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Acquisitions (Narrative) (Details) - USD ($) $ in Thousands					3 Months Ended
	Feb. 02, 2026	Jul. 31, 2025	Mar. 31, 2025	Feb. 11, 2025	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Sep. 30, 2025
Business Combination [Line Items]
Goodwill					$ 932,219		$ 415,032
Net sales					356,287	$ 246,357
Operating income (loss)					(4,456)	$ 28,655
Accrued expenses					8,900		$ 11,300
OmniMax
Business Combination [Line Items]
Payments to Acquire Businesses, Gross	$ 1,344,000
Goodwill	$ 519,029
Net sales					88,900
Operating income (loss)					$ (2,400)
Lane Supply
Business Combination [Line Items]
Goodwill				$ 38,281
Acquisition purchase price				$ 118,000
Two Privately Held Businesses
Business Combination [Line Items]
Acquisition purchase price			$ 92,600
Privately Held Business
Business Combination [Line Items]
Acquisition purchase price		$ 16,000
Increase in intangible assets								$ 20,200
Two Metal Roofing Businesses
Business Combination [Line Items]
Goodwill								$ 42,200
Metal Roofing Business
Business Combination [Line Items]
Goodwill		$ 8,800

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