Consumers Energy (CMS-PB) 10-Q 26 Oct 17 2017 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 10, 2017
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2,017
Trading Symbol	cms
Entity Registrant Name	CMS Energy Corporation
Entity Central Index Key	811,156
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
CMS Energy [Member]
Entity Common Stock, Shares Outstanding		282,083,585
Consumers Energy Company [Member]
Entity Registrant Name	Consumers Energy Company
Entity Central Index Key	201,533
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		84,108,789

Consolidated Statements Of Inco

Consolidated Statements Of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating Revenue	$ 1,527	$ 1,587	$ 4,805	$ 4,759
Operating Expenses
Fuel for electric generation	144	145	386	367
Purchased and interchange power	426	454	1,132	1,165
Purchased power - related parties	21	22	64	65
Cost of gas sold	47	45	494	490
Maintenance and other operating expenses	304	301	909	890
Depreciation and amortization	193	183	652	597
General taxes	62	62	209	209
Total operating expenses	1,197	1,212	3,846	3,783
Operating Income	330	375	959	976
Other Income (Expense)
Interest income	3	1	10	4
Allowance for equity funds used during construction	1	3	5	9
Income from equity method investees	3	5	10	12
Nonoperating retirement benefits, net	3	11	10	31
Other income	2	2	4	7
Other expense	(2)	(6)	(6)	(13)
Total other income	10	16	33	50
Interest Charges
Interest on long-term debt	101	103	304	306
Other interest expense	10	8	26	22
Allowance for borrowed funds used during construction		(1)	(2)	(4)
Total interest charges	111	110	328	324
Income Before Income Taxes	229	281	664	702
Income Tax Expense	57	95	200	227
Net Income	172	186	464	475
Income Attributable to Noncontrolling Interests			1	1
Net Income Available to Common Stockholders	$ 172	$ 186	$ 463	$ 474
Basic Earnings Per Average Common Share	$ 0.61	$ 0.67	$ 1.65	$ 1.71
Diluted Earnings Per Average Common Share	0.61	0.67	1.65	1.70
Dividends Declared Per Common Share	$ 0.3325	$ 0.3100	$ 0.9975	$ 0.9300
Consumers Energy Company [Member]
Operating Revenue	$ 1,437	$ 1,498	$ 4,536	$ 4,514
Operating Expenses
Fuel for electric generation	115	118	304	290
Purchased and interchange power	424	445	1,124	1,148
Purchased power - related parties	23	23	67	66
Cost of gas sold	42	39	479	477
Maintenance and other operating expenses	274	274	824	816
Depreciation and amortization	191	182	646	592
General taxes	60	61	203	207
Total operating expenses	1,129	1,142	3,647	3,596
Operating Income	308	356	889	918
Other Income (Expense)
Interest income	2	1	8	3
Interest and dividend income - related parties				1
Allowance for equity funds used during construction	1	3	5	9
Nonoperating retirement benefits, net	3	9	8	28
Other income	1	2	15	7
Other expense	(2)	(6)	(6)	(13)
Total other income	5	9	30	35
Interest Charges
Interest on long-term debt	66	65	198	195
Other interest expense	4	3	11	9
Allowance for borrowed funds used during construction		(1)	(2)	(4)
Total interest charges	70	67	207	200
Income Before Income Taxes	243	298	712	753
Income Tax Expense	62	103	216	254
Net Income	181	195	496	499
Preferred Stock Dividends			1	1
Net Income Available to Common Stockholders	$ 181	$ 195	$ 495	$ 498

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income	$ 172	$ 186	$ 464	$ 475
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax		1	1	2
Amortization of prior service credit, net of tax				(1)
Investments
Unrealized gain (loss) on investments, net of tax	1	1	2	1
Other Comprehensive Income (Loss)	1	2	3	2
Comprehensive Income	173	188	467	477
Comprehensive Income Attributable to Noncontrolling Interest			1	1
Comprehensive Income Attributable to CMS Energy	173	188	466	476
Consumers Energy Company [Member]
Net Income	181	195	496	499
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax			1
Investments
Unrealized gain (loss) on investments, net of tax		(2)	2	3
Reclassification adjustments included in net income, net of tax			(8)
Other Comprehensive Income (Loss)		(2)	(5)	3
Comprehensive Income Attributable to CMS Energy	$ 181	$ 193	$ 491	$ 502

Consolidated Statements Of Com4

Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Amortization of net actuarial loss, tax	$ 1		$ 1
Amortization of prior service credit, tax
Unrealized gain (loss) on investments, tax expense (tax benefit)			1
Consumers Energy Company [Member]
Amortization of net actuarial loss, tax
Unrealized gain (loss) on investments, tax expense (tax benefit)		(1)	1	2
Reclassification adjustments included in net income, tax			$ (5)

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities
Net Income	$ 464	$ 475
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	652	597
Deferred income taxes and investment tax credit	198	219
Other non-cash operating activities and reconciling adjustments	78	54
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts and notes receivable and accrued revenue	185	51
Decrease (increase) in inventories	(161)	35
Increase (decrease) in accounts payable and accrued refunds	(6)	(24)
Other current and non-current assets and liabilities	(211)	(166)
Net cash provided by operating activities	1,199	1,241
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,208)	(1,224)
Decrease (increase) in EnerBank notes receivable	(87)	(87)
Proceeds from the sale of EnerBank notes receivable	19
Cost to retire property and other investing activities	(78)	(87)
Net cash used in investing activities	(1,354)	(1,398)
Cash Flows from Financing Activities
Proceeds from issuance of debt	1,108	775
Issuance of common stock	80	69
Net increase (decrease) in EnerBank certificates of deposit	40	64
Payment of dividends on common and preferred stock	(282)	(260)
Retirement of long-term debt	(668)	(215)
Decrease in notes payable	(168)	(174)
Payment of capital lease obligations and other financing costs	(39)	(22)
Net cash provided by (used in) financing activities	71	237
Net Increase (Decrease) in Cash and Cash Equivalents, Including Restricted Amounts	(84)	80
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	257	288
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	173	368
Non-cash transactions
Capital expenditures not paid	153	159
Note receivable recorded for future refund of use taxes paid and capitalized		29
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net Income	496	499
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	646	592
Deferred income taxes and investment tax credit	204	220
Other non-cash operating activities and reconciling adjustments	71	45
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts and notes receivable and accrued revenue	184	72
Decrease (increase) in inventories	(161)	35
Increase (decrease) in accounts payable and accrued refunds	(10)	(31)
Other current and non-current assets and liabilities	(221)	(144)
Net cash provided by operating activities	1,209	1,288
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,196)	(1,214)
Cost to retire property and other investing activities	(82)	(87)
Net cash used in investing activities	(1,278)	(1,301)
Cash Flows from Financing Activities
Proceeds from issuance of debt	534	446
Stockholder contribution	450	275
Payment of dividends on common and preferred stock	(348)	(362)
Retirement of long-term debt	(443)	(185)
Decrease in notes payable	(168)	(174)
Payment of capital lease obligations and other financing costs	(23)	(8)
Net cash provided by (used in) financing activities	2	(8)
Net Increase (Decrease) in Cash and Cash Equivalents, Including Restricted Amounts	(67)	(21)
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	152	71
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	85	50
Non-cash transactions
Capital expenditures not paid	$ 140	145
Note receivable recorded for future refund of use taxes paid and capitalized		$ 29

