XML 74 R41.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Plant, Property, and Equipment (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items] |
Schedule Of Property, Plant And Equipment | Presented in the following table are details of CMS Energy’s and Consumers’ plant, property, and equipment:
In Millions |
December 31 | Estimated Depreciable Life in Years | 2018 |  | 2017 |
CMS Energy, including Consumers |  |  |  |  |  |  |
Plant, property, and equipment, gross |  |  |  |  |  |  |
Consumers | 3 | — | 125 |  | $ | 23,963 |  |  | $ | 22,318 |
Enterprises |  |  |  |  |  |  |
Independent power production | 3 | — | 35 |  | 410 |  |  | 163 |
Other | 3 | — | 5 |  | 2 |  |  | 4 |
Other | 1 | — | 7 |  | 25 |  |  | 21 |
Plant, property, and equipment, gross |  |  |  |  | $ | 24,400 |  |  | $ | 22,506 |
Construction work in progress |  |  |  |  | 763 |  |  | 765 |
Accumulated depreciation and amortization |  |  |  |  | (7,037 | ) |  | (6,510 | )
Total plant, property, and equipment |  |  |  |  | $ | 18,126 |  |  | $ | 16,761 |
Consumers |  |  |  |  |  |  |
Plant, property, and equipment, gross |  |  |  |  |  |  |
Electric |  |  |  |  |  |  |
Generation | 22 | — | 125 |  | $ | 6,305 |  |  | $ | 6,025 |
Distribution | 20 | — | 75 |  | 7,957 |  |  | 7,603 |
Transmission | 46 | — | 75 |  | 154 |  |  | 66 |
Other | 5 | — | 50 |  | 1,316 |  |  | 1,229 |
Assets under capital leases and financing obligation 1 |  |  |  |  | 295 |  |  | 298 |
Gas |  |  |  |  |  |  |
Distribution | 20 | — | 85 |  | 4,651 |  |  | 4,182 |
Transmission | 17 | — | 75 |  | 1,521 |  |  | 1,278 |
Underground storage facilities 2 | 27 | — | 75 |  | 910 |  |  | 842 |
Other | 5 | — | 50 |  | 823 |  |  | 764 |
Capital leases 1 |  |  |  |  | 14 |  |  | 14 |
Other non‑utility property | 3 | — | 51 |  | 17 |  |  | 17 |
Plant, property, and equipment, gross |  |  |  |  | $ | 23,963 |  |  | $ | 22,318 |
Construction work in progress |  |  |  |  | 756 |  |  | 753 |
Accumulated depreciation and amortization |  |  |  |  | (6,958 | ) |  | (6,441 | )
Total plant, property, and equipment 3 |  |  |  |  | $ | 17,761 |  |  | $ | 16,630 |
1 | For information regarding the amortization terms of Consumers’ assets under capital leases and financing obligation, see Note 10, Leases and Palisades Financing.
2 | Underground storage includes base natural gas of $26 million at December 31, 2018 and 2017. Base natural gas is not subject to depreciation.
