RESTRUCTURING-RELATED ACTIVITIES - Restructuring Reserve (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 30, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Beginning liability or reserve	$ 236	$ 2,251
Restructuring charges incurred		692	$ 4,832
Restructuring income recognized	0
Payments and disposals	(34)	(2,707)	(2,581)
Ending liability or reserve	202	236	2,251
40 North Foods
Restructuring Cost and Reserve [Line Items]
Beginning liability or reserve	86	0
Restructuring charges incurred		564	0
Restructuring income recognized	(27)
Payments and disposals	(1)	(478)	0
Ending liability or reserve	58	86	0
40 North Foods | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Beginning liability or reserve	0	0
Restructuring charges incurred		449	0
Restructuring income recognized	0
Payments and disposals	0	(449)	0
Ending liability or reserve	0	0	0
40 North Foods | Other Charges
Restructuring Cost and Reserve [Line Items]
Beginning liability or reserve	86	0
Restructuring charges incurred		115	0
Restructuring income recognized	(27)
Payments and disposals	(1)	(29)	0
Ending liability or reserve	58	86	0
GNP | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Beginning liability or reserve	236	800
Restructuring charges incurred		936	3,381
Restructuring income recognized	0
Payments and disposals	(34)	(1,500)	(2,581)
Ending liability or reserve	202	236	800
GNP | Inventory impairments
Restructuring Cost and Reserve [Line Items]
Beginning liability or reserve	0	699
Restructuring charges incurred		(227)	699
Restructuring income recognized	0
Payments and disposals	0	(472)	0
Ending liability or reserve	0	0	699
GNP | Other Charges
Restructuring Cost and Reserve [Line Items]
Beginning liability or reserve	0	752
Restructuring charges incurred		(17)	752
Restructuring income recognized	0
Payments and disposals	0	(735)	0
Ending liability or reserve	$ 0	$ 0	$ 752