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 142	$ 235
Restricted cash and cash equivalents	27	19
Accounts receivable and accrued revenue, less allowance	631	821
Notes receivable, less allowance	197	180
Notes receivable held for sale	31	39
Accounts receivable - related parties	12	12
Inventories at average cost
Gas in underground storage	584	446
Materials and supplies	126	119
Generating plant fuel stock	77	61
Deferred property taxes	157	250
Regulatory assets	19	17
Prepayments and other current assets	118	81
Total current assets	2,121	2,280
Plant, Property, and Equipment
Plant, property, and equipment, gross	21,966	21,010
Less accumulated depreciation and amortization	6,403	6,056
Plant, property, and equipment, net	15,563	14,954
Construction work in progress	881	761
Total plant, property, and equipment	16,444	15,715
Other Non-current Assets
Regulatory assets	2,038	2,091
Accounts and notes receivable	1,177	1,118
Investments	71	65
Other	269	353
Total other non-current assets	3,555	3,627
Total Assets	22,120	21,622
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation	980	886
Notes payable	230	398
Accounts payable	624	598
Accounts payable - related parties	8	12
Accrued rate refunds	35	21
Accrued interest	79	98
Accrued taxes	90	348
Regulatory liabilities	85	95
Other current liabilities	130	199
Total current liabilities	2,261	2,655
Non-current Liabilities
Long-term debt	9,024	8,640
Non-current portion of capital leases and financing obligation	97	110
Regulatory liabilities	2,066	2,041
Postretirement benefits	760	789
Asset retirement obligations	443	447
Deferred investment tax credit	88	73
Deferred income taxes	2,501	2,287
Other non-current liabilities	308	290
Total non-current liabilities	15,287	14,677
Commitments and Contingencies (Notes 2 and 3)
Common stockholder's equity
Common stock	3	3
Other paid-in capital	5,013	4,916
Accumulated other comprehensive loss	(47)	(50)
Retained earnings (Accumulated deficit)	(434)	(616)
Total common stockholders' equity	4,535	4,253
Noncontrolling interests	37	37
Total equity	4,572	4,290
Total Liabilities and Equity	22,120	21,622
Consumers Energy Company [Member]
Current Assets
Cash and cash equivalents	55	131
Restricted cash and cash equivalents	27	19
Accounts receivable and accrued revenue, less allowance	612	800
Notes receivable, less allowance	30	29
Accounts receivable - related parties	2	9
Inventories at average cost
Gas in underground storage	584	446
Materials and supplies	121	114
Generating plant fuel stock	73	57
Deferred property taxes	157	250
Regulatory assets	19	17
Prepayments and other current assets	110	70
Total current assets	1,790	1,942
Plant, Property, and Equipment
Plant, property, and equipment, gross	21,784	20,838
Less accumulated depreciation and amortization	6,335	5,994
Plant, property, and equipment, net	15,449	14,844
Construction work in progress	877	759
Total plant, property, and equipment	16,326	15,603
Other Non-current Assets
Regulatory assets	2,038	2,091
Accounts and notes receivable	45	27
Investments	21	33
Other	160	250
Total other non-current assets	2,264	2,401
Total Assets	20,380	19,946
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation	464	397
Notes payable	230	398
Accounts payable	601	580
Accounts payable - related parties	12	18
Accrued rate refunds	35	21
Accrued interest	48	67
Accrued taxes	111	354
Regulatory liabilities	85	95
Other current liabilities	93	164
Total current liabilities	1,679	2,094
Non-current Liabilities
Long-term debt	5,275	5,253
Non-current portion of capital leases and financing obligation	97	110
Regulatory liabilities	2,066	2,041
Postretirement benefits	703	730
Asset retirement obligations	442	446
Deferred investment tax credit	88	73
Deferred income taxes	3,257	3,042
Other non-current liabilities	241	218
Total non-current liabilities	12,169	11,913
Commitments and Contingencies (Notes 2 and 3)
Common stockholder's equity
Common stock	841	841
Other paid-in capital	4,449	3,999
Accumulated other comprehensive loss	(8)	(3)
Retained earnings (Accumulated deficit)	1,213	1,065
Total common stockholders' equity	6,495	5,902
Preferred stock	37	37
Total equity	6,532	5,939
Total Liabilities and Equity	$ 20,380	$ 19,946

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Allowances for doubtful accounts receivable	$ 22	$ 24
Allowances for doubtful notes receivable	$ 19	$ 16
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares outstanding	281,600,000	279,200,000
Consumers Energy Company [Member]
Allowances for doubtful accounts receivable	$ 22	$ 24
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares outstanding	84,100,000	84,100,000

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Equity - USD ($) $ in Millions	Consumers Energy Company [Member]CMS Energy Common Stock [Member]	Consumers Energy Company [Member]Other Paid-in Capital [Member]	Consumers Energy Company [Member]Accumulated Other Comprehensive (Loss) [Member]	Consumers Energy Company [Member]Retirement Benefits Liability [Member]	Consumers Energy Company [Member]Investments [Member]	Consumers Energy Company [Member]Retained Earnings (Accumulated Deficit) [Member]	Consumers Energy Company [Member]Preferred Stock [Member]	Consumers Energy Company [Member]	CMS Energy Common Stock [Member]	Other Paid-in Capital [Member]	Accumulated Other Comprehensive (Loss) [Member]	Retirement Benefits Liability [Member]	Investments [Member]	Retained Earnings (Accumulated Deficit) [Member]	Noncontrolling Interest [Member]	Total
Cumulative effect of change in accounting principle														$ 33
Total Equity, beginning at Dec. 31, 2015	$ 841	$ 3,724	$ (6)	$ (19)	$ 13	$ 950	$ 37	$ 5,546	$ 3	$ 4,837	$ (47)	$ (43)	$ (4)	(855)	$ 37	$ 3,975
Common stock issued										82
Common stock repurchased										(11)
Common stock reissued
Stockholder contribution		275
Amortization of net actuarial loss												2				2
Amortization of prior service credit												(1)				(1)
Unrealized gain (loss) on investments					3			3					1			1
Reclassification adjustments included in net income, net of tax
Net income (loss) attributable to CMS Energy														474		474
Net Income						499		499								475
Dividends declared on common stock						(361)								(259)
Dividends declared on preferred stock						(1)
Income Attributable to Noncontrolling Interests															1	1
Distributions, and other changes in noncontrolling interests															(1)
Total Equity, end at Sep. 30, 2016	841	3,999	(3)	(19)	16	1,087	37	5,961	3	4,908	(45)	(42)	(3)	(607)	37	4,296
Total Equity, beginning at Jun. 30, 2016	841	3,999	(1)	(19)	18	1,040	37	5,916	3	4,906	(47)	(43)	(4)	(706)	37	4,193
Common stock issued										3
Common stock repurchased										(1)
Common stock reissued
Stockholder contribution
Amortization of net actuarial loss												1				1
Amortization of prior service credit
Unrealized gain (loss) on investments					(2)			(2)					1			1
Reclassification adjustments included in net income, net of tax
Net income (loss) attributable to CMS Energy														186		186
Net Income						195		195								186
Dividends declared on common stock						(148)								(87)
Distributions, and other changes in noncontrolling interests
Total Equity, end at Sep. 30, 2016	841	3,999	(3)	(19)	16	1,087	37	5,961	3	4,908	(45)	(42)	(3)	(607)	37	4,296
Total Equity, beginning at Dec. 31, 2016	841	3,999	(3)	(21)	18	1,065	37	5,939	3	4,916	(50)	(50)		(616)	37	4,290
Common stock issued										95
Common stock repurchased										(13)
Common stock reissued										15
Stockholder contribution		450
Amortization of net actuarial loss				1				1				1				1
Amortization of prior service credit
Unrealized gain (loss) on investments					2			2					2			2
Reclassification adjustments included in net income, net of tax					(8)			(8)
Net income (loss) attributable to CMS Energy														463		463
Net Income						496		496								464
Dividends declared on common stock						(347)								(281)
Dividends declared on preferred stock						(1)
Income Attributable to Noncontrolling Interests															1	1
Distributions, and other changes in noncontrolling interests															(1)
Total Equity, end at Sep. 30, 2017	841	4,449	(8)	(20)	12	1,213	37	6,532	3	5,013	(47)	(49)	2	(434)	37	4,572
Total Equity, beginning at Jun. 30, 2017	841	4,449	(8)	(20)	12	1,143	37	6,462	3	5,006	(48)	(49)	1	(512)	37	4,486
Common stock issued										7
Common stock repurchased
Common stock reissued
Stockholder contribution
Amortization of net actuarial loss
Amortization of prior service credit
Unrealized gain (loss) on investments													1			1
Reclassification adjustments included in net income, net of tax
Net income (loss) attributable to CMS Energy														172		172
Net Income						181		181								172
Dividends declared on common stock						(111)								(94)
Distributions, and other changes in noncontrolling interests
Total Equity, end at Sep. 30, 2017	$ 841	$ 4,449	$ (8)	$ (20)	$ 12	$ 1,213	$ 37	$ 6,532	$ 3	$ 5,013	$ (47)	$ (49)	$ 2	$ (434)	$ 37	$ 4,572

