $374.2 for the year ended December 31, 2017)												45.9	(30.0)	(1,492.5)
Changes in market value of derivative financial instruments												(52.2)	(14.4)	13.8
Comprehensive income												(1,121.0)	(1,164.9)	(3,663.7)
Parent Company Guarantor
Condensed Financial Statements, Captions [Line Items]
Net sales												0.0	0.0	0.0
Cost of goods sold												0.0	0.0	0.0
Gross profit												0.0	0.0	0.0
Selling, general and administrative												12.5	11.8	9.0
Research and development												0.0	0.0	0.0
Operating income												(12.5)	(11.8)	(9.0)
Loss (earnings) from investment in subsidiaries												(374.2)	(333.5)	(122.2)
Other (income) expense:
(Gain) loss on sale of businesses												0.0	0.0	0.0
Loss on early extinguishment of debt													0.0	0.0
Net interest expense												0.0	0.0	0.0
Other (income) expense												0.0	0.0	0.0
Income from continuing operations before income taxes												361.7	321.7	113.2
Provision for income taxes												0.0	0.0	(0.9)
Net income from continuing operations												361.7	321.7	114.1
(Loss) income from discontinued operations, net of tax												0.0	0.0	0.0
Gain from sale of discontinued operations, net of tax														0.0
Earnings (loss) from discontinued operations of investment in subsidiaries												(6.0)	25.7	552.4
Net income												355.7	347.4	666.5
Net income (loss) from continuing operations before noncontrolling interest												355.7	347.4	666.5
Comprehensive income, net of tax
Changes in cumulative translation adjustment (inclusive of divestiture of business reclassified to gain from sale of $374.2 for the year ended December 31, 2017)												(15.3)	10.0	497.5
Changes in market value of derivative financial instruments												17.4	4.8	(4.6)
Comprehensive income												357.8	362.2	1,159.4
Subsidiary Guarantor
Condensed Financial Statements, Captions [Line Items]
Net sales												0.0	0.0	0.0
Cost of goods sold												0.0	0.0	0.0
Gross profit												0.0	0.0	0.0
Selling, general and administrative												0.1	0.9	0.6
Research and development												0.0	0.0	0.0
Operating income												(0.1)	(0.9)	(0.6)
Loss (earnings) from investment in subsidiaries												(376.3)	(333.4)	(122.2)
Other (income) expense:
(Gain) loss on sale of businesses												0.0	0.0	0.0
Loss on early extinguishment of debt													0.0	0.0
Net interest expense												2.0	(1.0)	(0.6)
Other (income) expense												0.0	0.0	0.0
Income from continuing operations before income taxes												374.2	333.5	122.2
Provision for income taxes												0.0	0.0	0.0
Net income from continuing operations												374.2	333.5	122.2
(Loss) income from discontinued operations, net of tax												0.0	0.0	0.0
Gain from sale of discontinued operations, net of tax														0.0
Earnings (loss) from discontinued operations of investment in subsidiaries												(6.0)	25.7	552.4
Net income												368.2	359.2	674.6
Net income (loss) from continuing operations before noncontrolling interest												368.2	359.2	674.6
Comprehensive income, net of tax
Changes in cumulative translation adjustment (inclusive of divestiture of business reclassified to gain from sale of $374.2 for the year ended December 31, 2017)												(15.3)	10.0	497.5
Changes in market value of derivative financial instruments												17.4	4.8	(4.6)
Comprehensive income												370.3	374.0	1,167.5
Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Net sales												0.0	0.0	0.0
Cost of goods sold												0.0	0.0	0.0
Gross profit												0.0	0.0	0.0
Selling, general and administrative												1.3	1.2	0.0
Research and development												0.0	0.0	0.0
Operating income												(1.3)	(1.2)	0.0
Loss (earnings) from investment in subsidiaries												(382.2)	(376.5)	(283.4)
Other (income) expense:
(Gain) loss on sale of businesses												0.0	0.0	0.0
Loss on early extinguishment of debt													17.1	91.0
Net interest expense												4.6	24.8	70.7
Other (income) expense												0.0	0.0	0.0
Income from continuing operations before income taxes												376.3	333.4	121.7
Provision for income taxes												0.0	0.0	0.0
Net income from continuing operations												376.3	333.4	121.7
(Loss) income from discontinued operations, net of tax												0.0	0.0	0.0
Gain from sale of discontinued operations, net of tax														0.0
Earnings (loss) from discontinued operations of investment in subsidiaries												(6.0)	25.7	552.4
Net income												370.3	359.1	674.1
Net income (loss) from continuing operations before noncontrolling interest												370.3	359.1	674.1
Comprehensive income, net of tax
Changes in cumulative translation adjustment (inclusive of divestiture of business reclassified to gain from sale of $374.2 for the year ended December 31, 2017)												(15.3)	10.0	497.5
Changes in market value of derivative financial instruments												17.4	4.8	(4.6)
Comprehensive income												372.4	373.9	1,167.0
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales												2,957.2	2,965.1	2,845.7
Cost of goods sold												1,905.7	1,917.4	1,858.2
Gross profit												1,051.5	1,047.7	987.5
Selling, general and administrative												526.2	520.4	526.4
Research and development												78.9	76.7	73.2
Operating income												446.4	450.6	387.9
Loss (earnings) from investment in subsidiaries												0.0	0.0	0.0
Other (income) expense:
(Gain) loss on sale of businesses												(2.2)	7.3	4.2
Loss on early extinguishment of debt													0.0	10.4
Net interest expense												23.5	8.8	17.2
Other (income) expense												(2.9)	(0.1)	12.6
Income from continuing operations before income taxes												428.0	434.6	343.5
Provision for income taxes												45.8	58.1	59.6
Net income from continuing operations												382.2	376.5	283.9
(Loss) income from discontinued operations, net of tax												(6.0)	25.7	371.3
Gain from sale of discontinued operations, net of tax														181.1
Earnings (loss) from discontinued operations of investment in subsidiaries												0.0	0.0	0.0
Net income												376.2	402.2	836.3
Net income (loss) from continuing operations before noncontrolling interest												376.2	402.2	836.3
Comprehensive income, net of tax
Changes in cumulative translation adjustment (inclusive of divestiture of business reclassified to gain from sale of $374.2 for the year ended December 31, 2017)												(15.3)	10.0	497.5
Changes in market value of derivative financial instruments												17.4	4.8	(4.6)
Comprehensive income												$ 378.3	$ 417.0	$ 1,329.2

[1] ⁽¹⁾  One customer in the Aquatic Systems segment, Pool Corporation, represented approximately 15% of our consolidated net sales in 2019, 2018 and 2017.

[2] ⁽²⁾  Amounts may not total to annual earnings because each quarter and year are calculated separately based on basic and diluted weighted-average ordinary shares outstanding during that period.

[3] ⁽¹⁾  Includes decrease of $17.1 million related to loss on early extinguishment of debt.