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Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2022 | Mar. 31, 2021
DB Pension Plans |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |
Service cost | $ 12 | $ 14
Interest cost | 18 | 15
Expected return on plan assets | (52) | (52)
Amortization of |  |
Net loss | 17 | 25
Prior service cost (credit) | 1 | 1
Settlement loss | 2 | 1
Net periodic cost (credit) | (2) | 4
DB Pension Plans | Consumers Energy Company |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |
Service cost | 12 | 13
Interest cost | 16 | 14
Expected return on plan assets | (49) | (49)
Amortization of |  |
Net loss | 16 | 25
Prior service cost (credit) | 1 | 1
Settlement loss | 2 | 1
Net periodic cost (credit) | (2) | 5
OPEB Plan |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |
Service cost | 4 | 4
Interest cost | 7 | 6
Expected return on plan assets | (29) | (27)
Amortization of |  |
Net loss | 0 | 2
Prior service cost (credit) | (12) | (13)
Settlement loss | 0 | 0
Net periodic cost (credit) | (30) | (28)
OPEB Plan | Consumers Energy Company |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |
Service cost | 4 | 4
Interest cost | 7 | 6
Expected return on plan assets | (27) | (25)
Amortization of |  |
Net loss | 0 | 2
Prior service cost (credit) | (12) | (13)
Settlement loss | 0 | 0
Net periodic cost (credit) | $ (28) | $ (26)

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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123453770&loc=SL108413299-114919 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(4) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2709-114920 + Details
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- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123453770&loc=SL108413299-114919 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2709-114920 + Details
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