New Accounting Standards

New Accounting Standards	9 Months Ended
	Sep. 30, 2017
New Accounting Standards	1: New Accounting Standards Implementation of New Accounting Standards ASU 2017 ‑07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost: This standard was issued to improve the reporting of net benefit cost by employers that offer defined benefit pension plans and other postretirement benefit plans. The required effective date of the standard for CMS Energy and Consumers is January 1, 2018 , but early adoption was permitted in the first interim period of 2017. CMS Energy and Consumers elected to adopt the standard as of January 1, 2017. The standard requires employers to report the service cost component of net benefit cost in the same line item on the income statement as other employee compensation costs, while presenting the other cost components separately outside of operating income . This change is to be applied retrospectively to all prior periods presented. Accordingly, for the three months and nine months ended September 30, 2017 and 2016, CMS Energy and Consumers have presented the service cost component of their retirement benefits plans in maintenance and other operating expenses on the consolidated statements of income, while presenting the other components in n onoperating retirement benefits, net , under other income (expense). Prior to this standard, CMS Energy and Consumers had presented all of the cost components in maintenance and other operating expenses. Under a practical expedient permitted by the standard, CMS Energy and Consumers used benefit cost amounts disclosed for prior periods as the basis for retrospective application. In addition, under this standard, only the service cost component is eligible for capitalization as part of the cost of an asset . This change is to be appl ied prospectively upon adoption. Accordingly, for the three months and nine months ended September 30, 2017, CMS Energy and Consumers capitalized a portion of the service cost component of their retirement benefits plans to plant, property, and equipment, while recognizing the other components in net income. In prior periods, a portion of all cost components was capitalized . For further details on the net periodic cost of CMS Energy’s and Consumers’ retirement benefits plans, see Note 8, Retirement Benefits. The implementation of this standard did not have a material impact on CMS Energy’s or Consumers’ consolidated net income, cash flows, or financial position . New Accounting Standards Not Yet Effective ASU 2014 ‑09, Revenue from Contracts with Customers: This standard provides new guidance for recognizing revenue from contracts with customers. A primary objective of the standard is to provide a single, comprehensive revenue recognition model that will be applied across entities, industries, and capital markets. The new guidance will replace most of the existing revenue recognition requirements in GAAP, although certain guidance specific to rate-regulated utilities will be retained. The standard will be effective on January 1, 2018 for CMS Energy and Consumers, but early adoption in 2017 is permitted. Entities will have the option to apply the standard retrospectively to all prior periods presented, or to apply it retrospectively only to contracts existing at the effective date, with the cumulative effect of the standard recorded as an adjustment to beginning retained earnings. CMS Energy and Consumers are not adopting the standard early, and will apply the standard retrospectively only to contracts existing on the effective date, with the cumulative effect of the standard recorded as an adjustment to beginning retained earnings. CMS Energy and Consumers are continuing to evaluate the standard; however, they do not expect that it will have a material impact on their consolidated net income, cash flows, or financial position. CMS Energy and Consumers will provide additional disclosures about their revenues in accordance with the new standard, but they have not yet identified any significant changes in their revenue recognition practices that may be required. ASU 2016 ‑01, Recognition and Measurement of Financial Assets and Financial Liabilities: This standard, which will be effective January 1, 2018 for CMS Energy and Consumers, is intended to improve the accounting for financial instruments. The standard will require investments in equity securities to be measured at fair value, with changes in fair value recognized in net income, except for certain investments such as those that qualify for equity-method accounting. The standard will no longer permit unrealized gains and losses for certain equity investments to be recorded in AOCI. CMS Energy and Consumers presently record unrealized gains and losses on certain equity investments, including the mutual funds in the DB SERP and Consumers’ investment in CMS Energy common stock, in AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. For further details on these investments, see Note 6, Financial Instruments. Entities will apply the standard using a modified retrospective approach, with a cumulative-effect adjustment recorded to beginning retained earnings on the effective date. ASU 2016 ‑02, Leases: This standard establishes a new accounting model for leases. The standard will require entities to recognize lease assets and liabilities on the balance sheet for all leases with a term of more than one year, including operating leases, which are not recorded on the balance sheet under existing standards. As a result, CMS Energy and Consumers expect to recognize additional lease assets and liabilities for their operating leases under this standard. The new guidance will also amend the definition of a lease to require that a lessee control the use of a specified asset, and not simply control or take the output of the asset. On the income statement, leases that meet existing capital lease criteria will generally be accounted for under a financing model, while operating leases will generally be accounted for under a straight-line expense model. The standard will be effective on January 1, 2019 for CMS Energy and Consumers, but early adoption is permitted. CMS Energy and Consumers are continuing to evaluate the impact of the standard on their consolidated financial statements and do not presently expect to adopt the standard early. ASU 2016 ‑13, Measurement of Credit Losses on Financial Instruments: This standard, which will be effective January 1, 2020 for CMS Energy and Consumers, provides new guidance for estimating and recording credit losses on financial instruments. The standard will apply to the recognition of loan losses at EnerBank as well as to the recognition of uncollectible accounts expense at Consumers. Entities will apply the standard using a modified retrospective approach, with a cumulative-effect adjustment recorded to beginning retained earnings on the effective date. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements.
Consumers Energy Company [Member]
New Accounting Standards	1: New Accounting Standards Implementation of New Accounting Standards ASU 2017 ‑07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost: This standard was issued to improve the reporting of net benefit cost by employers that offer defined benefit pension plans and other postretirement benefit plans. The required effective date of the standard for CMS Energy and Consumers is January 1, 2018 , but early adoption was permitted in the first interim period of 2017. CMS Energy and Consumers elected to adopt the standard as of January 1, 2017. The standard requires employers to report the service cost component of net benefit cost in the same line item on the income statement as other employee compensation costs, while presenting the other cost components separately outside of operating income . This change is to be applied retrospectively to all prior periods presented. Accordingly, for the three months and nine months ended September 30, 2017 and 2016, CMS Energy and Consumers have presented the service cost component of their retirement benefits plans in maintenance and other operating expenses on the consolidated statements of income, while presenting the other components in n onoperating retirement benefits, net , under other income (expense). Prior to this standard, CMS Energy and Consumers had presented all of the cost components in maintenance and other operating expenses. Under a practical expedient permitted by the standard, CMS Energy and Consumers used benefit cost amounts disclosed for prior periods as the basis for retrospective application. In addition, under this standard, only the service cost component is eligible for capitalization as part of the cost of an asset . This change is to be appl ied prospectively upon adoption. Accordingly, for the three months and nine months ended September 30, 2017, CMS Energy and Consumers capitalized a portion of the service cost component of their retirement benefits plans to plant, property, and equipment, while recognizing the other components in net income. In prior periods, a portion of all cost components was capitalized . For further details on the net periodic cost of CMS Energy’s and Consumers’ retirement benefits plans, see Note 8, Retirement Benefits. The implementation of this standard did not have a material impact on CMS Energy’s or Consumers’ consolidated net income, cash flows, or financial position . New Accounting Standards Not Yet Effective ASU 2014 ‑09, Revenue from Contracts with Customers: This standard provides new guidance for recognizing revenue from contracts with customers. A primary objective of the standard is to provide a single, comprehensive revenue recognition model that will be applied across entities, industries, and capital markets. The new guidance will replace most of the existing revenue recognition requirements in GAAP, although certain guidance specific to rate-regulated utilities will be retained. The standard will be effective on January 1, 2018 for CMS Energy and Consumers, but early adoption in 2017 is permitted. Entities will have the option to apply the standard retrospectively to all prior periods presented, or to apply it retrospectively only to contracts existing at the effective date, with the cumulative effect of the standard recorded as an adjustment to beginning retained earnings. CMS Energy and Consumers are not adopting the standard early, and will apply the standard retrospectively only to contracts existing on the effective date, with the cumulative effect of the standard recorded as an adjustment to beginning retained earnings. CMS Energy and Consumers are continuing to evaluate the standard; however, they do not expect that it will have a material impact on their consolidated net income, cash flows, or financial position. CMS Energy and Consumers will provide additional disclosures about their revenues in accordance with the new standard, but they have not yet identified any significant changes in their revenue recognition practices that may be required. ASU 2016 ‑01, Recognition and Measurement of Financial Assets and Financial Liabilities: This standard, which will be effective January 1, 2018 for CMS Energy and Consumers, is intended