Net Sales - Summary of Net Sales by Product Line and Geography (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Disaggregation Of Revenue [Line Items]
Net sales	$ 1,754.9	$ 1,875.4	$ 1,872.1	$ 1,318.0	$ 1,576.5
Residential Roofing Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	919.8				844.8
Non-Residential Roofing Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	449.4				398.3
Complementary Building Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	385.7				333.4
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Net sales	1,701.5				1,528.4
U.S. [Member] | Residential Roofing Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	904.3				831.3
U.S. [Member] | Non-Residential Roofing Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	413.9				366.1
U.S. [Member] | Complementary Building Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	383.3				331.0
Canada [Member]
Disaggregation Of Revenue [Line Items]
Net sales	53.4				48.1
Canada [Member] | Residential Roofing Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	15.5				13.5
Canada [Member] | Non-Residential Roofing Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	35.5				32.2
Canada [Member] | Complementary Building Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 2.4				$ 2.4