EMPLOYEE BENEFIT PLANS (Tables)

3 Months Ended

Mar. 31, 2018

EMPLOYEE BENEFIT PLANS

Schedule of the postretirement medical benefit and postemployment medical benefit obligations

The postretirement medical benefit and postemployment medical benefit obligations are determined annually (during the fourth quarter) by an independent actuary and are included in accumulated postretirement benefit and postemployment obligations on our consolidated statements of financial position as follows (dollars in thousands):

	March 31,
	2018
Postretirement medical benefit obligation at beginning of period	$	8,455
Service cost		152
Interest cost		71
Benefit payments (net of contributions by participants)		(103)
Postretirement medical benefit obligation at end of period	$	8,575
Postemployment medical benefit obligation at end of period		367
Total postretirement and postemployment medical obligations at end of period	$	8,942

Schedule of the net unrecognized actuarial gains and losses related to the postretirement medical benefit obligation that are included in accumulated other comprehensive income

The net unrecognized actuarial gains and losses related to the postretirement medical benefit obligations are included in accumulated other comprehensive income as follows (dollars in thousands):

	March 31,
	2018
Amounts included in accumulated other comprehensive income at beginning of year	$	(369)
Amortization of prior service credit into other income (expense)		(20)
Amounts included in accumulated other comprehensive income at end of year	$	(389)