3 | For the year ended December 31, 2018, Consumers’ plant additions were $1.8 billion and plant retirements were $190 million. For the year ended December 31, 2017, Consumers’ plant additions were $1.7 billion and plant retirements were $214 million
Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization Table | Presented in the following table are further details about CMS Energy’s and Consumers’ accumulated depreciation and amortization:
In Millions |
December 31 | 2018 |  | 2017 |
CMS Energy, including Consumers |  |  |  |
Utility plant assets |  | $ | 6,956 |  |  | $ | 6,439 |
Non-utility plant assets |  | 81 |  |  | 71 |
Consumers |  |  |  |
Utility plant assets |  | $ | 6,956 |  |  | $ | 6,439 |
Non-utility plant assets |  | 2 |  |  | 2 |
Schedule Of Depreciation And Amortization | Presented in the following table are the components of CMS Energy’s and Consumers’ depreciation and amortization expense:
In Millions |
Years Ended December 31 | 2018 |  | 2017 |  | 2016 |
CMS Energy, including Consumers |  |  |  |  |  |
Depreciation expense – plant, property, and equipment |  | $ | 778 |  |  | $ | 739 |  |  | $ | 687 |
Amortization expense |  |  |  |  |  |
Software |  | 127 |  |  | 114 |  |  | 96 |
Other intangible assets |  | 3 |  |  | 3 |  |  | 3 |
Securitized regulatory assets |  | 25 |  |  | 25 |  |  | 25 |
Total depreciation and amortization expense |  | $ | 933 |  |  | $ | 881 |  |  | $ | 811 |
Consumers |  |  |  |  |  |
Depreciation expense – plant, property, and equipment |  | $ | 768 |  |  | $ | 732 |  |  | $ | 680 |
Amortization expense |  |  |  |  |  |
Software |  | 125 |  |  | 112 |  |  | 95 |
Other intangible assets |  | 3 |  |  | 3 |  |  | 3 |
Securitized regulatory assets |  | 25 |  |  | 25 |  |  | 25 |
Total depreciation and amortization expense |  | $ | 921 |  |  | $ | 872 |  |  | $ | 803 |
Schedule Of Estimated Amortization Expense For Intangibles | Presented in the following table is CMS Energy’s and Consumers’ estimated amortization expense on intangible assets for each of the next five years:
In Millions |
| 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |
CMS Energy, including Consumers |  |  |  |  |  |  |  |  |  |
Intangible asset amortization expense |  | $ | 132 |  |  | $ | 122 |  |  | $ | 108 |  |  | $ | 95 |  |  | $ | 74 |
Consumers |  |  |  |  |  |  |  |  |  |
Intangible asset amortization expense |  | $ | 130 |  |  | $ | 120 |  |  | $ | 106 |  |  | $ | 94 |  |  | $ | 74 |
Schedule of Finite-Lived Intangible Assets by Major Class Table | Included in net plant, property, and equipment are intangible assets. Presented in the following table are details about CMS Energy’s and Consumers’ intangible assets:
In Millions |
|  | December 31, 2018 |  | December 31, 2017
Description | Amortization Life in Years | Gross Cost 1 |  | Accumulated Amortization |  |  | Gross Cost 1 |  | Accumulated Amortization |
CMS Energy, including Consumers |  |  |  |  |  |  |  |  |
Software development | 1 | — | 15 |  | $ | 1,024 |  |  | $ | 603 |  |  |  | $ | 950 |  |  | $ | 481 |
Rights of way | 50 | — | 85 |  | 167 |  |  | 52 |  |  |  | 162 |  |  | 50 |
Franchises and consents | 5 | — | 30 |  | 15 |  |  | 9 |  |  |  | 14 |  |  | 8 |
Leasehold improvements | various 2 |  | 9 |  |  | 7 |  |  |  | 9 |  |  | 7 |
Other intangibles | various |  | 27 |  |  | 15 |  |  |  | 23 |  |  | 15 |
Total |  |  |  |  | $ | 1,242 |  |  | $ | 686 |  |  |  | $ | 1,158 |  |  | $ | 561 |
Consumers |  |  |  |  |  |  |  |  |  |  |  |
Software development | 3 | — | 15 |  | $ | 1,009 |  |  | $ | 595 |  |  |  | $ | 937 |  |  | $ | 475 |
Rights of way | 50 | — | 85 |  | 167 |  |  | 52 |  |  |  | 162 |  |  | 50 |
Franchises and consents | 5 | — | 30 |  | 15 |  |  | 9 |  |  |  | 14 |  |  | 8 |
Leasehold improvements | various 2 |  | 9 |  |  | 7 |  |  |  | 9 |  |  | 7 |
Other intangibles | various |  | 26 |  |  | 15 |  |  |  | 21 |  |  | 15 |
Total |  |  |  |  | $ | 1,226 |  |  | $ | 678 |  |  |  | $ | 1,143 |  |  | $ | 555 |
1 | For the year ended December 31, 2018, Consumers’ intangible asset additions were $90 million and intangible asset retirements were $7 million. For the year ended December 31, 2017, Consumers’ intangible asset additions were $100 million and there were no intangible asset retirements.
