PENSION AND OTHER POSTRETIREMENT BENEFITS (Tables)

12 Months Ended

Dec. 31, 2017

Defined Benefit Plan [Abstract]

Schedule of Defined Benefit Plan Obligations and Assets

The change in benefit obligation, change in fair value of plan assets, funded status and amounts recognized in the Consolidated and Combined Balance Sheets for these plans were as follows:

	Pension Benefits						Other Benefits
	2017			2016			2017			2016
Change in projected benefit obligation:	(In thousands)
Projected benefit obligation, beginning of year	$	167,159		$	165,952		$	1,648		$	1,672
Interest cost	5,571			5,585			51			51
Actuarial losses (gains)	15,745			10,305			68			46
Benefits paid	(10,228		)	(6,098		)	—			—
Settlements(a)	—			(8,585		)	(164		)	(121		)
Projected benefit obligation, end of year	$	178,247		$	167,159		$	1,603		$	1,648

(a) A settlement is a transaction that is an irrevocable action, relieves the employer or the plan of primary responsibility for a pension or postretirement obligation and eliminates significant risks related to the obligation and the assets used to affect the settlement. A settlement can be triggered when a plan pays lump sums totaling more than the sum of the plan’s interest cost and service cost. The GK Pension Plan, the Retiree Life Plan, and the Union Pension Plan met this threshold in 2017 and 2016.

	Pension Benefits						Other Benefits
	2017			2016			2017			2016
Change in plan assets:	(In thousands)
Fair value of plan assets, beginning of year	$	97,526		$	96,947		$	—		$	—
Actual return on plan assets	12,325			4,460			—			—
Contributions by employer	12,947			10,802			164			121
Benefits paid	(10,228		)	(6,098		)	—			—
Settlements	—			(8,585		)	(164		)	(121		)
Fair value of plan assets, end of year	$	112,570		$	97,526		$	—		$	—

	Pension Benefits						Other Benefits
	2017			2016			2017			2016
Funded status:	(In thousands)
Unfunded benefit obligation, end of year	$	(65,677	)	$	(69,633	)	$	(1,603	)	$	(1,648	)

	Pension Benefits						Other Benefits
	2017			2016			2017			2016
Amounts recognized in the Consolidated and Combined Balance Sheets at end of year:	(In thousands)
Current liability	$	(12,168	)	$	(13,113	)	$	(149	)	$	(147	)
Long-term liability	(53,509		)	(56,520		)	(1,454		)	(1,501		)
Recognized liability	$	(65,677	)	$	(69,633	)	$	(1,603	)	$	(1,648	)

	Pension Benefits				Other Benefits
	2017		2016		2017		2016
Amounts recognized in accumulated other    comprehensive loss at end of year:	(In thousands)
Net actuarial loss (gain)	$	54,235	$	46,494	$	35	$	(31	)

Schedule of Net Periodic Benefit Cost (Income)

Net pension and other postretirement costs included the following components:

	Pension Benefits									Other Benefits
	2017			2016			2015			2017		2016			2015
	(In thousands)
Interest cost	$	5,571		$	5,585		$	7,754		$	51	$	51		$	67
Estimated return on plan assets	(5,254		)	(5,256		)	(6,684		)	—		—			—
Settlement loss (gain)	—			2,064			3,843			2		(2		)	(4		)
Amortization of net loss	932			659			714			—		—			—
Net cost	$	1,249		$	3,052		$	5,627		$	53	$	49		$	63

Schedule of Economic Assumptions, and Impact of Change in Discount Rate on Benefit Obligation

The sensitivity of the projected benefit obligation for pension benefits to changes in the discount rate is set out below. The impact of a change in the discount rate of 0.25% on the projected benefit obligation for other benefits is less than $1,000. This sensitivity analysis is based on changing one assumption while holding all other assumptions constant. In practice, this is unlikely to occur, and changes in some of the assumptions may be correlated. When calculating the sensitivity of the defined benefit obligation to variations in significant actuarial assumptions, the same method (present value of the defined benefit obligation calculated with the projected unit credit method at the end of the reporting period) has been applied as that for calculating the liability recognized in the Consolidated and Combined Balance Sheet.

	Increase in Discount Rate of 0.25%			Decrease in Discount Rate of 0.25%
	(In thousands)
Impact on projected benefit obligation for pension benefits	$	(5,087	)	$	4,828

The weighted average assumptions used in determining pension and other postretirement plan information were as follows:

	Pension Benefits						Other Benefits
	2017		2016		2015		2017		2016		2015
Benefit obligation:
Discount rate	3.69	%	4.31	%	4.47	%	3.39	%	3.81	%	4.47	%
Net pension and other postretirement cost:
Discount rate	4.32	%	4.47	%	4.22	%	3.81	%	4.47	%	4.22	%
Expected return on plan assets	5.50	%	5.50	%	5.50	%	NA		NA		NA

Schedule of Plan Asset Allocations

The following table reflects the pension plans’ actual asset allocations:

