The following table provides a reconciliation of benefit obligations, plan assets, and unfunded status related to our qualified defined benefit pension plans and our retiree medical and life insurance plans: (In millions) Qualified Defined Benefit Pension Plans Retiree Medical and Life Insurance Plans 2011 2010 2011 2010 Change in benefit obligation Beginning balance $ 35,773 $ 32,817 $ 3,046 $ 2,938 Service cost 974 903 32 36 Interest cost 1,918 1,876 162 166 Benefits paid (1,685) (1,592) (363) (352) Actuarial losses (gains) 3,632 2,032 (28) 105 Plan amendments 4 94 11 — Divestitures/curtailments (a) — (357) — (10) Medicare Part D subsidy — — 2 18 Participants’ contributions — — 161 145 Ending balance $ 40,616 $ 35,773 $ 3,023 $ 3,046 Change in plan assets Beginning balance at fair value $ 25,345 $ 22,154 $ 1,833 $ 1,630 Actual return on plan assets 1,349 2,886 114 86 Benefits paid (1,685) (1,592) (363) (352) Our contributions 2,285 2,240 — 311 Divestitures and other (a) (2) (343) 2 (5) Medicare Part D subsidy — — 2 18 Participants’ contributions — — 161 145 Ending balance at fair value $ 27,292 $ 25,345 $ 1,749 $ 1,833 Unfunded status of the plans $(13,324) $(10,428) $(1,274) $(1,213) Amounts recognized in the Balance Sheets Prepaid pension asset $ 178 $ 179 $— $— Accrued postretirement benefit liabilities (13,502) (10,607) (1,274) (1,213) Accumulated other comprehensive loss (pre-tax) related to: Net actuarial losses 15,698 12,263 648 684 Prior service cost (credit) 377 455 (10) (37) (a) Primarily reflects the transfer of assets and liabilities associated with the 2010 sale of EIG (Note 14). An expense of $109 million was recognized in connection with this settlement, which reduced the gain on sale. The accumulated benefit obligation (ABO) for all qualified defined benefit pension plans was $35.7 billion and $31.4 billion at December 31, 2011 and 2010. Certain key information related to those plans where ABO was in excess of plan assets as of December 31, 2011 and 2010 is as follows: We also sponsor nonqualified defined benefit plans to provide benefits in excess of qualified plan limits. The aggregate liabilities for these plans at December 31, 2011 and 2010 were $907 million and $850 million, which also represent the plans’ unfunded status. We have set aside certain assets totaling $283 million and $338 million as of December 31, 2011 and 2010 in a Rabbi Trust which we expect to be used to pay obligations under our nonqualified defined benefit plans. In accordance with GAAP, those assets may not be used to offset the amount of the benefit obligation similar to the postretirement benefit plans in the table above. The unrecognized net actuarial losses at December 31, 2011 and 2010 were $476 million and $447 million, and the unrecognized prior service costs were not material. The expense associated with these plans totaled $104 million in 2011, $85 million in 2010, and $76 million in 2009. We also sponsor a small number of other 70 (In millions) 2011 2010 Projected benefit obligation $40,478 $35,640 Accumulated benefit obligation 35,516 31,291 Fair value of plan assets 26,976 25,033