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Retirement Benefits (Schedule Of Expected Benefit Payments) (Details) $ in Millions | Dec. 31, 2015 USD ($)
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Pension Plan [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Benefit Payments, 2016 | $ 141
Benefit Payments, 2017 | 146
Benefit Payments, 2018 | 152
Benefit Payments, 2019 | 156
Benefit Payments, 2020 | 159
Benefit Payments, 2021-2025 | 815
Pension Plan [Member] | Consumers Energy Company [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Benefit Payments, 2016 | 137
Benefit Payments, 2017 | 142
Benefit Payments, 2018 | 148
Benefit Payments, 2019 | 152
Benefit Payments, 2020 | 155
Benefit Payments, 2021-2025 | 793
DB SERP [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Benefit Payments, 2016 | 8
Benefit Payments, 2017 | 8
Benefit Payments, 2018 | 8
Benefit Payments, 2019 | 9
Benefit Payments, 2020 | 10
Benefit Payments, 2021-2025 | 50
DB SERP [Member] | Consumers Energy Company [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Benefit Payments, 2016 | 5
Benefit Payments, 2017 | 5
Benefit Payments, 2018 | 5
Benefit Payments, 2019 | 5
Benefit Payments, 2020 | 6
Benefit Payments, 2021-2025 | 30
OPEB [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Benefit Payments, 2016 | 53
Benefit Payments, 2017 | 57
Benefit Payments, 2018 | 59
Benefit Payments, 2019 | 63
Benefit Payments, 2020 | 65
Benefit Payments, 2021-2025 | 353
OPEB [Member] | Consumers Energy Company [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Benefit Payments, 2016 | 51
Benefit Payments, 2017 | 55
Benefit Payments, 2018 | 57
Benefit Payments, 2019 | 61
Benefit Payments, 2020 | 63
Benefit Payments, 2021-2025 | $ 341

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- Definition Amount of benefits from a defined benefit plan expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition Amount of benefits from a defined benefit plan expected to be paid in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition Amount of benefits from a defined benefit plan expected to be paid in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition Amount of benefits from a defined benefit plan expected to be paid in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition Amount of benefits from a defined benefit plan expected to be paid in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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