PENSION AND OTHER POSTRETIREMENT BENEFITS - Schedule of Fair Value Measurements of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 26, 2021	Dec. 27, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	$ 326,409	$ 305,983
Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	6,166	1,487
Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	320,243	304,496
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	6,166	1,487
Cash and cash equivalents | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	6,166	1,487
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
PSAs for the Union Plan | Large U.S. equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	2,595	3,100
PSAs for the Union Plan | Large U.S. equity funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the Union Plan | Large U.S. equity funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	2,595	3,100
PSAs for the Union Plan | Large U.S. equity funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the Union Plan | Small/Mid U.S. equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,338	392
PSAs for the Union Plan | Small/Mid U.S. equity funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the Union Plan | Small/Mid U.S. equity funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,338	392
PSAs for the Union Plan | Small/Mid U.S. equity funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the Union Plan | International equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,954	1,874
PSAs for the Union Plan | International equity funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the Union Plan | International equity funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	1,954	1,874
PSAs for the Union Plan | International equity funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the Union Plan | Fixed income funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	5,186	5,365
PSAs for the Union Plan | Fixed income funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the Union Plan | Fixed income funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	5,186	5,365
PSAs for the Union Plan | Fixed income funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | Large U.S. equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	31,960	29,602
PSAs and CCTs for the GK Pension Plan | Large U.S. equity funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | Large U.S. equity funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	31,960	29,602
PSAs and CCTs for the GK Pension Plan | Large U.S. equity funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | Small/Mid U.S. equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	16,232	17,569
PSAs and CCTs for the GK Pension Plan | Small/Mid U.S. equity funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | Small/Mid U.S. equity funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	16,232	17,569
PSAs and CCTs for the GK Pension Plan | Small/Mid U.S. equity funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | International equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	15,710	16,320
PSAs and CCTs for the GK Pension Plan | International equity funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | International equity funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	15,710	16,320
PSAs and CCTs for the GK Pension Plan | International equity funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | Fixed income funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	40,470	38,944
PSAs and CCTs for the GK Pension Plan | Fixed income funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | Fixed income funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	40,470	38,944
PSAs and CCTs for the GK Pension Plan | Fixed income funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | Real estate
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	5,405	5,677
PSAs and CCTs for the GK Pension Plan | Real estate | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs and CCTs for the GK Pension Plan | Real estate | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	5,405	5,677
PSAs and CCTs for the GK Pension Plan | Real estate | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the U.K. Plans | Large U.S. equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	47,995	39,002
PSAs for the U.K. Plans | Large U.S. equity funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the U.K. Plans | Large U.S. equity funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	47,995	39,002
PSAs for the U.K. Plans | Large U.S. equity funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the U.K. Plans | International equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	71,883	69,251
PSAs for the U.K. Plans | International equity funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the U.K. Plans | International equity funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	71,883	69,251
PSAs for the U.K. Plans | International equity funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the U.K. Plans | Fixed income funds
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	60,914	60,212
PSAs for the U.K. Plans | Fixed income funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the U.K. Plans | Fixed income funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	60,914	60,212
PSAs for the U.K. Plans | Fixed income funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the U.K. Plans | Real estate
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	18,601	17,188
PSAs for the U.K. Plans | Real estate | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	0	0
PSAs for the U.K. Plans | Real estate | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	18,601	17,188
PSAs for the U.K. Plans | Real estate | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair value of plan assets	$ 0	$ 0