Segments - Net Sales by Main Product Lines (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2025	Jan. 31, 2025	Oct. 31, 2024	Jul. 31, 2024	Apr. 30, 2024	Jan. 31, 2024	Oct. 31, 2023	Jul. 31, 2023	Apr. 30, 2025	Apr. 30, 2024	Apr. 30, 2023
Revenue from External Customer [Line Items]
Total net sales	$ 1,333,796	$ 1,260,710	$ 1,470,776	$ 1,448,456	$ 1,413,029	$ 1,258,348	$ 1,420,930	$ 1,409,600	$ 5,513,738	$ 5,501,907	$ 5,329,252
Wallboard
Revenue from External Customer [Line Items]
Total net sales									2,198,363	2,263,337	2,151,505
Complementary products
Revenue from External Customer [Line Items]
Total net sales									1,725,908	1,650,689	1,537,617
Steel framing
Revenue from External Customer [Line Items]
Total net sales									796,155	892,730	1,011,309
Ceilings
Revenue from External Customer [Line Items]
Total net sales									$ 793,312	$ 695,151	$ 628,821