v3.26.3
Revisions in Estimates - Summary of Impact of Revisions in Estimates to Gross Profit (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
USD ($)
project
$ / shares
Sep. 30, 2025
USD ($)
project
$ / shares
Sep. 30, 2026
USD ($)
project
$ / shares
Sep. 30, 2025
USD ($)
project
$ / shares
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net $ 335,760 $ 260,548 $ 684,436 $ 543,496
Change to project profitability, net 67,157 147,525 (220,687) 215,001
Changes to net income (loss) 10,391 109,397 (297,582) 161,415
Changes to net income (loss) attributable to Granite Construction Incorporated $ 3,210 $ 102,929 $ (316,651) $ 140,973
Increase to net income/decrease to net loss per diluted share attributable to common shareholders (in dollars per share) | $ / shares $ 0.07 $ 1.98 $ (7.23) $ 2.83
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 1 2 5 7
Change to project profitability, net $ 10,600 $ 13,300 $ 58,300 $ 50,800
Changes to net income (loss) 8,000 9,900 43,600 37,700
Income (Loss) Attributable to Noncontrolling Interest, before Tax 0 0 4,400 5,100
Changes to net income (loss) attributable to Granite Construction Incorporated $ 8,000 $ 9,900 $ 39,200 $ 32,600
Increase to net income/decrease to net loss per diluted share attributable to common shareholders (in dollars per share) | $ / shares $ 0.17 $ 0.18 $ 0.90 $ 0.62
Revisions in Estimates, Increase | Minimum        
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net     $ 7,900 $ 5,200
Change to project profitability, net   $ 5,000    
Revisions in Estimates, Increase | Maximum        
Change in Accounting Estimate [Line Items]        
Range of change in gross profit from each project, net     $ 18,200 $ 9,800
Change to project profitability, net   $ 8,300    
Revisions in Estimates, Decrease        
Change in Accounting Estimate [Line Items]        
Number of projects with estimate changes | project 0 1 1 3
Range of change in gross profit from each project, net $ 0 $ 5,900 $ 18,500  
Change to project profitability, net 0 5,900 18,500 $ 32,500
Changes to net income (loss) 0 4,400 13,800 24,100
Changes to net income (loss) attributable to Granite Construction Incorporated $ 0 $ 4,400 $ 13,800 $ 24,100
Increase to net income/decrease to net loss per diluted share attributable to common shareholders (in dollars per share) | $ / shares $ 0 $ 0.08 $ 0.32 $ 0.46
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       $ 15,100