to improve the accounting for financial instruments. The standard will require investments in equity securities to be measured at fair value, with changes in fair value recognized in net income, except for certain investments such as those that qualify for equity-method accounting. The standard will no longer permit unrealized gains and losses for certain equity investments to be recorded in AOCI. CMS Energy and Consumers presently record unrealized gains and losses on certain equity investments, including the mutual funds in the DB SERP and Consumers’ investment in CMS Energy common stock, in AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. For further details on these investments, see Note 6, Financial Instruments. Entities will apply the standard using a modified retrospective approach, with a cumulative-effect adjustment recorded to beginning retained earnings on the effective date. ASU 2016 ‑02, Leases: This standard establishes a new accounting model for leases. The standard will require entities to recognize lease assets and liabilities on the balance sheet for all leases with a term of more than one year, including operating leases, which are not recorded on the balance sheet under existing standards. As a result, CMS Energy and Consumers expect to recognize additional lease assets and liabilities for their operating leases under this standard. The new guidance will also amend the definition of a lease to require that a lessee control the use of a specified asset, and not simply control or take the output of the asset. On the income statement, leases that meet existing capital lease criteria will generally be accounted for under a financing model, while operating leases will generally be accounted for under a straight-line expense model. The standard will be effective on January 1, 2019 for CMS Energy and Consumers, but early adoption is permitted. CMS Energy and Consumers are continuing to evaluate the impact of the standard on their consolidated financial statements and do not presently expect to adopt the standard early. ASU 2016 ‑13, Measurement of Credit Losses on Financial Instruments: This standard, which will be effective January 1, 2020 for CMS Energy and Consumers, provides new guidance for estimating and recording credit losses on financial instruments. The standard will apply to the recognition of loan losses at EnerBank as well as to the recognition of uncollectible accounts expense at Consumers. Entities will apply the standard using a modified retrospective approach, with a cumulative-effect adjustment recorded to beginning retained earnings on the effective date. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2017
Regulatory Matters	2: Regulatory Matters Regulatory matters are critical to Consumers. The Michigan Attorney General, ABATE, the MPSC Staff, and certain other parties typically participate in MPSC proceedings concerning Consumers, such as Consumers’ rate cases and PSCR and GCR processes. These parties often challenge various aspects of those proceedings, including the prudence of Consumers’ policies and practices, and seek cost disallowances and other relief. The parties also have appealed significant MPSC orders. Depending upon the specific issues, the outcomes of rate cases and proceedings, including judicial proceedings challenging MPSC orders or other actions, could negatively affect CMS Energy’s and Consumers’ liquidity, financial condition, and results of operations. Consumers cannot predict the outcome of these proceedings. There are multiple appeals pending that involve various issues concerning cost recovery from customers, the adequacy of the record evidence supporting the recovery of Smart Energy investments, and other matters. Consumers is unable to predict the outcome of these appeals. Electric Rate Case: In March 2016, Consumers filed an application with the MPSC seeking an annual rate increase of $225 million, based on a 10.7 percent authorized return on equity. In September 2016, Consumers self ‑implemented an annual rate increase of $170 million, subject to refund with interest. The MPSC issued an order in February 2017, authorizing an annual rate increase of $113 million, based on a 10.1 percent authorized return on equity. In May 2017, Consumers filed a reconciliation of total revenues collected during self-implementation to those that would have been collected under final rates. The reconciliation indicated that a refund would be required, and Consumers had a $17 million recorded reserve for customer refunds at September 3 0 , 2017. In October 2017, the MPSC approved a settlement agreement that will result in a $17 million refund to customers during December 2017. Gas Rate Case: In August 2016, Consumers filed an application with the MPSC seeking an annual rate increase of $90 million, based on a 10.6 percent authorized return on equity. Consumers later reduced its requested annual rate increase to $80 million. I n January 2017, Consumers self-implemented an annual rate increase of $20 million . The MPSC issued an order in July 2017, authorizing an annual rate increase of $29 million beginning in August 2017. The MPSC also approved an investment recovery mechanism that will provide for additional annual rate increases of $18 million beginning in 2018 and another $18 million beginning in 2019 for incremental investments that Consumers plans to make in those years, subject to reconciliation. These future investments are intended to help ensure adequate system capacity, deliverability, and safety. The investment recovery surcharge will remain in effect until rates are reset in a subsequent general rate case. Energy Optimization Plan Incentive: In September 2017, the MPSC approved a settlement agreement authorizing Consumers to collect $18 million during 2018 as an incentive for exceeding its statutory savings targets in 2016. Consumers recognized incentive revenue under this program of $18 million in 2016. Depreciation Rate Case: In August 2016, Consumers filed a depreciation rate case related to its gas utility property, requesting to decrease depreciation expense by $3 million annually. In March 2017, the MPSC approved a settlement agreement authorizing the requested decrease in depreciation expense effective as of January 2017 . FERC Transmission Order: In September 2016, FERC issued an order reducing the rate of return on equity earned by transmission owners operating within MISO to a base of 10.32 percent from 12.38 percent. FERC ordered MISO and transmission owners to provide refunds, with interest, to transmission customers such as Consumers for the period from November 2013 through February 2015. In February 2017, as a result of this order, Consumers received from MISO a credit of $28 million, which it will return to its electric customers through the PSCR ratemaking process. The FERC order is subject to further legal proceedings and Consumers’ MISO credit may be adjusted accordingly .
Consumers Energy Company [Member]
Regulatory Matters	2: Regulatory Matters Regulatory matters are critical to Consumers. The Michigan Attorney General, ABATE, the MPSC Staff, and certain other parties typically participate in MPSC proceedings concerning Consumers, such as Consumers’ rate cases and PSCR and GCR processes. These parties often challenge various aspects of those proceedings, including the prudence of Consumers’ policies and practices, and seek cost disallowances and other relief. The parties also have appealed significant MPSC orders. Depending upon the specific issues, the outcomes of rate cases and proceedings, including judicial proceedings challenging MPSC orders or other actions, could negatively affect CMS Energy’s and Consumers’ liquidity, financial condition, and results of operations. Consumers cannot predict the outcome of these proceedings. There are multiple appeals pending that involve various issues concerning cost recovery from customers, the adequacy of the record evidence supporting the recovery of Smart Energy investments, and other matters. Consumers is unable to predict the outcome of these appeals. Electric Rate Case: In March 2016, Consumers filed an application with the MPSC seeking an annual rate increase of $225 million, based on a 10.7 percent authorized return on equity. In September 2016, Consumers self ‑implemented an annual rate increase of $170 million, subject to refund with interest. The MPSC issued an order in February 2017, authorizing an annual rate increase of $113 million, based on a 10.1 percent authorized return on equity. In May 2017, Consumers filed a reconciliation of total revenues collected during self-implementation to those that would have been collected under final rates. The reconciliation indicated that a refund would be required, and Consumers had a $17 million recorded reserve for customer refunds at September 3 0 , 2017. In October 2017, the MPSC approved a settlement agreement that will result in a $17 million refund to customers during December 2017. Gas Rate Case: In August 2016, Consumers filed an application with the MPSC seeking an annual rate increase of $90 million, based on a 10.6 percent authorized return on equity. Consumers later reduced its requested annual rate increase to $80 million. I n January 2017, Consumers self-implemented an annual rate increase of $20 million . The MPSC issued an order in July 2017, authorizing an annual rate increase of $29 million beginning in August 2017. The MPSC also approved an investment recovery mechanism that will provide for additional annual rate increases of $18 million beginning in 2018 and another $18 million beginning in 2019 for incremental investments that Consumers plans to make in those years, subject to reconciliation. These future investments are intended to help ensure adequate system capacity, deliverability, and safety. The investment recovery surcharge will remain in effect until rates are reset in a subsequent general rate case. Energy Optimization Plan Incentive: In September 2017, the MPSC approved a settlement agreement authorizing Consumers to collect $18 million during 2018 as an incentive for exceeding its statutory savings targets in 2016. Consumers recognized incentive revenue under this program of $18 million in 2016. Depreciation Rate Case: In August 2016, Consumers filed a depreciation rate case related to its gas utility property, requesting to decrease depreciation expense by $3 million annually. In March 2017, the MPSC approved a settlement agreement authorizing the requested decrease in depreciation expense effective as of January 2017 . FERC Transmission Order: In September 2016, FERC issued an order reducing the rate of return on equity earned by transmission owners operating within MISO to a base of 10.32 percent from 12.38 percent. FERC ordered MISO and transmission owners to provide refunds, with interest, to transmission customers such as Consumers for the period from November 2013 through February 2015. In February 2017, as a result of this order, Consumers received from MISO a credit of $28 million, which it will return to its electric customers through the PSCR ratemaking process. The FERC order is subject to further legal proceedings and Consumers’ MISO credit may be adjusted accordingly .

