Benefit Plans - Pension Assets by Percentage (Details) - Pension Plan [Member]	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019
Asset category [Abstract]
Total plan assets (as a percent)	100.00%	100.00%
Expected long-term rate of return on plan assets	4.69%	3.84%
Fixed Income Funds [Member]
Asset category [Abstract]
Total plan assets (as a percent)	0.00%	55.00%
Equity Securities [Member]
Asset category [Abstract]
Total plan assets (as a percent)	66.00%	25.00%
Multi-Asset [Member]
Asset category [Abstract]
Total plan assets (as a percent)	24.00%	9.00%
Cash and Cash Equivalents [Member]
Asset category [Abstract]
Total plan assets (as a percent)	1.00%	7.00%
Alternative Investments [Member]
Asset category [Abstract]
Total plan assets (as a percent)	9.00%	4.00%
Maximum [Member] | Equity Securities [Member]
Asset category [Abstract]
Total plan assets (as a percent)	70.00%
Maximum [Member] | Alternative Investments [Member]
Asset category [Abstract]
Total plan assets (as a percent)	10.00%