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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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