Contingencies And Commitments

Contingencies And Commitments	9 Months Ended
	Sep. 30, 2017
Contingencies And Commitments	3 : Contingencies and Commitments CMS Energy and Consumers are involved in various matters that give rise to contingent liabilities. Depending on the specific issues, the resolution of these contingencies could negatively affect CMS Energy’s and Consumers’ liquidity, financial condition, and results of operations. In their disclosures of these matters, CMS Energy and Consumers provide an estimate of the possible loss or range of loss when such an estimate can be made. Disclosures that state that CMS Energy or Consumers cannot predict the outcome of a matter indicate that they are unable to estimate a possible loss or range of loss for the matter. CMS Energy Contingencies Gas Index Price Reporting Litigation: CMS Energy, along with CMS MST, CMS Field Services, Cantera Natural Gas, Inc., and Cantera Gas Company, have been named as defendants in four class action lawsuits and one individual lawsuit arising as a result of alleged inaccurate natural gas price reporting to publications that report trade information. Allegations include price-fixing conspiracies, restraint of trade, and artificial inflation of natural gas retail prices in Kansas, Missouri, and Wisconsin. Plaintiffs are making claims for the following: treble damages, full consideration damages, exemplary damages, costs, interest, and/or attorneys’ fees. After removal to federal court, all of the cases were transferred to a single federal district court pursuant to the multidistrict litigation process. In 2010 and 2011, all claims against CMS Energy defendants were dismissed by the district court based on FERC preemption. In 2013, the U.S. Court of Appeals for the Ninth Circuit reversed the district court decision. The appellate court found that FERC preemption does not apply under the facts of these cases. The appellate court affirmed the district court’s denial of leave to amend to add federal antitrust claims. The matter was appealed to the U.S. Supreme Court, which in 2015 upheld the Ninth Circuit’s decision. The cases were remanded back to the federal district court. In May 2016, the federal district court granted the defendants’ motion for summary judgment in the individual lawsuit based on a release in a prior settlement involving similar allegations and reinstated CMS Energy as a defendant in one of the class action lawsuits. The order of summary judgment has been appealed. In December 2016, CMS Energy entities reached a settlement with the plaintiffs in the three Kansas and Missouri cases for an amount that was not material to CMS Energy. In August 2017, t he federal district court approved the settlement . CMS Energy entities remain as defendants in the Wisconsin class action lawsuits. In March 2017, the federal district court denied plaintiffs’ motion for class certification. The plaintiffs app ealed that decision to the U.S. Court of Appeals for the Ninth Circuit, which has accepted the matter for hearing. In June 2017, an unaffiliated company that is also a defendant in these cases filed for bankruptcy, which could increase the risk of loss to CMS Energy. These cases involve complex facts, a large number of similarly situated defendants with different factual positions, and multiple jurisdictions. Presently, any estimate of liability would be highly speculative; the amount of CMS Energy’s reasonably possible loss would be based on widely varying models previously untested in this context. If the outcome after appeals is unfavorable, these cases could negatively affect CMS Energy’s liquidity, financial condition, and results of operations. Bay Harbor: CMS Land retained environmental remediation obligations for the collection and treatment of leachate, a liquid consisting of water and other substances, at Bay Harbor after selling its interests in the development in 2002. Leachate is produced when water enters into cement kiln dust piles left over from former cement plant operations at the site. In 2012, CMS Land and the MDEQ finalized an agreement that established the final remedies and the future water quality criteria at the site. CMS Land completed all construction necessary to implement the remedies required by the agreement and will continue to maintain and operate a system to discharge treated leachate into Little Traverse Bay under an NPDES permit issued in 2010 and renewed in October 2016. The renewed NPDES permit is valid through September 2020. Various claims have been brought against CMS Land or its affiliates, including CMS Energy, alleging environmental damage to property, loss of property value, insufficient disclosure of environmental matters, breach of agreement relating to access, or other matters. CMS Land and other parties have received a demand for payment from the EPA in the amount of $ 8 million, plus interest. The EPA is seeking recovery under CERCLA of response costs allegedly incurred at Bay Harbor. These costs exceed what was agreed to in a 2005 order between CMS Land and the EPA, and CMS Land has communicated to the EPA that it does not believe that this is a valid claim. The EPA has filed a lawsuit to collect these costs. At September 30, 2017, CMS Energy had a recorded liability of $49 million for its remaining obligations for environmental remediation. CMS Energy calculated this liability based on discounted projected costs, using a discount rate of 4.34 percent and an inflation rate of one percent on annual operating and maintenance costs. The undiscounted amount of the remaining obligation is $62 million. CMS Energy expects to pay the following amounts for long-term liquid disposal and operating and maintenance costs during the remainder of 2017 and in each of the next five years:    In Millions  2017 2018 2019 2020 2021 2022  CMS Energy  Long-term liquid disposal and operating and maintenance costs $ 1 $ 4 $ 4 $ 4 $ 4 $ 4  CMS Energy’s estimate of response activity costs and the timing of expenditures could change if there are changes in circumstances or assumptions used in calculating the liability. Although a liability for its present estimate of remaining response activity costs has been recorded, CMS Energy cannot predict the ultimate financial impact or outcome of this matter. Equatorial Guinea Tax Claim: In 2002, CMS Energy sold its oil, gas, and methanol investments in Equatorial Guinea. The government of Equatorial Guinea claims that, in connection with the sale, CMS Energy owes $ 152 million in taxes, plus substantial penalties and interest that could be up to the amount of the taxes claimed. The matter is proceeding to formal arbitration. CMS Energy has concluded that the government’s tax claim is without merit and is contesting the claim, but cannot predict the financial impact or outcome of the matter. An unfavorable outcome could have a material adverse effect on CMS Energy’s liquidity, financial condition, and results of operations. Consumers Electric Utility Contingencies Electric Environmental Matters: Consumers’ operations are subject to environmental laws and regulations. Historically, Consumers has generally been able to recover, in customer rates, the costs to operate its facilities in compliance with these laws and regulations. Cleanup and Solid Waste: Consumers expects to incur remediation and other response activity costs at a number of sites under the NREPA. Consumers believes that these costs should be recoverable in rates, but cannot guarantee that outcome. Consumers estimates that its liability for NREPA sites for which it can estimate a range of loss will be between $ 3 million and $ 4 million. At September 30, 2017, Consumers had a recorded liability of $ 3 million, the minimum amount in the range of its estimated probable NREPA liability, as no amount in the range was considered a better estimate than any other amount. Consumers is a potentially responsible party at a number of contaminated sites administered under CERCLA. CERCLA liability is joint and several. In 2010, Consumers received official notification from the EPA that identified Consumers as a potentially responsible party for cleanup of PCBs at the Kalamazoo River CERCLA site. The notification claimed that the EPA has reason to believe that Consumers disposed of PCBs and arranged for the disposal and treatment of PCB-containing materials at portions of the site. In 2011, Consumers received a follow ‑up letter from the EPA requesting that Consumers agree to participate in a removal action plan along with several other companies for an area of lower Portage Creek, which is connected to the Kalamazoo River. All parties, including Consumers, that were asked to participate in the removal action plan declined to accept liability. Until further information is received from the EPA, Consumers is unable to estimate a range of potential liability for cleanup of the river. Based on its experience, Consumers estimates that its share of the total liability for known CERCLA sites will be between $ 3 million and $ 8 million. Various factors, including the number and creditworthiness of potentially responsible parties involved with each site, affect Consumers’ share of the total liability. At September 30, 2017, Consumers had a recorded liability of $ 3 million for its share of the total liability at these sites, the minimum amount in the range of its estimated probable CERCLA liability, as no amount in the range was considered a better estimate than any other amount. The timing of payments related to Consumers’ remediation and other response activities at its CERCLA and NREPA sites is uncertain. Consumers periodically reviews these cost estimates. A change in the underlying assumptions, such as an increase in the number of sites, different remediation techniques, the nature and extent of contamination, and legal and regulatory requirements, could affect its estimates of NREPA and CERCLA liability. Ludington PCB: In 1998, during routine maintenance activities, Consumers identified PCB as a component in certain paint, grout, and sealant materials at Ludington. Consumers removed part of the PCB material and replaced it with non ‑PCB material. Consumers has had several communications with the EPA regarding this matter, but cannot predict the financial impact or outcome. Consumers Gas Utility Contingencies Gas Environmental Matters: Consumers expects to incur remediation and other response activity costs at a number of sites under the NREPA. These sites include 23 former MGP facilities. Consumers operated the facilities on these sites for some part of their operating lives. For some of these sites, Consumers has no present ownership interest or may own only a portion of the original site. At September 30, 2017, Consumers had a recorded liability of $ 93 million for its remaining obligations for these sites. This amount represents the present value of long-term projected costs, using a discount rate of 2.57 percent and an inflation rate of 2.5 percent. The undiscounted amount of the remaining obligation is $ 104 million. Consumers expects to pay the following amounts for remediation and other response activity costs during the remainder of 2017 and in each of the next five years:    In Millions  2017 2018 2019 2020 2021 2022  Consumers  Remediation and other response activity costs $ 8 $ 16 $ 18 $ 10 $ 18 $ 7  Consumers periodically reviews these cost estimates. Any significant change in the underlying assumptions, such as an increase in the number of sites, changes in remediation techniques, or legal and regulatory requirements, could affect Consumers’ estimates of annual response activity costs and the MGP liability. Pursuant to orders issued by the MPSC, Consumers defers its MGP-related remediation costs and recovers them from its customers over a ten ‑year period. At September 30, 2017, Consumers had a regulatory asset of $ 141 million related to the MGP sites. Consumers estimates that its liability to perform remediation and other response activities at NREPA sites other than the MGP sites could reach $3 million. At September 30, 2017, Consumers had a recorded liability of less than $1 million, the minimum amount in the range of its estimated probable liability, as no amount in the range was considered a better estimate than any other amount. Guarantees Presented in the following table are CMS Energy’s a nd Consumers’ guarantees at September 30, 2017:    In Millions  Maximum Carrying  Guarantee Description Issue Date Expiration Date Obligation Amount  CMS Energy, including Consumers  Indemnity obligations from stock and asset sale agreements 1 Various Indefinite $ 153 $ 7  Guarantees 2 Various Indefinite 45 -  Consumers  Guarantee 2 July 2011 Indefinite $ 30 $ -  1 These obligations arose from stock and asset sale agreements under which CMS Energy or a subsidiary of CMS Energy indemnified the purchaser for losses resulting from various matters, primarily claims related to taxes. CMS Energy believes the likelihood of material loss to be remote for the indemnity obligations not recorded as liabilities. 2 At Consumers, this obligation comprises a guarantee provided to the U.S. Department of Energy in connection with a settlement agreement regarding damages resulting from the department’s failure to accept spent nuclear fuel from nuclear power plants formerly owned by Consumers. At CMS Energy, the guarantee obligations comprise Consumers’ guarantee to the U.S. Department of Energy and CMS Energy’s 1994 guarantee of non-recourse revenue bonds issued by Genesee. Additionally, in the normal course of business, CMS Energy, Consumers, and certain other subsidiaries of CMS Energy have entered into various agreements containing tax and other indemnity provisions for which they are unable to estimate the maximum potential obligation. The carrying value of these indemnity obligations is $1 million. CMS Energy and Consumers consider the likelihood that they would be required to perform or incur substantial losses related to these indemnities to be remote. Other Contingencies In addition to the matters disclosed in this Note and Note 2, Regulatory Matters, there are certain other lawsuits and administrative proceedings before various courts and governmental agencies arising in the ordinary course of business to which CMS Energy, Consumers, and certain other subsidiaries of CMS Energy are parties. These other lawsuits and proceedings may involve personal injury, property damage, contracts, environmental matters, federal and state taxes, rates, licensing, employment, and other matters. Further, CMS Energy and Consumers occasionally self-report certain regulatory non ‑compliance matters that may or may not eventually result in administrative proceedings. CMS Energy and Consumers believe that the outcome of any one of these proceedings will not have a material negative effect on their consolidated results of operations, financial condition, or liquidity.
