Postretirement Medical Plan (Tables)

6 Months Ended

Jun. 30, 2019

Postretirement Medical Plan

Schedule of components of net periodic postretirement benefit cost

		Three Months Ended				Six Months Ended
		June 30,				June 30,
		2019		2018		2019		2018
Service cost		$	—	$	197	$	—	$	394
Interest cost			—		220		—		440
Amortization of prior service cost (credit)			—		(1,837)		—		(3,675)
Postretirement medical plan termination (gain) loss			(1,755)		—		(3,510)		—
	Net periodic benefit cost (credit)	$	(1,755)	$	(1,420)	$	(3,510)	$	(2,841)