2 | Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended.
Consumers Energy Company |
Public Utility, Property, Plant and Equipment [Line Items] |
Schedule Of Property, Plant And Equipment | Presented in the following table are details of CMS Energy’s and Consumers’ plant, property, and equipment:
In Millions |
December 31 | Estimated Depreciable Life in Years | 2018 |  | 2017 |
CMS Energy, including Consumers |  |  |  |  |  |  |
Plant, property, and equipment, gross |  |  |  |  |  |  |
Consumers | 3 | — | 125 |  | $ | 23,963 |  |  | $ | 22,318 |
Enterprises |  |  |  |  |  |  |
Independent power production | 3 | — | 35 |  | 410 |  |  | 163 |
Other | 3 | — | 5 |  | 2 |  |  | 4 |
Other | 1 | — | 7 |  | 25 |  |  | 21 |
Plant, property, and equipment, gross |  |  |  |  | $ | 24,400 |  |  | $ | 22,506 |
Construction work in progress |  |  |  |  | 763 |  |  | 765 |
Accumulated depreciation and amortization |  |  |  |  | (7,037 | ) |  | (6,510 | )
Total plant, property, and equipment |  |  |  |  | $ | 18,126 |  |  | $ | 16,761 |
Consumers |  |  |  |  |  |  |
Plant, property, and equipment, gross |  |  |  |  |  |  |
Electric |  |  |  |  |  |  |
Generation | 22 | — | 125 |  | $ | 6,305 |  |  | $ | 6,025 |
Distribution | 20 | — | 75 |  | 7,957 |  |  | 7,603 |
Transmission | 46 | — | 75 |  | 154 |  |  | 66 |
Other | 5 | — | 50 |  | 1,316 |  |  | 1,229 |
Assets under capital leases and financing obligation 1 |  |  |  |  | 295 |  |  | 298 |
Gas |  |  |  |  |  |  |
Distribution | 20 | — | 85 |  | 4,651 |  |  | 4,182 |
Transmission | 17 | — | 75 |  | 1,521 |  |  | 1,278 |
Underground storage facilities 2 | 27 | — | 75 |  | 910 |  |  | 842 |
Other | 5 | — | 50 |  | 823 |  |  | 764 |
Capital leases 1 |  |  |  |  | 14 |  |  | 14 |
Other non‑utility property | 3 | — | 51 |  | 17 |  |  | 17 |
Plant, property, and equipment, gross |  |  |  |  | $ | 23,963 |  |  | $ | 22,318 |
Construction work in progress |  |  |  |  | 756 |  |  | 753 |
Accumulated depreciation and amortization |  |  |  |  | (6,958 | ) |  | (6,441 | )
Total plant, property, and equipment 3 |  |  |  |  | $ | 17,761 |  |  | $ | 16,630 |
1 | For information regarding the amortization terms of Consumers’ assets under capital leases and financing obligation, see Note 10, Leases and Palisades Financing.
2 | Underground storage includes base natural gas of $26 million at December 31, 2018 and 2017. Base natural gas is not subject to depreciation.
3 | For the year ended December 31, 2018, Consumers’ plant additions were $1.8 billion and plant retirements were $190 million. For the year ended December 31, 2017, Consumers’ plant additions were $1.7 billion and plant retirements were $214 million.
