Fair Value Measurements (Fair value measurements on a nonrecurring basis) (Details) - Fair value, measurements, nonrecurring [Member] - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 01, 2018	Jun. 25, 2017	Jul. 01, 2018	Jun. 25, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total impairment losses		$ 4,721	$ 12	$ 6,992	$ 932
Assets held for sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of long-lived assets to be disposed of		0	0	50	70
Property, plant and equipment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, fixtures and equipment, impairment		4,721	12	6,942	862
Reported value measurement [Member] | Fair value, inputs, level 2 [Member] | Assets measured with impairment, quarter-to-date [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	[1]	1,060	0	1,060	0
Reported value measurement [Member] | Fair value, inputs, level 2 [Member] | Assets measured with impairment, year-to-date [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	[1]	1,430	1,467	1,430	1,467
Reported value measurement [Member] | Assets held for sale [Member] | Fair value, inputs, level 2 [Member] | Assets measured with impairment, quarter-to-date [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	[1]	0	0	0	0
Reported value measurement [Member] | Assets held for sale [Member] | Fair value, inputs, level 2 [Member] | Assets measured with impairment, year-to-date [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	[1]	50	400	50	400
Reported value measurement [Member] | Property, plant and equipment [Member] | Fair value, inputs, level 2 [Member] | Assets measured with impairment, quarter-to-date [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	[1]	1,060	0	1,060	0
Reported value measurement [Member] | Property, plant and equipment [Member] | Fair value, inputs, level 2 [Member] | Assets measured with impairment, year-to-date [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	[1]	$ 1,380	$ 1,067	$ 1,380	$ 1,067

[1] Carrying value approximates fair value with all assets measured using third-party market appraisals or purchase contracts (Level 2).