EMPLOYEE BENEFIT PLANS

NuStar’s Pension Plan is a qualified non-contributory defined benefit pension plan that provides eligible U.S. employees with retirement income as calculated under a cash balance formula. NuStar’s Excess Pension Plan is a nonqualified deferred compensation plan that provides benefits to a select group of management or other highly compensated employees. The Pension Plan and Excess Pension Plan are collectively referred to as the Pension Plans. In September 2018, we contributed $11.0 million to the Pension Plans.

We also sponsor a contributory medical benefits plan for U.S. employees who retired prior to April 1, 2014. For employees who retire on or after April 1, 2014, we provide partial reimbursement for eligible third-party health care premiums.

The components of net periodic benefit cost (income) related to our Pension Plans and other postretirement benefit plans were as follows:



	Pension Plans						Other Postretirement Benefit Plans
	2018			2017			2018			2017
	(Thousands of Dollars)
For the three months ended September 30:
Service cost	$	2,405		$	2,239		$	126		$	115
Interest cost	1,206			1,127			107			107
Expected return on assets	(1,854		)	(1,603		)	—			—
Amortization of prior service credit	(515		)	(515		)	(286		)	(286		)
Amortization of net loss	544			371			53			47
Net periodic benefit cost (income)	$	1,786		$	1,619		$	—		$	(17	)

For the nine months ended September 30:
Service cost	$	7,216		$	6,717		$	378		$	341
Interest cost	3,618			3,381			322			323
Expected return on assets	(5,563		)	(4,808		)	—			—
Amortization of prior service credit	(1,543		)	(1,546		)	(859		)	(858		)
Amortization of net loss	1,631			1,113			160			143
Net periodic benefit cost (income)	$	5,359		$	4,857		$	1		$	(51	)