Investments in Affiliates - Summarized Balance Sheet Information for Equity Method Investments (Details) - USD ($) $ in Thousands |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Schedule of Equity Method Investments [Line Items] | ||
| Current assets | $ 2,122,716 | $ 1,812,231 |
| Total assets | 4,468,399 | 4,030,393 |
| Current liabilities | 1,905,853 | 1,481,745 |
| Granite’s share of net assets | 86,390 | 96,764 |
| Equity Method Investment, Nonconsolidated Investee or Group of Investees | ||
| Schedule of Equity Method Investments [Line Items] | ||
| Current assets | 209,717 | 215,601 |
| Noncurrent assets | 109,901 | 122,280 |
| Total assets | 319,618 | 337,881 |
| Current liabilities | 84,032 | 73,005 |
| Long-term liabilities | 43,436 | 51,087 |
| Total liabilities | 127,468 | 124,092 |
| Net assets | $ 192,150 | $ 213,789 |
| X | ||||||||||
- Definition Amount of asset recognized for present right to economic benefit. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of asset recognized for present right to economic benefit, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of net assets (liabilities). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of liability recognized for present obligation requiring transfer or otherwise providing economic benefit to others. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Total obligations incurred as part of normal operations that are expected to be paid during the following twelve months or within one business cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of obligation due after one year or beyond the normal operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Details
|