POSTRETIREMENT MEDICAL BENEFITS AND PENSION (Tables)

6 Months Ended

Jun. 30, 2018

Postretirement Medical Benefits

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Components of net periodic benefit cost

The components of net periodic postretirement medical benefit cost are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
	(In thousands)
Components of net periodic postretirement medical benefit cost:
Service cost	$	889	$	794	$	1,779	$	1,587
Interest cost	2,893		3,196		5,786		6,393
Amortization of deferred items	969		965		1,938		1,929
Total net periodic postretirement medical benefit cost	$	4,751	$	4,955	$	9,503	$	9,909

Service cost is included in Cost of sales (exclusive of depreciation, depletion and amortization, shown separately) in the Consolidated Statements of Operations (unaudited) and interest cost and amortization of deferred items are included in Other expense in the Consolidated Statements of Operations (unaudited).

The following table shows the net periodic postretirement medical benefit costs that relate to current and former mining operations:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
	(In thousands)
Former mining operations	$	2,046	$	2,306	$	4,092	$	4,611
Current operations	2,705		2,649		5,411		5,298
Total net periodic postretirement medical benefit cost	$	4,751	$	4,955	$	9,503	$	9,909

Pension

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Components of net periodic benefit cost

The components of net periodic pension benefit cost are as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
	(In thousands)
Components of net periodic pension benefit cost:
Service cost	$	410		$	378		$	821		$	785
Interest cost	2,387			2,630			4,777			5,260
Expected return on plan assets	(3,523		)	(3,648		)	(7,055		)	(7,275		)
Settlements	—			269			—			269
Amortization of deferred items	119			583			239			1,177
Total net periodic pension benefit (gain) cost	$	(607	)	$	212		$	(1,218	)	$	216