9. Retirement Plans

Components of net periodic pension cost consisted of the following:

	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2018			2017			2018			2017
	(In millions)
Service cost	$	10		$	14		$	24		$	28
Interest cost		24			26			47			52
Expected return on plan assets		(49	)		(42	)		(98	)		(83	)
Amortization of unrecognized net actuarial losses		9			16			21			33
Curtailment gains		—			—			(2	)		—
Settlement loss		—			7			—			7
Pension (income) expense	$	(6	)	$	21		$	(8	)	$	37

In the first quarter of 2018, we recorded curtailment gains of $18 million to Accumulated other comprehensive income (loss) and $2 million to the Statement of Consolidated Income following workforce reductions. In connection with this curtailment, as required under accounting standards, we remeasured our U.S. retirement plans and recorded a total decrease of $125 million in the Corporation’s U.S. pension liabilities. This reduction was primarily driven by a change in weighted average discount rates used to measure the liabilities. There was no change to the weighted average expected long-term rate of return on plan assets.

For the full year 2018, we now forecast pension service costs of approximately $45 million and net non-service pension costs of approximately $60 million of income, which is comprised of interest cost of approximately $95 million, amortization of unrecognized net actuarial losses of approximately $40 million and estimated expected return on plan assets of approximately $195 million.

Net non-service pension costs included in Other, net in the Statement of Consolidated Income for the three and six months ended June 30, 2018 was income of $16 million and $32 million, respectively, compared to expenses of $7 million and $9 million for the three and six months ended June 30, 2017, respectively.

In 2018, we expect to contribute $47 million to our funded pension plans. In the six months ended June 30, 2018, we have contributed $25 million to these plans.