Other Postretirement Benefits - Changes in the Benefit Obligation and Plan Assets and Other Amounts (Details) - Other Postretirement Benefit Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2019	Dec. 30, 2018	Dec. 31, 2017
Change in benefit obligation
Benefit obligation at beginning of year	$ 46,037	$ 54,642
Service cost	27	21	$ 367
Interest cost	1,602	1,476	1,881
Plan participants’ contributions	3,835	3,974
Actuarial loss/(gain)	296	(4,905)
Benefits paid	(8,994)	(9,171)
Benefit obligation at end of year	42,803	46,037	$ 54,642
Change in plan assets
Fair value of plan assets at beginning of year	0
Employer contributions	5,159	5,197
Plan participants’ contributions	3,835	3,974
Benefits paid	(8,994)	(9,171)
Fair value of plan assets at end of year	0	0
Amount recognized in the Consolidated Balance Sheets
Current liabilities	(5,115)	(5,645)
Noncurrent liabilities	(37,688)	(40,392)
Net amount recognized	(42,803)	(46,037)
Amount recognized in accumulated other comprehensive loss
Actuarial loss	25,793	28,871
Prior service credit	(7,691)	(12,456)
Total	$ 18,102	$ 16,415