Information on Business Segments - Net Sales and Operating Income by Segment (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net sales	$ 1,936.1	$ 1,375.8	$ 3,707.1	$ 2,778.5
Operating income	$ 294.9	173.0	$ 543.3	328.0
Net Sales, Percentage Change vs. Prior Year	40.70%		33.40%
Operating Income, Percentage Change vs. Prior Year	70.50%		65.60%
Corporate [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating income	$ (26.9)	(19.0)	$ (51.8)	(43.7)
Operating Income, Percentage Change vs. Prior Year	(41.60%)		(18.50%)
Plumbing [Member] \| Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net sales	$ 694.6	504.8	$ 1,316.2	973.8
Operating income	$ 168.9	109.5	$ 316.8	214.0
Net Sales, Percentage Change vs. Prior Year	37.60%		35.20%
Operating Income, Percentage Change vs. Prior Year	54.20%		48.00%
Outdoors & Security [Member] \| Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net sales	$ 535.5	332.3	$ 997.0	646.0
Operating income	$ 78.5	45.2	$ 131.3	76.7
Net Sales, Percentage Change vs. Prior Year	61.10%		54.30%
Operating Income, Percentage Change vs. Prior Year	73.70%		71.20%
Cabinets [Member] \| Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net sales	$ 706.0	538.7	$ 1,393.9	1,158.7
Operating income	$ 74.4	$ 37.3	$ 147.0	$ 81.0
Net Sales, Percentage Change vs. Prior Year	31.10%		20.30%
Operating Income, Percentage Change vs. Prior Year	99.50%		81.50%