Basis of Presentation and Summary of Significant Accounting Policies (Changes in Estimates on Contracts) (Details) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Oct. 03, 2025 |
Sep. 27, 2024 |
Oct. 03, 2025 |
Sep. 27, 2024 |
|
| Accounting Policies [Abstract] | ||||
| Favorable impact | $ 52 | $ 58 | $ 147 | $ 125 |
| Unfavorable impact | (32) | (28) | (89) | (107) |
| Net impact to income before income taxes | $ 20 | $ 30 | $ 58 | $ 18 |
| Impact on diluted EPS attributable to Leidos common stockholders (in dollars per share) | $ 0.11 | $ 0.17 | $ 0.34 | $ 0.10 |