Benefit Plans (Details) $ in Thousands	12 Months Ended
	Dec. 26, 2015 USD ($) Agreement		Dec. 27, 2014 USD ($)		Dec. 28, 2013 USD ($)
Change in fair value of plan assets [Roll Forward]
Actuarial net loss to be recognized as components of net periodic benefit cost in 2016	$ (3,100)
Defined benefit plan, amortization of prior service credit	$ (900)
Payable maximum period to be considered current	12 months
Funded status of the plans recognized [Abstract]
Long-term liability	$ (17,449)		$ (20,070)
Weighted average assumptions in net periodic benefit calculations [Abstract]
Minimum annual assumed rate of increase in the per capita cost of covered benefits	6.80%
Maximum annual assumed rate of increase in the per capita cost of covered benefits	9.00%
Ultimate health care cost trend rate	3.00%
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 176,077		$ 190,016
Approximate percentage of common stock invested in major industry	50.00%		51.00%
Approximate percentage of mutual funds actively managed	67.00%		40.00%
Approximate percentage of indexed mutual funds	33.00%		60.00%
Percentage of mutual funds' assets that are invested in U.S equities	12.00%		23.00%
Percent of mutual funds' assets that are invested in non-U.S. equities	38.00%		67.00%
Percent of mutual funds assets invested in US fixed income securities	46.00%
Percent of mutual funds' assets that are invested in non-U.S. fixed income securities	4.00%		10.00%
I.A.M Plan Trusts [Abstract]
Number of collective bargaining agreements | Agreement	2
Pension contributions under the I.A.M. pension plan trusts	$ 1,100		$ 1,000		$ 900
Minimum percentage of employer contributions	5.00%
Maximum percentage funded in the red zone, under the Pension Protection act of 2006	65.00%
Maximum percentage funded in the yellow zone, under the Pension Protection act of 2006	80.00%
Minimum percentage funded in the green zone, under the Pension Protection act of 2006	80.00%
401 (k) Plan [Abstract]
Compensation expense for the Company's matching contribution	$ 4,200		4,100		3,200
Contributions to UMWA 1992 Benefit Plan	214		249		290
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	51,527		121,879
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	119,960		63,067
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4,590		5,070
Cash and Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	16,632		84,377
Cash and Money Market Funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	16,632		84,377
Cash and Money Market Funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0		0
Cash and Money Market Funds [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0		0
Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	25,229	[1]	26,105	[2]
Common Stock [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	25,229	[1]	26,105	[2]
Common Stock [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	[1]	0	[2]
Common Stock [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	[1]	0	[2]
Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	129,626	[3]	74,464	[4]
Mutual Funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	9,666	[3]	11,397	[4]
Mutual Funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	119,960	[3]	63,067	[4]
Mutual Funds [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	[3]	0	[4]
Limited Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4,590		5,070
Limited Partnerships [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0		0
Limited Partnerships [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0		0
Limited Partnerships [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4,590		5,070
Limited Partnerships [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	5,070
Redemptions	(697)
Subscriptions	250
Net depreciation in fair value	(33)
Ending balance	4,590		5,070
Pension Benefits [Member]
Change in benefit obligation [Roll Forward]
Obligation at beginning of year	207,738		184,058
Service cost	803		973		948
Interest cost	8,032		8,590		7,774
Actuarial (gain) loss	(9,163)		30,138
Plan amendments	0		0
Business acquisitions	0		0
Benefit payments	(10,795)		(11,064)
Foreign currency translation adjustment	(3,854)		(4,957)
Obligation at end of year	192,761		207,738		184,058
Change in fair value of plan assets [Roll Forward]
Fair value of plan assets at beginning of year	190,016		188,870
Actual return on plan assets	(1,682)		12,716
Employer contributions	1,513		3,275
Benefit payments	(10,795)		(11,064)
Foreign currency translation adjustment	(2,975)		(3,781)
Fair value of plan assets at end of year	176,077		190,016		188,870
Underfunded funded status at end of year	(16,684)		(17,722)
Unrecognized net actuarial loss	48,681		49,830
Unrecognized prior service (credit) cost	0		0
Funded status of the plans recognized [Abstract]
Long-term asset	765		2,348
Current liability	0		0
Long-term liability	(17,449)		(20,070)
Total underfunded status	(16,684)		(17,722)
Components of net periodic benefit cost [Abstract]
Service cost	803		973		948
Interest cost	8,032		8,590		7,774
Expected return on plan assets	(10,289)		(13,669)		(11,059)
