Selected Quarterly Data (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Selected Quarterly Financial Information [Abstract]
Net sales	$ 796.0	$ 798.5	$ 713.3	$ 710.0	$ 755.2	$ 713.6	$ 799.5	$ 688.9	$ 3,017.8	[1]	$ 2,957.2	[1]	$ 2,965.1	[1]
Gross profit	283.5	277.4	245.1	251.6	274.2	255.0	286.7	235.6	1,057.6		1,051.5		1,047.7
Operating income	121.5	128.1	111.1	100.7	122.3	108.8	133.8	67.6	461.4		432.5		436.7
Net income from continuing operations	99.8	110.8	73.8	72.7	102.9	91.3	115.1	52.4	357.1		361.7		321.7
(Loss) income from discontinued operations, net of tax	3.2	0.0	(1.7)	0.0	(5.1)	1.0	(0.8)	(1.1)	1.5		(6.0)		25.7
Net income	$ 103.0	$ 110.8	$ 72.1	$ 72.7	$ 97.8	$ 92.3	$ 114.3	$ 51.3	$ 358.6		$ 355.7		$ 347.4
Earnings (loss) per ordinary share
Continuing operations (USD per share)	$ 0.60	$ 0.67	$ 0.44	$ 0.43	$ 0.61	$ 0.54	$ 0.68	$ 0.31	$ 2.14		$ 2.14		$ 1.83
Discontinued operations (USD per share)	0.02	0	(0.01)	0	(0.03)	0.01	(0.01)	(0.01)	0.01		(0.04)		0.15
Earnings Per Share, Basic (USD per share)	0.62	0.67	0.43	0.43	0.58	0.55	0.67	0.30	2.15		2.10		1.98
Continuing operations (USD per share)	0.60	0.66	0.44	0.43	0.61	0.54	0.68	0.30	2.13		2.12		1.81
Discontinued operations (USD per share)	0.01	0	(0.01)	0	(0.03)	0.01	(0.01)	0	0.01		(0.03)		0.15
Diluted earnings (loss) per common share (USD per share)	$ 0.61	$ 0.66	$ 0.43	$ 0.43	$ 0.58	$ 0.55	$ 0.67	$ 0.30	$ 2.14		$ 2.09		$ 1.96

[1] (1) One customer in the Consumer Solutions segment, Pool Corporation, represented approximately 15% of our consolidated net sales in 2020, 2019 and 2018.