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Stock-Based Compensation (Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Grants In Period, Weighted Average Grant Date Fair Value) (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Restricted stock |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Granted (in dollars per share) | $ 45.56 | $ 43.57 | $ 26.49
Restricted stock | Consumers Energy Company |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Granted (in dollars per share) | 45.53 | 43.57 | 26.51
Restricted stock units |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Granted (in dollars per share) | 49.76 | 50.35 | 41.77
Restricted stock units | Consumers Energy Company |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Granted (in dollars per share) | $ 49.70 | $ 51.15 | $ 42.01

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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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