RETIREMENT BENEFITS

The cost to the company of its retirement benefit plans is shown in the following table:



	Three Months Ended June 30												Six Months Ended June 30
	Pension Benefits						Medical and Life Benefits						Pension Benefits						Medical and Life Benefits
$ in millions	2013			2012			2013			2012			2013			2012			2013			2012
Components of net periodic benefit cost
Service cost		$129			$130			$ 9			$ 9			$258			$261			$18			$17
Interest cost	280			296			24			27			559			592			48			54
Expected return on plan assets	(452		)	(427		)	(19		)	(17		)	(905		)	(854		)	(38		)	(34		)
Amortization of:
Prior service credit	(15		)	(14		)	(13		)	(13		)	(29		)	(29		)	(25		)	(25		)
Net loss from previous years	152			107			8			5			304			214			15			10
Other	—			—			—			—			—			2			—			—
Net periodic benefit cost		$ 94			$ 92			$ 9			$ 11			$187			$186			$18			$22

Employer Contributions

The company’s required minimum funding in 2013 for its defined benefit pension plans and its post-retirement benefit plans is approximately $66 million and $110 million, respectively. For the six months ended June 30, 2013, contributions of $543 million have been made to the company’s defined benefit pension plans, including a voluntary contribution of $500 million in April 2013, and contributions of $63 million have been made to the company’s post-retirement benefit plans.

The company also sponsors defined contribution plans. For the three months ended June 30, 2013 and 2012, contributions of $75 million and $76 million, respectively, were made to these plans. For the six months ended June 30, 2013 and 2012, contributions of $150 million and $152 million, respectively, were made to these plans.