Pension Plans and Postretirement Benefits (Narrative) (Details)	12 Months Ended
	Dec. 27, 2020	Dec. 29, 2019 USD ($)	Dec. 30, 2018 USD ($) participant	Dec. 31, 2017 USD ($)	Jan. 01, 2017 participant
Defined Benefit Plan Disclosure [Line Items]
Non-cash reduction to stockholders' equity		$ 323,100,000	$ 306,800,000
Deferred tax on non-cash reductions to stockholders' equity		102,500,000	96,900,000
Employer contributions to 401(k) plans		$ 13,400,000	11,900,000	$ 9,800,000
Assumed rate of increase in the per capita cost of covered benefits 2020		6.25%
Assumed rate of decrease in the per capita cost of covered benefits by 2027		5.00%
Effect of one percentage point increase in assumed health care cost trend rates on annual service and interest costs (less than)		$ 100,000
Effect of one percentage point increase in assumed health care cost trend rates on postretirement benefit obligation		200,000
Effect of one percentage point decrease in assumed health care cost trend rates on annual service and interest costs		100,000
Effect of one percentage point decrease in assumed health care cost trend rates on postretirement benefit obligation		200,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Annuity premium		0	$ 17,800,000	19,000,000.0
Number of plan participants | participant			321		412
Minimum liability adjustment to be recognized for the pension plans, net gain (loss)		22,900,000
Minimum liability adjustment to be recognized for the pension plans, net prior service credit		6,000,000.0
Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Minimum liability adjustment to be recognized for the pension plans, net gain (loss)		200,000
Service cost - benefits earned during the period (in millions)		0	$ 0	0
Unrecognized net gain		$ 2,200,000	2,500,000
United States | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of employees under defined benefit pension plan		10.00%
Settlements		$ 17,200,000	$ 18,600,000	$ 21,700,000
Expected long-term rate of return		7.80%	8.00%	8.00%
Service cost - benefits earned during the period (in millions)		$ 8,500,000	$ 9,800,000	$ 10,200,000
United States | Pension Benefits | Equity instruments
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets		52.00%
United States | Pension Benefits | Fixed income instruments
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets		34.00%
United States | Pension Benefits | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets		14.00%
Foreign Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period (in millions)		$ 900,000	$ 900,000	$ 1,000,000.0
Foreign Plan | Pension Benefits | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return		1.00%	1.00%	1.00%
Foreign Plan | Pension Benefits | Minimum | Scenario, Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return	1.00%
Foreign Plan | Pension Benefits | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return		3.80%	4.50%	5.90%
Foreign Plan | Pension Benefits | Maximum | Scenario, Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return	3.80%