Public Utilities, Allowance For Funds Used During Construction Average Rate | Presented in the following table are Consumers’ average AFUDC capitalization rates:
Years Ended December 31 | 2018 |  | 2017 |  | 2016 |
Electric | 6.9 | % | 6.8 | % | 7.3 | %
Gas | 5.9 |  | 6.0 |  | 6.2 |
Schedule of Capital Leased Asssets | Assets Under Capital Leases and Financing Obligation: Presented in the following table are further details about changes in Consumers’ assets under capital leases and financing obligation:
In Millions |
Years Ended December 31 | 2018 |  | 2017 |
Consumers |  |  |  |
Balance at beginning of period |  | $ | 312 |  |  | $ | 310 |
Additions |  | — |  |  | 3 |
Net retirements and other adjustments |  | (3 | ) |  | (1 | )
Balance at end of period |  | $ | 309 |  |  | $ | 312 |
Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization Table | Presented in the following table are further details about CMS Energy’s and Consumers’ accumulated depreciation and amortization:
In Millions |
December 31 | 2018 |  | 2017 |
CMS Energy, including Consumers |  |  |  |
Utility plant assets |  | $ | 6,956 |  |  | $ | 6,439 |
Non-utility plant assets |  | 81 |  |  | 71 |
Consumers |  |  |  |
Utility plant assets |  | $ | 6,956 |  |  | $ | 6,439 |
Non-utility plant assets |  | 2 |  |  | 2 |
Public Utilities Property Plant and Equipment Schedule of Composite Depreciation Rate Table | Presented in the following table are the composite depreciation rates for Consumers’ segment properties:
Years Ended December 31 | 2018 |  | 2017 |  | 2016 |
Electric utility property |  | 3.9 | % |  | 3.9 | % |  | 3.9 | %
Gas utility property |  | 2.9 |  |  | 2.9 |  |  | 2.9 |
Other property |  | 10.1 |  |  | 10.0 |  |  | 9.8 |
Schedule Of Depreciation And Amortization | Presented in the following table are the components of CMS Energy’s and Consumers’ depreciation and amortization expense:
In Millions |
Years Ended December 31 | 2018 |  | 2017 |  | 2016 |
CMS Energy, including Consumers |  |  |  |  |  |
Depreciation expense – plant, property, and equipment |  | $ | 778 |  |  | $ | 739 |  |  | $ | 687 |
Amortization expense |  |  |  |  |  |
Software |  | 127 |  |  | 114 |  |  | 96 |
Other intangible assets |  | 3 |  |  | 3 |  |  | 3 |
Securitized regulatory assets |  | 25 |  |  | 25 |  |  | 25 |
Total depreciation and amortization expense |  | $ | 933 |  |  | $ | 881 |  |  | $ | 811 |
Consumers |  |  |  |  |  |
Depreciation expense – plant, property, and equipment |  | $ | 768 |  |  | $ | 732 |  |  | $ | 680 |
Amortization expense |  |  |  |  |  |
Software |  | 125 |  |  | 112 |  |  | 95 |
Other intangible assets |  | 3 |  |  | 3 |  |  | 3 |
Securitized regulatory assets |  | 25 |  |  | 25 |  |  | 25 |
Total depreciation and amortization expense |  | $ | 921 |  |  | $ | 872 |  |  | $ | 803 |
Schedule Of Estimated Amortization Expense For Intangibles | Presented in the following table is CMS Energy’s and Consumers’ estimated amortization expense on intangible assets for each of the next five years:
In Millions |
| 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 |
CMS Energy, including Consumers |  |  |  |  |  |  |  |  |  |
Intangible asset amortization expense |  | $ | 132 |  |  | $ | 122 |  |  | $ | 108 |  |  | $ | 95 |  |  | $ | 74 |
Consumers |  |  |  |  |  |  |  |  |  |
Intangible asset amortization expense |  | $ | 130 |  |  | $ | 120 |  |  | $ | 106 |  |  | $ | 94 |  |  | $ | 74 |
Schedule of Finite-Lived Intangible Assets by Major Class Table | Included in net plant, property, and equipment are intangible assets. Presented in the following table are details about CMS Energy’s and Consumers’ intangible assets:
In Millions |
|  | December 31, 2018 |  | December 31, 2017
Description | Amortization Life in Years | Gross Cost 1 |  | Accumulated Amortization |  |  | Gross Cost 1 |  | Accumulated Amortization |
CMS Energy, including Consumers |  |  |  |  |  |  |  |  |
Software development | 1 | — | 15 |  | $ | 1,024 |  |  | $ | 603 |  |  |  | $ | 950 |  |  | $ | 481 |
Rights of way | 50 | — | 85 |  | 167 |  |  | 52 |  |  |  | 162 |  |  | 50 |
Franchises and consents | 5 | — | 30 |  | 15 |  |  | 9 |  |  |  | 14 |  |  | 8 |
Leasehold improvements | various 2 |  | 9 |  |  | 7 |  |  |  | 9 |  |  | 7 |
Other intangibles | various |  | 27 |  |  | 15 |  |  |  | 23 |  |  | 15 |
