Benefit Plans - Pension Assets by Percentage (Details) - Pension Plan [Member]	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016
Asset category [Abstract]
Total plan assets	100.00%	100.00%
Expected long-term rate of return on plan assets	5.27%	5.56%
Equity Securities [Member]
Asset category [Abstract]
Total plan assets	46.00%	47.00%
Fixed Income Funds [Member]
Asset category [Abstract]
Total plan assets	48.00%	48.00%
Cash and Cash Equivalents [Member]
Asset category [Abstract]
Total plan assets	3.00%	3.00%
Alternative Investments [Member]
Asset category [Abstract]
Total plan assets	3.00%	2.00%
Minimum [Member] | Fixed Income Funds [Member]
Asset category [Abstract]
Total plan assets	60.00%
Maximum [Member] | Equity Securities [Member]
Asset category [Abstract]
Total plan assets	30.00%
Maximum [Member] | Alternative Investments [Member]
Asset category [Abstract]
Total plan assets	5.00%