9. PENSIONS AND OTHER POSTRETIREMENT BENEFITS

Buckeye Pipe Line Services Company (“Services Company”), which employs the majority of our workforce, sponsors a defined benefit plan, the Retirement Income Guarantee Plan (the “RIGP”), and an unfunded post-retirement benefit plan (the “Retiree Medical Plan”). The components of the net periodic benefit cost for the RIGP and Retiree Medical Plan were as follows for the three months ended September 30, 2013 and 2012 (in thousands):

	RIGP						Retiree Medical Plan
	Three Months Ended						Three Months Ended
	September 30,						September 30,
	2013			2012			2013		2012

Service cost	$	41		$	51		$	166	$	82
Interest cost (credit)	(11		)	206			159		415
Expected return on plan assets	(67		)	(140		)	—		—
Amortization of prior service cost (credit)	—			—			147		(623		)
Amortization of unrecognized losses	239			231			265		319
Actuarial loss due to settlements	230			930			—		—
Net periodic benefit cost	$	432		$	1,278		$	737	$	193

The components of the net periodic benefit cost for the RIGP and the Retiree Medical Plan were as follows for the nine months ended September 30, 2013 and 2012 (in thousands):

	RIGP						Retiree Medical Plan
	Nine Months Ended						Nine Months Ended
	September 30,						September 30,
	2013			2012			2013			2012

Service cost	$	163		$	183		$	323		$	236
Interest cost	403			620			1,056			1,345
Expected return on plan assets	(294		)	(340		)	—			—
Amortization of prior service credit	—			—			(1,218		)	(2,047		)
Amortization of unrecognized losses	924			1,028			895			945
Actuarial loss due to settlements	683			930			—			—
Net periodic benefit cost	$	1,879		$	2,421		$	1,056		$	479

During the three months ended September 30, 2013 and 2012, we contributed approximately $0.3 million and $0.2 million, respectively, in aggregate to the RIGP and Retiree Medical Plans. For the nine months ended September 30, 2013 and 2012, we contributed approximately $1.0 million and $2.7 million, respectively, in aggregate to the RIGP and Retiree Medical Plans.