Consumers Energy Company [Member]
Contingencies And Commitments	3 : Contingencies and Commitments CMS Energy and Consumers are involved in various matters that give rise to contingent liabilities. Depending on the specific issues, the resolution of these contingencies could negatively affect CMS Energy’s and Consumers’ liquidity, financial condition, and results of operations. In their disclosures of these matters, CMS Energy and Consumers provide an estimate of the possible loss or range of loss when such an estimate can be made. Disclosures that state that CMS Energy or Consumers cannot predict the outcome of a matter indicate that they are unable to estimate a possible loss or range of loss for the matter. CMS Energy Contingencies Gas Index Price Reporting Litigation: CMS Energy, along with CMS MST, CMS Field Services, Cantera Natural Gas, Inc., and Cantera Gas Company, have been named as defendants in four class action lawsuits and one individual lawsuit arising as a result of alleged inaccurate natural gas price reporting to publications that report trade information. Allegations include price-fixing conspiracies, restraint of trade, and artificial inflation of natural gas retail prices in Kansas, Missouri, and Wisconsin. Plaintiffs are making claims for the following: treble damages, full consideration damages, exemplary damages, costs, interest, and/or attorneys’ fees. After removal to federal court, all of the cases were transferred to a single federal district court pursuant to the multidistrict litigation process. In 2010 and 2011, all claims against CMS Energy defendants were dismissed by the district court based on FERC preemption. In 2013, the U.S. Court of Appeals for the Ninth Circuit reversed the district court decision. The appellate court found that FERC preemption does not apply under the facts of these cases. The appellate court affirmed the district court’s denial of leave to amend to add federal antitrust claims. The matter was appealed to the U.S. Supreme Court, which in 2015 upheld the Ninth Circuit’s decision. The cases were remanded back to the federal district court. In May 2016, the federal district court granted the defendants’ motion for summary judgment in the individual lawsuit based on a release in a prior settlement involving similar allegations and reinstated CMS Energy as a defendant in one of the class action lawsuits. The order of summary judgment has been appealed. In December 2016, CMS Energy entities reached a settlement with the plaintiffs in the three Kansas and Missouri cases for an amount that was not material to CMS Energy. In August 2017, t he federal district court approved the settlement . CMS Energy entities remain as defendants in the Wisconsin class action lawsuits. In March 2017, the federal district court denied plaintiffs’ motion for class certification. The plaintiffs app ealed that decision to the U.S. Court of Appeals for the Ninth Circuit, which has accepted the matter for hearing. In June 2017, an unaffiliated company that is also a defendant in these cases filed for bankruptcy, which could increase the risk of loss to CMS Energy. These cases involve complex facts, a large number of similarly situated defendants with different factual positions, and multiple jurisdictions. Presently, any estimate of liability would be highly speculative; the amount of CMS Energy’s reasonably possible loss would be based on widely varying models previously untested in this context. If the outcome after appeals is unfavorable, these cases could negatively affect CMS Energy’s liquidity, financial condition, and results of operations. Bay Harbor: CMS Land retained environmental remediation obligations for the collection and treatment of leachate, a liquid consisting of water and other substances, at Bay Harbor after selling its interests in the development in 2002. Leachate is produced when water enters into cement kiln dust piles left over from former cement plant operations at the site. In 2012, CMS Land and the MDEQ finalized an agreement that established the final remedies and the future water quality criteria at the site. CMS Land completed all construction necessary to implement the remedies required by the agreement and will continue to maintain and operate a system to discharge treated leachate into Little Traverse Bay under an NPDES permit issued in 2010 and renewed in October 2016. The renewed NPDES permit is valid through September 2020. Various claims have been brought against CMS Land or its affiliates, including CMS Energy, alleging environmental damage to property, loss of property value, insufficient disclosure of environmental matters, breach of agreement relating to access, or other matters. CMS Land and other parties have received a demand for payment from the EPA in the amount of $ 8 million, plus interest. The EPA is seeking recovery under CERCLA of response costs allegedly incurred at Bay Harbor. These costs exceed what was agreed to in a 2005 order between CMS Land and the EPA, and CMS Land has communicated to the EPA that it does not believe that this is a valid claim. The EPA has filed a lawsuit to collect these costs. At September 30, 2017, CMS Energy had a recorded liability of $49 million for its remaining obligations for environmental remediation. CMS Energy calculated this liability based on discounted projected costs, using a discount rate of 4.34 percent and an inflation rate of one percent on annual operating and maintenance costs. The undiscounted amount of the remaining obligation is $62 million. CMS Energy expects to pay the following amounts for long-term liquid disposal and operating and maintenance costs during the remainder of 2017 and in each of the next five years:    In Millions  2017 2018 2019 2020 2021 2022  CMS Energy  Long-term liquid disposal and operating and maintenance costs $ 1 $ 4 $ 4 $ 4 $ 4 $ 4  CMS Energy’s estimate of response activity costs and the timing of expenditures could change if there are changes in circumstances or assumptions used in calculating the liability. Although a liability for its present estimate of remaining response activity costs has been recorded, CMS Energy cannot predict the ultimate financial impact or outcome of this matter. Equatorial Guinea Tax Claim: In 2002, CMS Energy sold its oil, gas, and methanol investments in Equatorial Guinea. The government of Equatorial Guinea claims that, in connection with the sale, CMS Energy owes $ 152 million in taxes, plus substantial penalties and interest that could be up to the amount of the taxes claimed. The matter is proceeding to formal arbitration. CMS Energy has concluded that the government’s tax claim is without merit and is contesting the claim, but cannot predict the financial impact or outcome of the matter. An unfavorable outcome could have a material adverse effect on CMS Energy’s liquidity, financial condition, and results of operations. Consumers Electric Utility Contingencies Electric Environmental Matters: Consumers’ operations are subject to environmental laws and regulations. Historically, Consumers has generally been able to recover, in customer rates, the costs to operate its facilities in compliance with these laws and regulations. Cleanup and Solid Waste: Consumers expects to incur remediation and other response activity costs at a number of sites under the NREPA. Consumers believes that these costs should be recoverable in rates, but cannot guarantee that outcome. Consumers estimates that its liability for NREPA sites for which it can estimate a range of loss will be between $ 3 million and $ 4 million. At September 30, 2017, Consumers had a recorded liability of $ 3 million, the minimum amount in the range of its estimated probable NREPA liability, as no amount in the range was considered a better estimate than any other amount. Consumers is a potentially responsible party at a number of contaminated sites administered under CERCLA. CERCLA liability is joint and several. In 2010, Consumers received official notification from the EPA that identified Consumers as a potentially responsible party for cleanup of PCBs at the Kalamazoo River CERCLA site. The notification claimed that the EPA has reason to believe that Consumers disposed of PCBs and arranged for the disposal and treatment of PCB-containing materials at portions of the site. In 2011, Consumers received a follow ‑up letter from the EPA requesting that Consumers agree to participate in a removal action plan along with several other companies for an area of lower Portage Creek, which is connected to the Kalamazoo River. All parties, including Consumers, that were asked to participate in the removal action plan declined to accept liability. Until further information is received from the EPA, Consumers is unable to estimate a range of potential liability for cleanup of the river. Based on its experience, Consumers estimates that its share of the total liability for known CERCLA sites will be between $ 3 million and $ 8 million. Various factors, including the number and creditworthiness of potentially responsible parties involved with each site, affect Consumers’ share of the total liability. At September 30, 2017, Consumers had a recorded liability of $ 3 million for its share of the total liability at these sites, the minimum amount in the range of its estimated probable CERCLA liability, as no amount in the range was considered a better estimate than any other amount. The timing of payments related to Consumers’ remediation and other response activities at its CERCLA and NREPA sites is uncertain. Consumers periodically reviews these cost estimates. A change in the underlying assumptions, such as an increase in the number of sites, different remediation techniques, the nature and extent of contamination, and legal and regulatory requirements, could affect its estimates of NREPA and CERCLA liability. Ludington PCB: In 1998, during routine maintenance activities, Consumers identified PCB as a component in certain paint, grout, and sealant materials at Ludington. Consumers removed part of the PCB material and replaced it with non ‑PCB material. Consumers has had several communications with the EPA regarding this matter, but cannot predict the financial impact or outcome. Consumers Gas Utility Contingencies Gas Environmental Matters: Consumers expects to incur remediation and other response activity costs at a number of sites under the NREPA. These sites include 23 former MGP facilities. Consumers operated the facilities on these sites for some part of their operating lives. For some of these sites, Consumers has no present ownership interest or may own only a portion of the original site. At September 30, 2017, Consumers had a recorded liability of $ 93 million for its remaining obligations for these sites. This amount represents the present value of long-term projected costs, using a discount rate of 2.57 percent and an inflation rate of 2.5 percent. The undiscounted amount of the remaining obligation is $ 104 million. Consumers expects to pay the following amounts for remediation and other response activity costs during the remainder of 2017 and in each of the next five years:    In Millions  2017 2018 2019 2020 2021 2022  Consumers  Remediation and other response activity costs $ 8 $ 16 $ 18 $ 10 $ 18 $ 7  Consumers periodically reviews these cost estimates. Any significant change in the underlying assumptions, such as an increase in the number of sites, changes in remediation techniques, or legal and regulatory requirements, could affect Consumers’ estimates of annual response activity costs and the MGP liability. Pursuant to orders issued by the MPSC, Consumers defers its MGP-related remediation costs and recovers them from its customers over a ten ‑year period. At September 30, 2017, Consumers had a regulatory asset of $ 141 million related to the MGP sites. Consumers estimates that its liability to perform remediation and other response activities at NREPA sites other than the MGP sites could reach $3 million. At September 30, 2017, Consumers had a recorded liability of less than $1 million, the minimum amount in the range of its estimated probable liability, as no amount in the range was considered a better estimate than any other amount. Guarantees Presented in the following table are CMS Energy’s a nd Consumers’ guarantees at September 30, 2017:    In Millions  Maximum Carrying  Guarantee Description Issue Date Expiration Date Obligation Amount  CMS Energy, including Consumers  Indemnity obligations from stock and asset sale agreements 1 Various Indefinite $ 153 $ 7  Guarantees 2 Various Indefinite 45 -  Consumers  Guarantee 2 July 2011 Indefinite $ 30 $ -  1 These obligations arose from stock and asset sale agreements under which CMS Energy or a subsidiary of CMS Energy indemnified the purchaser for losses resulting from various matters, primarily claims related to taxes. CMS Energy believes the likelihood of material loss to be remote for the indemnity obligations not recorded as liabilities. 2 At Consumers, this obligation comprises a guarantee provided to the U.S. Department of Energy in connection with a settlement agreement regarding damages resulting from the department’s failure to accept spent nuclear fuel from nuclear power plants formerly owned by Consumers. At CMS Energy, the guarantee obligations comprise Consumers’ guarantee to the U.S. Department of Energy and CMS Energy’s 1994 guarantee of non-recourse revenue bonds issued by Genesee. Additionally, in the normal course of business, CMS Energy, Consumers, and certain other subsidiaries of CMS Energy have entered into various agreements containing tax and other indemnity provisions for which they are unable to estimate the maximum potential obligation. The carrying value of these indemnity obligations is $1 million. CMS Energy and Consumers consider the likelihood that they would be required to perform or incur substantial losses related to these indemnities to be remote. Other Contingencies In addition to the matters disclosed in this Note and Note 2, Regulatory Matters, there are certain other lawsuits and administrative proceedings before various courts and governmental agencies arising in the ordinary course of business to which CMS Energy, Consumers, and certain other subsidiaries of CMS Energy are parties. These other lawsuits and proceedings may involve personal injury, property damage, contracts, environmental matters, federal and state taxes, rates, licensing, employment, and other matters. Further, CMS Energy and Consumers occasionally self-report certain regulatory non ‑compliance matters that may or may not eventually result in administrative proceedings. CMS Energy and Consumers believe that the outcome of any one of these proceedings will not have a material negative effect on their consolidated results of operations, financial condition, or liquidity.