	2017		2016
Cash and cash equivalents	5	%	—	%
Pooled separate accounts(a):
Equity securities	5	%	5	%
Fixed income securities	4	%	5	%
Common collective trust funds(a):
Equity securities	56	%	60	%
Fixed income securities	30	%	30	%
Total assets	100	%	100	%

(a) Pooled separate accounts (“PSAs”) and common collective trust funds (“CCTs”) are two of the most common types of alternative vehicles in which benefit plans invest. These investments are pooled funds that look like mutual funds, but they are not registered with the Securities and Exchange Commission. Often times, they will be invested in mutual funds or other marketable securities, but the unit price generally will be different from the value of the underlying securities because the fund may also hold cash for liquidity purposes, and the fees imposed by the fund are deducted from the fund value rather than charged separately to investors. Some PSAs and CCTs have no restrictions as to their investment strategy and can invest in riskier investments, such as derivatives, hedge funds, private equity funds, or similar investments.

Schedule of Fair Value Assumptions of Plan Assets

The fair value measurements of plan assets fell into the following levels of the fair value hierarchy as of December 31, 2017 and December 25, 2016:

	2017								2016(a)
	Level 1(a)		Level 2(b)		Level 3(c)		Total		Level 1(a)		Level 2(b)		Level 3(c)		Total
	(In thousands)
Cash and cash equivalents	$	6,128	$	—	$	—	$	6,128	$	119	$	—	$	—	$	119
Pooled separate accounts:
Large U.S. equity funds(d)	—		3,483		—		3,483		—		3,302		—		3,302
Small/Mid U.S. equity funds(e)	—		420		—		420		—		406		—		406
International equity funds(f)	—		1,665		—		1,665		—		1,231		—		1,231
Fixed income funds(g)	—		4,799		—		4,799		—		4,867		—		4,867
Common collective trusts funds:
Large U.S. equity funds(d)	—		22,695		—		22,695		—		24,547		—		24,547
Small/Mid U.S. equity funds(e)	—		20,592		—		20,592		—		17,344		—		17,344
International equity funds(f)	—		19,923		—		19,923		—		17,006		—		17,006
Fixed income funds(g)	—		32,865		—		32,865		—		28,704		—		28,704
Total assets	$	6,128	$	106,442	$	—	$	112,570	$	119	$	97,407	$	—	$	97,526

(a) Unadjusted quoted prices in active markets for identical assets are used to determine fair value.

(b) Quoted prices in active markets for similar assets and inputs that are observable for the asset are used to determine fair value.

(c) Unobservable inputs, such as discounted cash flow models or valuations, are used to determine fair value.

(d) This category is comprised of investment options that invest in stocks, or shares of ownership, in large, well-established U.S. companies. These investment options typically carry more risk than fixed income options but have the potential for higher returns over longer time periods.

(e) This category is generally comprised of investment options that invest in stocks, or shares of ownership, in small to medium-sized U.S. companies. These investment options typically carry more risk than larger U.S. equity investment options but have the potential for higher returns.

(f) This category is comprised of investment options that invest in stocks, or shares of ownership, in companies with their principal place of business or office outside of the U.S.

(g) This category is comprised of investment options that invest in bonds, or debt of a company or government entity (including U.S. and non-U.S. entities). It may also include real estate investment options that directly own property. These investment options typically carry more risk than short-term fixed income investment options (including, for real estate investment options, liquidity risk), but less overall risk than equities.

Schedule of Benefit Payments

The following table reflects the benefits as of December 31, 2017 expected to be paid in each of the next five years and in the aggregate for the five years thereafter from our pension and other postretirement plans. Because our pension plans are primarily funded plans, the anticipated benefits with respect to these plans will come primarily from the trusts established for these plans. Because our other postretirement plans are unfunded, the anticipated benefits with respect to these plans will come from our own assets.

	Pension Benefits		Other Benefits
	(In thousands)
2018	$	18,368	$	148
2019	11,889		148
2020	11,687		146
2021	11,337		143
2022	11,160		139
2023-2027	50,628		611
Total	$	115,069	$	1,335

Schedule of Unrecognized Benefit Amounts

The amounts in accumulated other comprehensive income (loss) that were not recognized as components of net periodic benefits cost and the changes in those amounts are as follows:

	Pension Benefits									Other Benefits
	2017			2016			2015			2017			2016			2015
	(In thousands)
Net actuarial loss (gain), beginning of year	$	46,494		$	38,115		$	43,907		$	(31	)	$	(79	)	$	(127	)
Amortization	(932		)	(659		)	(714		)	—			—			—
Settlement adjustments	—			(2,064		)	(3,843		)	(2		)	2			4
Actuarial loss (gain)	15,745			10,305			(10,944		)	68			46			44
Asset loss (gain)	(7,072		)	797			9,709			—			—			—
Net actuarial loss (gain), end of year	$	54,235		$	46,494		$	38,115		$	35		$	(31	)	$	(79	)