EMPLOYEE BENEFITS - Fair value (Details) - Pension plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2019	Dec. 30, 2018	Dec. 31, 2017
EMPLOYEE BENEFITS
Fair value of plan assets	$ 1,393,267	$ 1,259,979	$ 1,477,926
Cash and cash equivalents
EMPLOYEE BENEFITS
Fair value of plan assets	9,355	9,366
Mutual funds
EMPLOYEE BENEFITS
Fair value of plan assets	139,021	139,978
Common collective trust
EMPLOYEE BENEFITS
Fair value of plan assets	1,178,230	1,045,628
U.S. equity funds
EMPLOYEE BENEFITS
Fair value of plan assets	$ 358,088	$ 296,135
Redemption notice period	0 days	0 days
International equity funds
EMPLOYEE BENEFITS
Fair value of plan assets	$ 373,764	$ 311,119
Redemption notice period	0 days	0 days
Emerging markets equity funds
EMPLOYEE BENEFITS
Fair value of plan assets	$ 179,707	$ 153,927
Fixed income funds
EMPLOYEE BENEFITS
Fair value of plan assets	$ 126,900	$ 146,197
Redemption notice period	2 days	2 days
Fixed income credit fund
EMPLOYEE BENEFITS
Fair value of plan assets	$ 139,771	$ 138,250
Redemption notice period	2 days	2 days
Total Common collective trust
EMPLOYEE BENEFITS
Fair value of plan assets	$ 1,038,459	$ 907,378
Real Estate
EMPLOYEE BENEFITS
Fair value of plan assets	55,874	55,398
Private Equity
EMPLOYEE BENEFITS
Fair value of plan assets	$ 10,787	$ 9,609
Minimum | Emerging markets equity funds
EMPLOYEE BENEFITS
Redemption notice period	0 days	0 days
Maximum | Emerging markets equity funds
EMPLOYEE BENEFITS
Redemption notice period	5 days	5 days
Level 1
EMPLOYEE BENEFITS
Fair value of plan assets	$ 148,376	$ 149,344
Level 1 | Cash and cash equivalents
EMPLOYEE BENEFITS
Fair value of plan assets	9,355	9,366
Level 1 | Mutual funds
EMPLOYEE BENEFITS
Fair value of plan assets	139,021	139,978
Level 3
EMPLOYEE BENEFITS
Fair value of plan assets	66,661	65,007	67,559
Level 3 | Real Estate
EMPLOYEE BENEFITS
Fair value of plan assets	55,874	55,398	58,050
Level 3 | Private Equity
EMPLOYEE BENEFITS
Fair value of plan assets	10,787	9,609	$ 9,509
NAV
EMPLOYEE BENEFITS
Fair value of plan assets	1,178,230	1,045,628
NAV | Common collective trust
EMPLOYEE BENEFITS
Fair value of plan assets	$ 1,178,230	$ 1,045,628