Fair Value Measurement - Significant Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total assets	$ 232,695	$ 73,031
Total liabilities	122	708
Heating oil swaps
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability	122
Interest rate swaps
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate swaps	830
Derivative liability		531
Diesel collars
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability		177
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total assets	231,865	73,031
Total liabilities	0	0
Level 1 \| Heating oil swaps
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability	0
Level 1 \| Interest rate swaps
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate swaps	0
Derivative liability		0
Level 1 \| Diesel collars
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability		0
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total assets	830	0
Total liabilities	122	708
Level 2 \| Heating oil swaps
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability	122
Level 2 \| Interest rate swaps
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate swaps	830
Derivative liability		531
Level 2 \| Diesel collars
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability		177
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total assets	0	0
Total liabilities	0	0
Level 3 \| Heating oil swaps
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability	0
Level 3 \| Interest rate swaps
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate swaps	0
Derivative liability		0
Level 3 \| Diesel collars
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability		0
Money market funds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash equivalents:	231,865	73,031
Money market funds \| Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash equivalents:	231,865	73,031
Money market funds \| Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash equivalents:	0	0
Money market funds \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Cash equivalents:	$ 0	$ 0

GRANITE CONSTRUCTION INC 10-K