Acquisitions - Pro Forma Financial Information (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | |
|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
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| Kenny Seng Construction | |||
| Business Combination, Pro Forma Information [Line Items] | |||
| Revenue | $ 1,478,936 | $ 4,176,578 | $ 3,370,735 |
| Net income (loss) attributable to Granite Construction Incorporated | 104,549 | (323,880) | 141,514 |
| Warren Paving | |||
| Business Combination, Pro Forma Information [Line Items] | |||
| Revenue | 1,464,436 | 3,408,831 | |
| Net income (loss) attributable to Granite Construction Incorporated | 111,068 | $ 147,580 | |
| Papich Construction | |||
| Business Combination, Pro Forma Information [Line Items] | |||
| Revenue | 1,452,705 | 3,364,348 | |
| Net income (loss) attributable to Granite Construction Incorporated | $ 104,014 | $ 148,374 | |
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