E. I. du Pont de Nemours and Company Notes to the Consolidated Financial Statements (continued) Summarized information on the company's pension and other post employment benefit plans is as follows: 1.The benefit obligation and the fair value of plan assets at the beginning of the period September 1 through December 31, 2017, reflects the remeasurement of the plans at the Merger Effectiveness Time. 2.In the fourth quarter of 2017, about $140 million of lump-sum payments were made from the principal U.S. pension plan trust fund to a group of separated, vested plan participants who were extended a limited-time opportunity and voluntarily elected to receive their pension benefits in a single lump-sum payment. 3.As of December 31, 2018, and December 31, 2017, $349 million and $389 million respectively of the benefit obligations are supported by funding under the Trust agreement, defined in the "Trust Assets" section below. 4.Includes pension plans maintained around the world where funding is not customary. F-64 Change in Projected Benefit Obligations, Plan Assets and Funded Status Defined Benefit Pension Plans Other Post Employment Benefits Successor Predecessor Successor Predecessor (In millions) For the Year Ended December 31, 2018 For the Period September 1 through December 31, 2017  1 For the Period January 1 through August 31, 2017 For the Year Ended December 31, 2018 For the Period September 1 through December 31, 2017  1 For the Period January 1 through August 31, 2017 Change in benefit obligations: Benefit obligation at beginning of the period $ 25,550 $ 26,036 $ 24,831 $ 2,810 $ 2,772 $ 2,829 Service cost 131 49 92 9 3 6 Interest cost 752 247 524 85 26 60 Plan participants' contributions 10 6 8 38 12 26 Actuarial (gain) loss (1,078) (23) — (172) 68 — Benefits paid 2 (1,747 ) (730 ) (1,118 ) (254 ) (71 ) (192 ) Plan amendments 17 — — — — — Net effects of acquisitions / divestitures / other (12 ) 22 — — — — Effect of foreign exchange rates (209) (57) 429 (2) — 2 Benefit obligations at end of the period $ 23,414 $ 25,550 $ 24,766 $ 2,514 $ 2,810 $ 2,731 Change in plan assets: Fair value of plan assets at beginning of the period $ 20,284 $ 20,395 $ 16,656 $ — $ — $ — Actual return on plan assets (782 ) 549 846 — — — Employer contributions 1,308 68 3,024 216 59 166 Plan participants' contributions 10 6 8 38 12 26 Benefits paid 2 (1,747) (730) (1,118) (254) (71) (192) Net effects of acquisitions / divestitures / other (7 ) 29 — — — — Effect of foreign exchange rates (148) (33) 269 — — — Fair value of plan assets at end of the period $ 18,918 $ 20,284 $ 19,685 $ — $ — $ — Funded status U.S. plan with plan assets $ (2,890 ) $ (3,628 ) $ (3,277 ) $ — $ — $ — Non-U.S. plans with plan assets (488) (447) (609) — — — All other plans  3, 4 (1,118 ) (1,191 ) (1,187 ) (2,514 ) (2,810 ) (2,731 ) Plans of discontinued operations — — (8) — — — Funded status at end of the period $ (4,496 ) $ (5,266 ) $ (5,081 ) $ (2,514 ) $ (2,810 ) $ (2,731 )