Employee Retirement Plans

The components of net pension and postretirement benefits costs are summarized in the following table:



	Three months ended September 30,						Nine months ended September 30,
(millions)	2013			2012			2013			2012
Pension:
Service cost of benefits earned	$	10		$	8		$	29		$	23
Interest cost on projected benefit obligation	16			16			47			48
Expected return on plan assets	(19		)	(18		)	(57		)	(52		)
Net amortization	11			9			34			26
Net pension cost	$	18		$	15		$	53		$	45
Postretirement:
Service cost of benefits earned	$	1		$	1		$	3		$	3
Interest cost on projected benefit obligation	2			2			5			6
Net amortization	(9		)	(9		)	(26		)	(27		)
Net postretirement cost	$	(6	)	$	(6	)	$	(18	)	$	(18	)

We expect contributions to our pension plans in 2013 to be approximately $72 million. During the first nine months of 2013, we made cash contributions of $50 million to the USG Corporation Retirement Plan Trust, $15 million to our pension plan in Canada and $6 million, in aggregate, to certain other domestic and foreign pension plans.

In September 2013, we communicated to certain terminated vested participants in our USG Corporation Retirement Plan an option to receive a lump sum payment for their accrued benefits. The option commenced on October 1, 2013 and expires on November 15, 2013. For participants who elect this option, payments would be made in December 2013 and we expect to incur a settlement charge at that time, which would be calculated based upon prevailing discount rates at the settlement date, December 1, 2013.