Total |  |  |  |  | $ | 1,242 |  |  | $ | 686 |  |  |  | $ | 1,158 |  |  | $ | 561 |
Consumers |  |  |  |  |  |  |  |  |  |  |  |
Software development | 3 | — | 15 |  | $ | 1,009 |  |  | $ | 595 |  |  |  | $ | 937 |  |  | $ | 475 |
Rights of way | 50 | — | 85 |  | 167 |  |  | 52 |  |  |  | 162 |  |  | 50 |
Franchises and consents | 5 | — | 30 |  | 15 |  |  | 9 |  |  |  | 14 |  |  | 8 |
Leasehold improvements | various 2 |  | 9 |  |  | 7 |  |  |  | 9 |  |  | 7 |
Other intangibles | various |  | 26 |  |  | 15 |  |  |  | 21 |  |  | 15 |
Total |  |  |  |  | $ | 1,226 |  |  | $ | 678 |  |  |  | $ | 1,143 |  |  | $ | 555 |
1 | For the year ended December 31, 2018, Consumers’ intangible asset additions were $90 million and intangible asset retirements were $7 million. For the year ended December 31, 2017, Consumers’ intangible asset additions were $100 million and there were no intangible asset retirements.
2 | Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended.
Jointly Owned Regulated Utility Facilities | Presented in the following table are Consumers’ investments in jointly owned regulated utility facilities at December 31, 2018:
In Millions, Except Ownership Share |
J.H. Campbell Unit 3 |  | Ludington |  |  | Other |
Ownership share |  | 93.3 | % |  | 51.0 | % |  | various |
Utility plant in service |  | $ | 1,688 |  |  | $ | 411 |  |  | $ | 226 |
Accumulated depreciation |  | (670 | ) |  | (155 | ) |  | (70 | )
Construction work in progress |  | 23 |  |  | 110 |  |  | 16 |
Net investment |  | $ | 1,041 |  |  | $ | 366 |  |  | $ | 172 |

X
- Definition Tabular disclosure of the average rate of allowance for funds used during construction. + References No definition available. + Details
Name: | cms_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAverageRateTableTextBlock
Namespace Prefix: | cms_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization Table Text Block + References No definition available. + Details
Name: | cms_PublicUtilitiesPropertyPlantandEquipmentScheduleofAccumulatedDepreciationandAmortizationTableTextBlockTableTextBlock
Namespace Prefix: | cms_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the electric, gas, and other composite depreciation rates for public utility plants in service for each year an income statement is presented. + References No definition available. + Details
Name: | cms_PublicUtilitiesPropertyPlantandEquipmentScheduleofCompositeDepreciationRateTableTextBlockTableTextBlock
Namespace Prefix: | cms_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Depriciation And Amortization [Table Text Block] + References No definition available. + Details
Name: | cms_ScheduleOfDepriciationAndAmortizationTableTextBlock
Namespace Prefix: | cms_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of amortization expense of assets, excluding financial assets, that lack physical substance, having a limited useful life. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation and depletion expense and method used, including composite depreciation, and accumulated deprecation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(13)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
Name: | us-gaap_PropertyPlantAndEquipmentTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- 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
Name: | us-gaap_PublicUtilityPropertyPlantAndEquipmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of long-lived, depreciable assets that are subject to a lease meeting the criteria for capitalization and are used in the normal conduct of business to produce goods and services. Examples may include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 + Details
Name: | us-gaap_ScheduleOfCapitalLeasedAsssetsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of assets, excluding financial assets and goodwill, lacking physical substance with a finite life, by either major class or business segment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
Name: | us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=115995737&loc=d3e659983-123033 + Details
Name: | us-gaap_ScheduleOfJointlyOwnedUtilityPlantsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=cms_ConsumersEnergyCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |