v3.26.1
Segment Information - Schedule of Segment Reporting Information (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting Information [Line Items]        
Net sales $ 1,566 $ 814 $ 2,972 $ 1,580
Cost of sales 1,051 411 2,051 799
Selling, general and administrative 168 104 325 191
Engineering — research and development 56 43 110 85
Segment Operating Profit 328 288 559 559
Depreciation of property, plant and equipment     121 57
Amortization expense     44 3
Before Intersegment Eliminations        
Segment Reporting Information [Line Items]        
Net sales 1,569 814 2,978 1,580
Allison Transmission | Before Intersegment Eliminations        
Segment Reporting Information [Line Items]        
Net sales 860 814 1,593 1,580
Allison Off-Highway | Before Intersegment Eliminations        
Segment Reporting Information [Line Items]        
Net sales 709 0 1,385 0
Intersegment sales        
Segment Reporting Information [Line Items]        
Net sales 3 0 6 0
Intersegment sales | Allison Transmission        
Segment Reporting Information [Line Items]        
Net sales 0 0 0 0
Intersegment sales | Allison Off-Highway        
Segment Reporting Information [Line Items]        
Net sales 3 0 6 0
Operating Segments        
Segment Reporting Information [Line Items]        
Net sales 1,566 814 2,972 1,580
Segment Operating Profit     559  
Operating Segments | Allison Transmission        
Segment Reporting Information [Line Items]        
Net sales 860 814 1,593 1,580
Cost of sales 463 411 840 799
Selling, general and administrative 75 72 140 137
Engineering — research and development 41 43 80 85
Segment Operating Profit 281 288 533 559
Depreciation of property, plant and equipment 31 29 61 57
Amortization expense 0 1 1 3
Additions of long-lived assets 20 31 64 57
Operating Segments | Allison Off-Highway        
Segment Reporting Information [Line Items]        
Net sales 706 0 1,379 0
Cost of sales 588 0 1,211 0
Selling, general and administrative 56 0 112 0
Engineering — research and development 15 0 30 0
Segment Operating Profit 47 0 26 0
Depreciation of property, plant and equipment 33 0 60 0
Amortization expense 21 0 43 0
Additions of long-lived assets $ 11 $ 0 $ 20 $ 0