Pretax Net Periodic Benefit Costs (Detail) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 25, 2017 |
Jun. 26, 2016 |
Jun. 25, 2017 |
Jun. 26, 2016 |
|
| Qualified defined benefit pension plans | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | $ 205 | $ 204 | $ 410 | $ 407 |
| Interest cost | 453 | 466 | 905 | 931 |
| Expected return on plan assets | (602) | (666) | (1,204) | (1,333) |
| Recognized net actuarial losses | 377 | 339 | 753 | 679 |
| Amortization of prior service costs | (90) | (92) | (176) | (182) |
| Total net periodic benefit cost | 343 | 251 | 688 | 502 |
| Retiree medical and life insurance plans | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | 5 | 6 | 10 | 12 |
| Interest cost | 25 | 29 | 51 | 59 |
| Expected return on plan assets | (32) | (35) | (64) | (69) |
| Recognized net actuarial losses | 5 | 9 | 10 | 17 |
| Amortization of prior service costs | 4 | 6 | 7 | 11 |
| Total net periodic benefit cost | $ 7 | $ 15 | $ 14 | $ 30 |