RESTRUCTURING-RELATED ACTIVITIES - Estimated Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 30, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 7,701
Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring costs	4,523
Inventory impairments
Restructuring Cost and Reserve [Line Items]
Restructuring costs	472
Asset impairments
Restructuring Cost and Reserve [Line Items]
Restructuring costs	573
Other Charges
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2,133
40 North Foods
Restructuring Cost and Reserve [Line Items]
Restructuring costs	702	$ 700
40 North Foods | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring costs	449
40 North Foods | Inventory impairments
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0
40 North Foods | Asset impairments
Restructuring Cost and Reserve [Line Items]
Restructuring costs	103
40 North Foods | Other Charges
Restructuring Cost and Reserve [Line Items]
Restructuring costs	150
GNP
Restructuring Cost and Reserve [Line Items]
Restructuring costs	6,999		$ 7,000
GNP | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring costs	4,074
GNP | Inventory impairments
Restructuring Cost and Reserve [Line Items]
Restructuring costs	472
GNP | Asset impairments
Restructuring Cost and Reserve [Line Items]
Restructuring costs	470
GNP | Other Charges
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1,983