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Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Aug. 31, 2020 | Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
DB Pension Plans |  |  |  |  |
Net periodic cost (credit) |  |  |  |  |
Service cost |  | $ 12,000,000 | $ 11,000,000 | $ 37,000,000 | $ 31,000,000
Interest cost |  | 20,000,000 | 24,000,000 | 61,000,000 | 73,000,000
Expected return on plan assets |  | (47,000,000) | (40,000,000) | (143,000,000) | (121,000,000)
Settlement loss | $ 36,000,000 | 1,000,000 | 0 | 1,000,000 | 0
Amortization of: |  |  |  |  |
Net loss |  | 23,000,000 | 12,000,000 | 67,000,000 | 36,000,000
Prior service cost (credit) |  | 0 | 0 | 1,000,000 | 1,000,000
Net periodic cost (credit) |  | 9,000,000 | 7,000,000 | 24,000,000 | 20,000,000
DB Pension Plans | Consumers Energy Company |  |  |  |  |
Net periodic cost (credit) |  |  |  |  |
Service cost |  | 12,000,000 | 10,000,000 | 36,000,000 | 30,000,000
Interest cost |  | 20,000,000 | 23,000,000 | 59,000,000 | 69,000,000
Expected return on plan assets |  | (45,000,000) | (38,000,000) | (136,000,000) | (114,000,000)
Amortization of: |  |  |  |  |
Net loss |  | 22,000,000 | 12,000,000 | 64,000,000 | 35,000,000
Prior service cost (credit) |  | 0 | 0 | 1,000,000 | 1,000,000
Net periodic cost (credit) |  | 9,000,000 | 7,000,000 | 24,000,000 | 21,000,000
OPEB Plan |  |  |  |  |
Net periodic cost (credit) |  |  |  |  |
Service cost |  | 4,000,000 | 3,000,000 | 12,000,000 | 10,000,000
Interest cost |  | 8,000,000 | 11,000,000 | 25,000,000 | 31,000,000
Expected return on plan assets |  | (25,000,000) | (22,000,000) | (75,000,000) | (66,000,000)
Settlement loss |  | 0 | 0 | 0 | 0
Amortization of: |  |  |  |  |
Net loss |  | 4,000,000 | 7,000,000 | 11,000,000 | 20,000,000
Prior service cost (credit) |  | (14,000,000) | (16,000,000) | (42,000,000) | (47,000,000)
Net periodic cost (credit) |  | (23,000,000) | (17,000,000) | (69,000,000) | (52,000,000)
OPEB Plan | Consumers Energy Company |  |  |  |  |
Net periodic cost (credit) |  |  |  |  |
Service cost |  | 3,000,000 | 3,000,000 | 11,000,000 | 10,000,000
Interest cost |  | 8,000,000 | 10,000,000 | 24,000,000 | 30,000,000
Expected return on plan assets |  | (23,000,000) | (21,000,000) | (70,000,000) | (62,000,000)
Amortization of: |  |  |  |  |
Net loss |  | 4,000,000 | 7,000,000 | 11,000,000 | 20,000,000
Prior service cost (credit) |  | (13,000,000) | (15,000,000) | (40,000,000) | (46,000,000)
Net periodic cost (credit) |  | $ (21,000,000) | $ (16,000,000) | $ (64,000,000) | $ (48,000,000)

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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(7) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
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