Postretirement Medical Plan (Tables)

9 Months Ended

Sep. 30, 2015

Postretirement Medical Plan

Schedule of components of net periodic postretirement benefit cost

		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2015		2014		2015		2014
Service cost		$	1,229	$	1,038	$	3,687	$	3,113
Interest cost			482		464		1,446		1,393
Amortization of prior service cost			313		247		939		741
	Net periodic benefit cost	$	2,024	$	1,749	$	6,072	$	5,247