Pension, Postretirement and Postemployment Benefits, Beginning of Fair Value Measurement (Details) - USD ($) $ in Thousands	Dec. 25, 2016	Dec. 27, 2015
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	$ 309,300	$ 259,300
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	58,300	51,900
Significant Other Observable Inputs (Level 2) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Significant Unobservable Inputs (Level 3) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - Large Cap [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	29,100	27,600
Equity - Large Cap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	29,100	27,600
Equity - Large Cap [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - Large Cap [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - Small Cap [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	29,200	24,300
Equity - Small Cap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	29,200	24,300
Equity - Small Cap [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - Small Cap [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - International [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	40,100	37,500
Equity - International [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - International [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - International [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - Other [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	1,300	2,500
Equity - Other [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - Other [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Equity - Other [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Fixed Income Funds [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	119,500	122,600
Fixed Income Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Fixed Income Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Fixed Income Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Total Return Fund [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	29,000	27,700
Total Return Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Total Return Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Total Return Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Cash Equivalents [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	61,100	17,100
Cash Equivalents [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Cash Equivalents [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	0	0
Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair values of plan assets by asset class and fair value hierarchy level [Abstract]
Fair Value of Plan Asset	$ 0	$ 0