Pension, Postretirement and Postemployment Benefits, End of Fair Value Measurement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 25, 2016	Dec. 27, 2015
Equity - Other [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Investments for which the fair value is measured using net asset value per share	300
Fixed Income Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Investments for which the fair value is measured using net asset value per share	217,200
Cash Equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Investments for which the fair value is measured using net asset value per share	31,000
International Plans [Member]
Expected benefit payments under defined benefit pension plans and postretirement benefit plan for next five years [Abstract]
2018	$ 2,019
2019	2,179
2020	2,368
2021	2,524
2022	2,772
2023-2027	17,806
Projected benefit obligation	127,012	$ 118,492
Fair value of plan assets	100,766	$ 85,678
Expected amortization of unrecognized transition obligation in next fiscal year	$ 2
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Shared long-term total return goal on plan assets	6.25%	6.75%	7.00%
Components of net periodic cost [Abstract]
Service cost	$ 1,290	$ 2,100	$ 1,918
Interest cost	15,303	16,106	15,683
Expected return on assets	(19,534)	(17,013)	(18,538)
Amortization of prior service cost	0	0	65
Amortization of actuarial loss	9,082	7,361	7,468
Curtailment/settlement losses	0	0	781
Net periodic benefit cost	$ 6,141	$ 8,554	$ 7,377
Assumptions used to determine net periodic benefit cost of pension plan and postretirement plan [Abstract]
Weighted average discount rate	4.22%	4.58%	4.22%
Long-term rate of return on plan assets	6.25%	6.75%	7.00%
Expected benefit payments under defined benefit pension plans and postretirement benefit plan for next five years [Abstract]
2018	$ 20,803
2019	21,125
2020	21,315
2021	21,943
2022	22,391
2023-2027	117,813
Postretirement [Member]
Components of net periodic cost [Abstract]
Service cost	691	$ 532	$ 567
Interest cost	1,179	1,175	1,154
Amortization of actuarial loss	0	0	(304)
Curtailment/settlement losses	0	0	(3,842)
Net periodic benefit cost	$ 1,870	$ 1,707	$ (2,425)
Assumptions used to determine net periodic benefit cost of pension plan and postretirement plan [Abstract]
Weighted average discount rate	4.26%	4.64%	4.49%
Health care cost trend rate assumed for next year	7.00%	7.00%	6.50%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate)	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2021	2021	2020
Effect of one percentage point increase in health care cost trend rate on accumulated postretirement benefit obligation and aggregate of benefits earned and interest cost	0.60%
Expected benefit payments under defined benefit pension plans and postretirement benefit plan for next five years [Abstract]
2018	$ 1,660
2019	1,601
2020	1,552
2021	1,506
2022	1,467
2023-2027	$ 6,922