
9.	EMPLOYEE BENEFIT PLANS

The components of net periodic benefit cost (credit) related to our defined benefit plans were as follows (in millions):



	Pension Plans						Other Postretirement Benefit Plans
	2018			2017			2018			2017
Three months ended September 30:
Service cost	$	33		$	31		$	2		$	1
Interest cost	22			21			2			3
Expected return on plan assets	(40		)	(37		)	—			—
Amortization of:
Net actuarial (gain) loss	16			13			(1		)	—
Prior service credit	(5		)	(5		)	(2		)	(4		)
Special charges	2			3			—			—
Net periodic benefit cost	$	28		$	26		$	1		$	—

Nine months ended September 30:
Service cost	$	100		$	92		$	5		$	4
Interest cost	68			64			7			8
Expected return on plan assets	(122		)	(112		)	—			—
Amortization of:
Net actuarial (gain) loss	49			40			(2		)	(2		)
Prior service credit	(14		)	(15		)	(8		)	(12		)
Special charges	7			3			—			—
Net periodic benefit cost (credit)	$	88		$	72		$	2		$	(2	)

The components of net periodic benefit cost (credit) other than the service cost component (i.e., the non-service cost components) are included in the line item other income, net in the statements of income.

We contributed $132 million and $104 million, respectively, to our pension plans and $15 million and $17 million, respectively, to our other postretirement benefit plans during the nine months ended September 30, 2018 and 2017. Of the $132 million contributed to our pension plans during the nine months ended September 30, 2018, $110 million was discretionary and was contributed during the third quarter of 2018.

As a result of the discretionary pension contributions discussed above, our expected contributions to our pension plans have increased to $141 million for 2018. Our anticipated contributions to our other postretirement benefit plans during 2018 have not changed from the amount previously disclosed in our financial statements for the year ended December 31, 2017.