Basis of Presentation and Summary of Significant Accounting Policies (Changes in Estimates on Contracts) (Details) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jul. 03, 2026 |
Jul. 04, 2025 |
Jul. 03, 2026 |
Jul. 04, 2025 |
|
| Accounting Policies [Abstract] | ||||
| Favorable impact | $ 46 | $ 42 | $ 83 | $ 95 |
| Unfavorable impact | (20) | (34) | (66) | (57) |
| Net impact to income before income taxes | $ 26 | $ 8 | $ 17 | $ 38 |
| Impact on diluted EPS attributable to Leidos common stockholders (in dollars per share) | $ 0.15 | $ 0.05 | $ 0.10 | $ 0.22 |