v3.26.1
Schedule H, Line 4(i) - Schedule of Assets (Held At End of Year) (Details) - EBP 001
12 Months Ended
Dec. 31, 2025
USD ($)
EBP, Schedule of Asset Held for Investment [Line Items]  
Entity tax identification number 77-0239383
Plan number 001
Total Investments $ 959,201,696
Participant Loans $ 6,834,028
Minimum  
EBP, Schedule of Asset Held for Investment [Line Items]  
Investment rate 4.25%
Maximum  
EBP, Schedule of Asset Held for Investment [Line Items]  
Investment rate 9.50%
Total Investments at Fair Market Value  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments $ 952,367,668
Investment, Identifier [Axis]: AMERICAN FUNDS EUROPAC GRW R6, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 7,417,303
Investment, Identifier [Axis]: DODGE & COX INCOME I, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 12,529,522
Investment, Identifier [Axis]: FIDELITY INFL PROT BD IND, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 4,473,993
Investment, Identifier [Axis]: GRANITE CONSTRUCTION INC ESOP, Common Stock  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 46,254,242
Investment, Identifier [Axis]: GRANITE CONSTRUCTION INC STOCK, Common Stock  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 18,693,229
Investment, Identifier [Axis]: JP MORGAN LARGE CAP GROWTH R6, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 53,099,435
Investment, Identifier [Axis]: JP MORGAN MID CAP VALUE L, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 10,388,286
Investment, Identifier [Axis]: NORTHERN SMALL CAP VALUE FUND, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 5,198,207
Investment, Identifier [Axis]: T ROWE PRICE RET BLEND 2065 C Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 12,286,459
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2005 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 1,514,947
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2010 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 4,137,390
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2015 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 6,485,542
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2020 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 20,738,880
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2025 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 63,919,179
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2030 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 79,903,930
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2035 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 99,424,055
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2040 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 95,671,367
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2045 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 108,237,604
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2050 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 74,801,941
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2055 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 40,577,999
Investment, Identifier [Axis]: T ROWE Price RET BLEND 2060 C, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 27,109,064
Investment, Identifier [Axis]: TRP STABLE VALUE FUND - N, Common/Collective Trust  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 34,624,613
Investment, Identifier [Axis]: VANGUARD EQUITY INCOME ADM, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 15,438,125
Investment, Identifier [Axis]: VANGUARD EXPLORER, ADM, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 1,496,429
Investment, Identifier [Axis]: VANGUARD EXTENDED MKT INDEX, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 10,375,705
Investment, Identifier [Axis]: VANGUARD FED MONEY MARKET FUND, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 15,223,520
Investment, Identifier [Axis]: VANGUARD INST INDEX, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 59,464,095
Investment, Identifier [Axis]: VANGUARD TTL BND MRK INDX INST, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments 8,652,548
Investment, Identifier [Axis]: VANGUARD TTL INTL STK IDX INST, Mutual Fund  
EBP, Schedule of Asset Held for Investment [Line Items]  
Total Investments $ 14,230,059