Financings And Capitalization

Financings And Capitalization	9 Months Ended
	Sep. 30, 2017
Financings And Capitalization	4: Financings and Capitalization Financings: Presented in the following table is a summary of major long-term debt transactions during the nine months ended September 30, 2 017 .    Principal (In Millions) Interest Rate Issue/Retirement Date Maturity Date  Debt issuances  CMS Energy, parent only  Senior notes $ 350 3.450 % February 2017 August 2027  Total CMS Energy, parent only $ 350  Consumers  First mortgage bonds $ 350 3.950 % February 2017 July 2047  First mortgage bonds 1 40 3.180 September 2017 September 2032  First mortgage bonds 1 125 3.520 September 2017 September 2037  First mortgage bonds 1 20 3.860 September 2017 September 2052  Total Consumers $ 535  Total CMS Energy $ 885  Debt retirements  Consumers  First mortgage bonds $ 250 5.150 % February 2017 February 2017  Senior notes 180 6.875 September 2017 March 2018  Total Consumers $ 430  Total CMS Energy $ 430  1 These first mortgage bonds were issued in a September private placement under a bond purchase agreement executed in August. Under the agreement, Consumers will issue an additional $300 million of first mortgage bonds in a second private placement in November, consisting of $60 million of 3.18 -percent first mortgage bonds due 2032 , $210 million of 3.52 -percent first mortgage bonds due 2037 , and $30 million of 3.86 -percent first mortgage bonds due 2052 . In October 2017, Consumers retired $100 million of 3.21 ‑percent first mortgage bonds at maturity. Term Loan: In April 2017, CMS Energy reached an agreement to extend the maturity date of its $180 million term loan by one year, through April 2019. Revolving Credit Facilities: The following secured revolving credit facilities with banks were available at September 30, 2 017 :    In Millions  Expiration Date Amount of Facility Amount Borrowed Letters of Credit Outstanding Amount Available  CMS Energy, parent only  May 27, 2022 1,2 $ 550 $ - $ 1 $ 549  Consumers  May 27, 2022 2,3 $ 650 $ - $ 7 $ 643  November 23, 2018 3 250 - - 250  September 9, 2019 3,4 30 - 30 -  1 During the nine months ended September 30, 2017 , CMS Energy’s average borrowings totaled $28 million with a weighted-average interest rate of 2.02 percent. Obligations under this facility are secured by Consumers common stock. 2 In May 2017, the expiration date of this revolving credit agreement was extended from May 2021 to May 2022. 3 Obligations under this facility are secured by first mortgage bonds of Consumers. 4 In June 2017, the expiration date of this letter of credit reimbursement agreement was extended from May 2018 to September 2019. Short-term Borrowings: Under Consumers’ commercial paper program, Consumers may issue, in one or more placements, commercial paper notes with maturities of up to 365 days and that bear interest at fixed or floating rates. These issuances are supported by Consumers’ revolving credit facilities and may have an aggregate principal amount outstanding of up to $500 million. While the amount of outstanding commercial paper does not reduce the available capacity of the revolving credit facilities , Consumers does not intend to issue commercial paper in an amount exceeding the available capacity. At September 30, 2017, $230 million of commercial paper notes were outstanding under this program and recorded as current notes payable on the consolidated balance sheets of CMS Energy and Consumers . Dividend Restrictions: At September 30, 2017, payment of dividends by CMS Energy on its common stock was limited to $4.5 billion under provisions of the Michigan Business Corporation Act of 1972. Under the provisions of its ar ticles of incorporation, at September 30, 2017, Consumers had $1.1 billion of unrestricted retained earnings available to pay dividends on its common stock to CMS Energy. Provisions of the Federal Power Act and the Natural Gas Act appear to restrict dividends payable by Consumers to the amount of Consumers’ retained earnings. Several decisions from FERC suggest that under a variety of circumstances, dividends from Consumers on its common stock would not be limited to amounts in Consumers’ retained earnings. Any decision by Consumers to pay dividends on its common stock in excess of retained earnings would be based on specific facts and circumstances and would be subject to a formal regulatory filing process. For the nine months ended September 30, 2 017 , Consumers paid $ 347 million in dividends on its common stock to CMS Energy. Issuance of Common Stock: In March 2017, CMS Energy entered into an updated continuous equity offering program permitting it to sell, from time to time in “at the market” offerings, common stock having an aggregate sales price of up to $100 million. Presented in the following table are the transactions that CMS Energy entered into under the program:    Number of Shares Issued Average Price per Share Net Proceeds (In Millions)  June 2017 1,494,371 $ 47.31 $ 70 
Consumers Energy Company [Member]
Financings And Capitalization	4: Financings and Capitalization Financings: Presented in the following table is a summary of major long-term debt transactions during the nine months ended September 30, 2 017 .    Principal (In Millions) Interest Rate Issue/Retirement Date Maturity Date  Debt issuances  CMS Energy, parent only  Senior notes $ 350 3.450 % February 2017 August 2027  Total CMS Energy, parent only $ 350  Consumers  First mortgage bonds $ 350 3.950 % February 2017 July 2047  First mortgage bonds 1 40 3.180 September 2017 September 2032  First mortgage bonds 1 125 3.520 September 2017 September 2037  First mortgage bonds 1 20 3.860 September 2017 September 2052  Total Consumers $ 535  Total CMS Energy $ 885  Debt retirements  Consumers  First mortgage bonds $ 250 5.150 % February 2017 February 2017  Senior notes 180 6.875 September 2017 March 2018  Total Consumers $ 430  Total CMS Energy $ 430  1 These first mortgage bonds were issued in a September private placement under a bond purchase agreement executed in August. Under the agreement, Consumers will issue an additional $300 million of first mortgage bonds in a second private placement in November, consisting of $60 million of 3.18 -percent first mortgage bonds due 2032 , $210 million of 3.52 -percent first mortgage bonds due 2037 , and $30 million of 3.86 -percent first mortgage bonds due 2052 . In October 2017, Consumers retired $100 million of 3.21 ‑percent first mortgage bonds at maturity. Term Loan: In April 2017, CMS Energy reached an agreement to extend the maturity date of its $180 million term loan by one year, through April 2019. Revolving Credit Facilities: The following secured revolving credit facilities with banks were available at September 30, 2 017 :    In Millions  Expiration Date Amount of Facility Amount Borrowed Letters of Credit Outstanding Amount Available  CMS Energy, parent only  May 27, 2022 1,2 $ 550 $ - $ 1 $ 549  Consumers  May 27, 2022 2,3 $ 650 $ - $ 7 $ 643  November 23, 2018 3 250 - - 250  September 9, 2019 3,4 30 - 30 -  1 During the nine months ended September 30, 2017 , CMS Energy’s average borrowings totaled $28 million with a weighted-average interest rate of 2.02 percent. Obligations under this facility are secured by Consumers common stock. 2 In May 2017, the expiration date of this revolving credit agreement was extended from May 2021 to May 2022. 3 Obligations under this facility are secured by first mortgage bonds of Consumers. 4 In June 2017, the expiration date of this letter of credit reimbursement agreement was extended from May 2018 to September 2019. Short-term Borrowings: Under Consumers’ commercial paper program, Consumers may issue, in one or more placements, commercial paper notes with maturities of up to 365 days and that bear interest at fixed or floating rates. These issuances are supported by Consumers’ revolving credit facilities and may have an aggregate principal amount outstanding of up to $500 million. While the amount of outstanding commercial paper does not reduce the available capacity of the revolving credit facilities , Consumers does not intend to issue commercial paper in an amount exceeding the available capacity. At September 30, 2017, $230 million of commercial paper notes were outstanding under this program and recorded as current notes payable on the consolidated balance sheets of CMS Energy and Consumers . Dividend Restrictions: At September 30, 2017, payment of dividends by CMS Energy on its common stock was limited to $4.5 billion under provisions of the Michigan Business Corporation Act of 1972. Under the provisions of its ar ticles of incorporation, at September 30, 2017, Consumers had $1.1 billion of unrestricted retained earnings available to pay dividends on its common stock to CMS Energy. Provisions of the Federal Power Act and the Natural Gas Act appear to restrict dividends payable by Consumers to the amount of Consumers’ retained earnings. Several decisions from FERC suggest that under a variety of circumstances, dividends from Consumers on its common stock would not be limited to amounts in Consumers’ retained earnings. Any decision by Consumers to pay dividends on its common stock in excess of retained earnings would be based on specific facts and circumstances and would be subject to a formal regulatory filing process. For the nine months ended September 30, 2 017 , Consumers paid $ 347 million in dividends on its common stock to CMS Energy. Issuance of Common Stock: In March 2017, CMS Energy entered into an updated continuous equity offering program permitting it to sell, from time to time in “at the market” offerings, common stock having an aggregate sales price of up to $100 million. Presented in the following table are the transactions that CMS Energy entered into under the program:    Number of Shares Issued Average Price per Share Net Proceeds (In Millions)  June 2017 1,494,371 $ 47.31 $ 70 

