v3.26.1
Revisions in Estimates - Summary of Impact of Revisions in Estimates to Gross Profit (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
project
$ / shares
Jun. 30, 2025
USD ($)
project
$ / shares
Jun. 30, 2026
USD ($)
project
$ / shares
Jun. 30, 2025
USD ($)
project
$ / shares
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net $ 238,771 $ 199,099 $ 348,676 $ 282,948
Change to project profitability, net (239,336) 107,559 (287,844) 67,476
Changes to net income (loss) (271,584) 80,345 (307,973) 52,018
Changes to net income (loss) attributable to Granite Construction Incorporated $ (278,162) $ 71,700 $ (319,861) $ 38,044
Increase to net income/decrease to net loss per diluted share attributable to common shareholders (in dollars per share) | $ / shares $ (6.36) $ 1.42 $ (7.33) $ 0.84
Revisions in Estimates        
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net     $ 5,000  
Revisions in Estimates, Increase        
Change in Accounting Estimate [Line Items]        
Number of projects with estimate changes 3 1 4 3
Range of change in gross profit from each project, net   $ 6,800    
Change to project profitability, net $ 24,700 6,800 $ 30,900 $ 22,900
Changes to net income (loss) 18,300 5,100 22,900 17,100
Income (Loss) Attributable to Noncontrolling Interest, before Tax 0 0 2,500 0
Changes to net income (loss) attributable to Granite Construction Incorporated $ 18,300 $ 5,100 $ 20,300 $ 17,100
Increase to net income/decrease to net loss per diluted share attributable to common shareholders (in dollars per share) | $ / shares $ 0.42 $ 0.10 $ 0.47 $ 0.33
Revisions in Estimates, Increase | Minimum        
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net $ 5,600   $ 5,600 $ 6,300
Revisions in Estimates, Increase | Maximum        
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net $ 11,400   $ 11,400 $ 9,800
Revisions in Estimates, Decrease        
Change in Accounting Estimate [Line Items]        
Number of projects with estimate changes | project 1 1 1 2
Range of change in gross profit from each project, net $ 10,700 $ 5,400 $ 14,200  
Change to project profitability, net 10,700 5,400 14,200 $ 21,100
Changes to net income (loss) attributable to Granite Construction Incorporated $ 8,000 $ 4,100 $ 10,500 $ 15,800
Increase to net income/decrease to net loss per diluted share attributable to common shareholders (in dollars per share) | $ / shares $ 0.18 $ 0.08 $ 0.24 $ 0.30
Revisions in Estimates, Decrease | Minimum        
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net       $ 6,800
Revisions in Estimates, Decrease | Maximum        
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net       $ 14,300