Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Change in fair value of plan assets:
Actuarial net loss	$ 1,500
Prior service credit	$ (900)
Payable maximum period to be considered current	12 months
Funded status of the plans recognized [Abstract]
Long-term liability	$ (11,606)	$ (14,890)
Weighted average assumptions in net periodic benefit calculations [Abstract]
Ultimate health care cost trend rate	3.00%
Minimum [Member]
Weighted average assumptions in net periodic benefit calculations [Abstract]
Annual assumed rate of increase in the per capita cost of covered benefits	6.60%
Maximum [Member]
Weighted average assumptions in net periodic benefit calculations [Abstract]
Annual assumed rate of increase in the per capita cost of covered benefits	10.10%
Pension Plan [Member]
Change in benefit obligation [Roll Forward]
Obligation at beginning of year	$ 178,736	192,761
Service cost	128	532	$ 803
Interest cost	6,344	7,553	8,032
Actuarial loss (gain)	4,688	9,399
Plan amendments	0	0
Benefit payments	(10,171)	(17,572)
Settlement charge	0	0
Foreign currency translation adjustment	7,041	(13,937)
Obligation at end of year	186,766	178,736	192,761
Change in fair value of plan assets:
Fair value of plan assets at beginning of year	169,140	176,077
Actual return on plan assets	19,175	19,319
Employer contributions	2,271	2,377
Benefit payments	(10,171)	(17,572)
Foreign currency translation adjustment	5,921	(11,061)
Fair value of plan assets at end of year	186,336	169,140	176,077
Underfunded status at end of year	(430)	(9,596)
Incremental benefit payments		7,000
Settlement charge	0	1,214	0
Unrecognized net actuarial loss	34,627	39,986
Unrecognized prior service credit	0	0
Funded status of the plans recognized [Abstract]
Long-term asset	9,894	4,442
Current liability	0	0
Long-term liability	(10,324)	(14,038)
Total underfunded status	(430)	(9,596)
Components of net periodic benefit cost [Abstract]
Service cost	128	532	803
Interest cost	6,344	7,553	8,032
Expected return on plan assets	(9,374)	(9,615)	(10,289)
Amortization of net (gain) loss	2,206	2,898	2,710
Settlement charge	0	1,214	0
Net periodic benefit (income) cost	$ (696)	$ 2,582	$ 1,256
Weighted average assumptions in benefit obligations calculations [Abstract]
Discount rate	3.22%	3.61%
Expected long-term return on plan assets	5.27%	5.56%
Rate of inflation	3.30%	3.30%
Weighted average assumptions in net periodic benefit calculations [Abstract]
Discount rate	3.61%	4.02%	4.03%
Expected long-term return on plan assets	5.56%	5.59%	5.58%
Rate of inflation	3.30%	3.20%	3.10%
Other Postretirement Benefit Plan [Member]
Change in benefit obligation [Roll Forward]
Obligation at beginning of year	$ 15,274	$ 15,843
Service cost	235	232	$ 363
Interest cost	599	594	1,005
Actuarial loss (gain)	923	(249)
Plan amendments	0	43
Benefit payments	(883)	(1,023)
Settlement charge	(209)	0
Foreign currency translation adjustment	468	(166)
Obligation at end of year	16,407	15,274	15,843
Change in fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	883	1,023
Benefit payments	(883)	(1,023)
Foreign currency translation adjustment	0	0
Fair value of plan assets at end of year	0	0	0
Underfunded status at end of year	(16,407)	(15,274)
Settlement charge	17	0	0
Unrecognized net actuarial loss	1,540	614
Unrecognized prior service credit	(7,289)	(8,180)
Funded status of the plans recognized [Abstract]
Long-term asset	0	0
Current liability	(1,070)	(1,128)
Long-term liability	(15,337)	(14,146)
Total underfunded status	(16,407)	(15,274)
Components of net periodic benefit cost [Abstract]
Service cost	235	232	363
Interest cost	599	594	1,005
Amortization of net (gain) loss	(42)	(60)	(28)
Amortization of prior service (credit) cost	(901)	(896)	6
Settlement charge	17	0	0
Net periodic benefit (income) cost	$ (92)	$ (130)	$ 1,346
Weighted average assumptions in benefit obligations calculations [Abstract]
Discount rate	3.89%	4.21%
Rate of compensation increases	5.00%	5.00%
Weighted average assumptions in net periodic benefit calculations [Abstract]
Discount rate	4.21%	4.25%	4.33%
Rate of compensation increases	5.00%	5.00%	5.00%
U.K Plan [Member]
Change in fair value of plan assets:
Percent of above benefit obligation on company sponsored UK pension plan	44.00%	42.00%
Percent above plan assets on company sponsored UK pension plan	39.00%	36.00%