Amortization of prior service cost (credit)	0		1		1
Amortization of net (gain) loss	2,710		752		4,005
Net periodic benefit cost (income)	$ 1,256		$ (3,353)		$ 1,669
Weighted average assumptions in benefit obligations calculations [Abstract]
Discount rate	4.02%		4.03%
Expected long-term return on plan assets	5.59%		5.58%
Rate of inflation	3.20%		3.10%
Weighted average assumptions in net periodic benefit calculations [Abstract]
Discount rate	4.03%		4.82%		4.13%
Expected long-term return on plan assets	5.58%		7.40%		7.15%
Rate of inflation	3.10%		3.40%		2.70%
Asset category [Abstract]
Total plan assets	100.00%		100.00%
Expected long-term rate of return on plan assets	5.59%		5.58%
Future expected benefit payments [Abstract]
2016	$ 10,832
2017	10,856
2018	10,910
2019	10,994
2020	11,033
2021-2025	60,251
Total	114,876
Company's expected contribution to benefit plans in next fiscal year	$ 1,500
Pension Benefits [Member] | Equity Securities [Member]
Asset category [Abstract]
Total plan assets	51.00%		49.00%
Pension Benefits [Member] | Equity Securities [Member] | Maximum [Member]
Asset category [Abstract]
Total plan assets	30.00%
Pension Benefits [Member] | Fixed Income Securities [Member]
Asset category [Abstract]
Total plan assets	37.00%		4.00%
Pension Benefits [Member] | Fixed Income Securities [Member] | Minimum [Member]
Asset category [Abstract]
Total plan assets	60.00%
Pension Benefits [Member] | Cash and Money Market Funds [Member]
Asset category [Abstract]
Total plan assets	9.00%		44.00%
Pension Benefits [Member] | Alternative Investments [Member]
Asset category [Abstract]
Total plan assets	3.00%		3.00%
Pension Benefits [Member] | Alternative Investments [Member] | Maximum [Member]
Asset category [Abstract]
Total plan assets	5.00%
Other Benefits [Member]
Change in benefit obligation [Roll Forward]
Obligation at beginning of year	$ 19,307		$ 15,381
Service cost	363		348		$ 413
Interest cost	1,005		685		647
Actuarial (gain) loss	270		4,272
Plan amendments	(9,094)		0
Business acquisitions	5,655		0
Benefit payments	(1,037)		(1,142)
Foreign currency translation adjustment	(626)		(237)
Obligation at end of year	15,843		19,307		15,381
Change in fair value of plan assets [Roll Forward]
Fair value of plan assets at beginning of year	0		0
Actual return on plan assets	0		0
Employer contributions	1,037		1,142
Benefit payments	(1,037)		(1,142)
Foreign currency translation adjustment	0		0
Fair value of plan assets at end of year	0		0		0
Underfunded funded status at end of year	(15,843)		(19,307)
Unrecognized net actuarial loss	767		473
Unrecognized prior service (credit) cost	(9,087)		14
Funded status of the plans recognized [Abstract]
Long-term asset	0		0
Current liability	(1,221)		(1,251)
Long-term liability	(14,622)		(18,056)
Total underfunded status	(15,843)		(19,307)
Components of net periodic benefit cost [Abstract]
Service cost	363		348		413
Interest cost	1,005		685		647
Amortization of prior service cost (credit)	6		6		(2)
Amortization of net (gain) loss	(28)		(218)		(160)
Net periodic benefit cost (income)	$ 1,346		$ 821		$ 898
Weighted average assumptions in benefit obligations calculations [Abstract]
Discount rate	4.25%		4.33%
Rate of compensation increases	5.00%		5.00%
Weighted average assumptions in net periodic benefit calculations [Abstract]
Discount rate	4.33%		4.89%		4.06%
Rate of compensation increases	5.00%		5.50%		5.04%
Future expected benefit payments [Abstract]
2016	$ 1,221
2017	1,112
2018	1,147
2019	1,111
2020	1,356
2021-2025	5,973
Total	11,920
Company's expected contribution to benefit plans in next fiscal year	$ 1,200
U.K Plan [Member]
Change in fair value of plan assets [Roll Forward]
Percent of above benefit obligation on company sponsored UK pension plan	41.00%		40.00%
Percent above plan assets on company sponsored UK pension plan	35.00%		34.00%

[1] Approximately 50 percent of common stock represents investments in U.S. companies primarily in the health care, utilities, financials, consumer staples, industrials, and information technology sectors. All investments in common stock are listed on U.S. stock exchanges.

[2] Approximately 51 percent of common stock represents investments in U.S. companies primarily in the health care, utilities, financials, consumer staples, industrials, and information technology sectors. All investments in common stock are listed on U.S. stock exchanges.

[3] Approximately 67 percent of mutual funds are actively managed funds and approximately 33 percent of mutual funds are index funds. Additionally, 12 percent of the mutual funds' assets are invested in U.S. equities, 38 percent in non-U.S. equities, and 46 percent in U.S. fixed income securities, and 4 percent in non-U.S. fixed income securities.

[4] Approximately 40 percent of mutual funds are actively managed funds and approximately 60 percent of mutual funds are index funds. Additionally, 23 percent of the mutual funds' assets are invested in U.S. equities, 67 percent in non-U.S. equities, and 10 percent in non-U.S. fixed income securities.