PENSION AND OTHER POSTRETIREMENT BENEFITS - Schedule of Fair Value Measurements of Plan Assets (Details) - USD ($) $ in Thousands	Mar. 27, 2022	Dec. 26, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	$ 306,641	$ 326,409
Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	35,288	6,166
Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	271,353	320,243
Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Cash and cash equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	35,288	6,166
Cash and cash equivalents | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	35,288	6,166
Cash and cash equivalents | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Cash and cash equivalents | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Large U.S. equity funds | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	2,385	2,595
Large U.S. equity funds | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	29,346	31,960
Large U.S. equity funds | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	34,788	45,373
Large U.S. equity funds | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	2,621
Large U.S. equity funds | Level 1 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Large U.S. equity funds | Level 1 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Large U.S. equity funds | Level 1 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Large U.S. equity funds | Level 1 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Large U.S. equity funds | Level 2 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	2,385	2,595
Large U.S. equity funds | Level 2 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	29,346	31,960
Large U.S. equity funds | Level 2 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	34,788	45,373
Large U.S. equity funds | Level 2 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	2,621
Large U.S. equity funds | Level 3 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Large U.S. equity funds | Level 3 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Large U.S. equity funds | Level 3 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Large U.S. equity funds | Level 3 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Small/Mid U.S. equity funds | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,254	1,338
Small/Mid U.S. equity funds | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	15,226	16,232
Small/Mid U.S. equity funds | Level 1 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Small/Mid U.S. equity funds | Level 1 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Small/Mid U.S. equity funds | Level 2 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,254	1,338
Small/Mid U.S. equity funds | Level 2 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	15,226	16,232
Small/Mid U.S. equity funds | Level 3 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Small/Mid U.S. equity funds | Level 3 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
International equity funds | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,800	1,954
International equity funds | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	14,711	15,710
International equity funds | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	27,059	60,188
International equity funds | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	8,606	11,696
International equity funds | Level 1 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 1 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 1 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 1 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 2 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,800	1,954
International equity funds | Level 2 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	14,711	15,710
International equity funds | Level 2 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	27,059	60,188
International equity funds | Level 2 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	8,606	11,696
International equity funds | Level 3 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 3 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 3 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
International equity funds | Level 3 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Fixed income funds | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	4,878	5,186
Fixed income funds | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	38,586	40,470
Fixed income funds | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,058	55,107
Fixed income funds | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	2,901	5,807
Fixed income funds | Level 1 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Fixed income funds | Level 1 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Fixed income funds | Level 1 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Fixed income funds | Level 1 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Fixed income funds | Level 2 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	4,878	5,186
Fixed income funds | Level 2 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	38,586	40,470
Fixed income funds | Level 2 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,058	55,107
Fixed income funds | Level 2 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	2,901	5,807
Fixed income funds | Level 3 | Union Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Fixed income funds | Level 3 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Fixed income funds | Level 3 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Fixed income funds | Level 3 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Liability driven investments | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	58,886	0
Liability driven investments | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	4,989	0
Liability driven investments | Level 1 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Liability driven investments | Level 1 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Liability driven investments | Level 2 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	58,886	0
Liability driven investments | Level 2 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	4,989	0
Liability driven investments | Level 3 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Liability driven investments | Level 3 | GEO Adams Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Real estate | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	5,759	5,405
Real estate | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	19,121	18,601
Real estate | Level 1 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Real estate | Level 1 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Real estate | Level 2 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	5,759	5,405
Real estate | Level 2 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	19,121	18,601
Real estate | Level 3 | GK Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
Real estate | Level 3 | U.K. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	$ 0	$ 0