Employee Benefit Plans - Schedule of Weighted-Average Assumptions Used (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 30, 2016
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit Cost for Current Plan Year (as a percent)			6.75%	7.00%
Benefit Cost for Subsequent Plan Year (as a percent)		6.75%	6.75%	6.75%
Benefit Cost for Plan Year (as a percent)			0.00%	0.00%
Service Cost for Plan Year (as a percent)	4.35%	4.26%	4.26%	4.30%
Interest Cost for Plan Year (as a percent)	3.37%	3.26%	3.26%	4.30%
Benefit Obligation at End of Plan Year (as a percent)		3.56%	3.56%	4.08%
Salary Scale Inflation (as a percent)			4.60%	4.60%
Post-retirement Medical Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit Cost for Plan Year (as a percent)			0.00%	0.00%
Service Cost for Plan Year (as a percent)	4.20%	4.11%	4.11%	3.85%
Interest Cost for Plan Year (as a percent)	2.88%	2.78%	2.78%	3.85%
Benefit Obligation at End of Plan Year (as a percent)		3.34%	3.34%	3.71%