Segments - Net Sales by Main Product Lines (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2022	Jan. 31, 2022	Oct. 31, 2021	Jul. 31, 2021	Apr. 30, 2021	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020
Revenue from External Customer [Line Items]
Total net sales	$ 1,288,653	$ 1,153,595	$ 1,150,551	$ 1,042,076	$ 932,203	$ 751,191	$ 812,856	$ 802,573	$ 4,634,875	$ 3,298,823	$ 3,241,307
Wallboard
Revenue from External Customer [Line Items]
Total net sales									1,710,851	1,346,648	1,329,775
Ceilings
Revenue from External Customer [Line Items]
Total net sales									567,700	451,766	475,827
Steel framing
Revenue from External Customer [Line Items]
Total net sales									1,027,941	469,048	502,122
Complementary products
Revenue from External Customer [Line Items]
Total net sales									$ 1,328,383	$ 1,031,361	$ 933,583