Retirement Plans Assumptions to Determine Benefit Obligations at Period-end and Net Pension Costs (Details) |
12 Months Ended | ||
|---|---|---|---|
Dec. 28, 2019 |
Dec. 29, 2018 |
Dec. 30, 2017 |
|
| Pension Benefits | |||
| Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] | |||
| Benefit obligation, discount rate | 3.50% | 4.35% | 3.70% |
| Benefit obligation, annual compensation increase | 3.60% | 3.60% | 3.60% |
| Net cost, discount rate | 4.35% | 3.70% | 4.25% |
| Net cost, expected return on plan assets | 6.00% | 6.00% | 6.00% |
| Net cost, annual compensation increase | 3.60% | 3.60% | 3.60% |
| Other Postretirement Plans | |||
| Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] | |||
| Benefit obligation, discount rate | 3.50% | 4.35% | 3.70% |
| Net cost, discount rate | 4.35% | 3.70% | 4.25% |