Supplemental Equity Information - Reclassifications out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 27, 2015	Sep. 30, 2016	Sep. 27, 2015
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, before tax	$ (22)	$ 76	$ 108	$ (1,160)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, before tax	1,785	3,742	5,977	35,150
Accumulated Defined Benefit Plans Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, before tax	1,763	3,818	6,085	33,990
Income tax effect	(688)	(1,508)	(2,368)	(12,375)
Total reclassifications, net of tax	$ 1,075	$ 2,310	$ 3,717	$ 21,615