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Measurements	5 : Fair Value Measurements Accounting standards define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. When measuring fair value, CMS Energy and Consumers are required to incorporate all assumptions that market participants would use in pricing an asset or liability, including assumptions about risk. A fair value hierarchy prioritizes inputs used to measure fair value according to their observability in the market. The three levels of the fair value hierarchy are as follows: · Level 1 inputs are unadjusted quoted prices in active markets for identical assets or liabilities. · Level 2 inputs are observable, market-based inputs, other than Level 1 prices. Level 2 inputs may include quoted prices for similar assets or liabilities in active markets, quoted prices in inactive markets, and inputs derived from or corroborated by observable market data. · Level 3 inputs are unobservable inputs that reflect CMS Energy’s or Consumers’ own assumptions about how market participants would value their assets and liabilities. CMS Energy and Consumers classify fair value measurements within the fair value hierarchy based on the lowest level of input that is significant to the fair value measurement in its entirety. Assets and Liabilities Measured at Fair Value on a Recurring Basis Presented in the following table are CMS Energy’s and Consumers’ assets and liabilities recorded at fair value on a recurring basis:    In Millions  CMS Energy, including Consumers Consumers  September 30 December 31 September 30 December 31  2017 2016 2017 2016  Assets 1  Cash equivalents $ 21 $ 44 $ - $ -  Restricted cash equivalents 27 19 27 19  CMS Energy common stock - - 21 33  Nonqualified deferred compensation plan assets 13 12 9 8  DB SERP  Cash equivalents 4 3 3 2  Mutual funds 145 141 105 102  Derivative instruments  Commodity contracts 2 1 2 1  Total $ 212 $ 220 $ 167 $ 165  Liabilities 1  Nonqualified deferred compensation plan liabilities $ 13 $ 12 $ 9 $ 8  Derivative instruments  Commodity contracts 1 - 1 -  Total $ 14 $ 12 $ 10 $ 8  1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3. Cash Equivalents: Cash equivalents and restricted cash equivalents consist of money market funds with daily liquidity. Short-term debt instruments classified as cash equivalents on the consolidated balance sheets are not included since they are recorded at amortized cost. Nonqualified Deferred Compensation Plan Assets and Liabilities: The nonqualified deferred compensation plan assets consist of mutual funds, which are valued using the daily quoted net asset value s. CMS Energy and Consumers value their nonqualified deferred compensation plan liabilities based on the fair values of the plan assets, as they reflect what is owed to the plan participants in accordance with their investment elections. CMS Energy and Consumers report the assets in other non ‑current assets and the liabilities in other non ‑current liabilities on their consolidated balance sheets. DB SERP Assets: The DB SERP cash equivalents consist of a money market fund with daily liquidity. The DB SERP invests in mutual funds that hold primarily fixed-income instruments of varying maturities. In order to meet their investment objectives, the funds hold investment-grade debt securities , and may invest a portion of their assets in high-yield securities, foreign debt, and derivative instruments. CMS Energy and Consumers value these funds using the daily quoted net asset value s. CMS Energy and Consumers report their DB SERP assets in other non ‑current assets on their consolidated balance sheets. For additional details about DB SERP securities, see Note 6, Financial Instruments. Derivative Instruments: CMS Energy and Consumers value their derivative instruments using either a market approach that incorporates information from market transactions, or an income approach that discounts future expected cash flows to a present value amount. CMS Energy values its exchange-traded derivative contracts based on Level 1 quoted prices. CMS Energy’s and Consumers’ remaining derivatives are classified as Level 3. The majority of these derivatives are FTRs held by Consumers. Consumers uses FTRs to manage price risk related to electricity transmission congestion. An FTR is a financial instrument that entitles its holder to receive compensation or requires its holder to remit payment for congestion-related transmission charges. Under regulatory accounting, all changes in fair value associated with FTRs are deferred as regulatory assets and liabilities until the instruments are settled. Due to the lack of quoted pricing information, Consumers determines the fair value of its FTRs based on Consumers’ average historical settlements.
Consumers Energy Company [Member]
Fair Value Measurements	5 : Fair Value Measurements Accounting standards define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. When measuring fair value, CMS Energy and Consumers are required to incorporate all assumptions that market participants would use in pricing an asset or liability, including assumptions about risk. A fair value hierarchy prioritizes inputs used to measure fair value according to their observability in the market. The three levels of the fair value hierarchy are as follows: · Level 1 inputs are unadjusted quoted prices in active markets for identical assets or liabilities. · Level 2 inputs are observable, market-based inputs, other than Level 1 prices. Level 2 inputs may include quoted prices for similar assets or liabilities in active markets, quoted prices in inactive markets, and inputs derived from or corroborated by observable market data. · Level 3 inputs are unobservable inputs that reflect CMS Energy’s or Consumers’ own assumptions about how market participants would value their assets and liabilities. CMS Energy and Consumers classify fair value measurements within the fair value hierarchy based on the lowest level of input that is significant to the fair value measurement in its entirety. Assets and Liabilities Measured at Fair Value on a Recurring Basis Presented in the following table are CMS Energy’s and Consumers’ assets and liabilities recorded at fair value on a recurring basis:    In Millions  CMS Energy, including Consumers Consumers  September 30 December 31 September 30 December 31  2017 2016 2017 2016  Assets 1  Cash equivalents $ 21 $ 44 $ - $ -  Restricted cash equivalents 27 19 27 19  CMS Energy common stock - - 21 33  Nonqualified deferred compensation plan assets 13 12 9 8  DB SERP  Cash equivalents 4 3 3 2  Mutual funds 145 141 105 102  Derivative instruments  Commodity contracts 2 1 2 1  Total $ 212 $ 220 $ 167 $ 165  Liabilities 1  Nonqualified deferred compensation plan liabilities $ 13 $ 12 $ 9 $ 8  Derivative instruments  Commodity contracts 1 - 1 -  Total $ 14 $ 12 $ 10 $ 8  1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3. Cash Equivalents: Cash equivalents and restricted cash equivalents consist of money market funds with daily liquidity. Short-term debt instruments classified as cash equivalents on the consolidated balance sheets are not included since they are recorded at amortized cost. Nonqualified Deferred Compensation Plan Assets and Liabilities: The nonqualified deferred compensation plan assets consist of mutual funds, which are valued using the daily quoted net asset value s. CMS Energy and Consumers value their nonqualified deferred compensation plan liabilities based on the fair values of the plan assets, as they reflect what is owed to the plan participants in accordance with their investment elections. CMS Energy and Consumers report the assets in other non ‑current assets and the liabilities in other non ‑current liabilities on their consolidated balance sheets. DB SERP Assets: The DB SERP cash equivalents consist of a money market fund with daily liquidity. The DB SERP invests in mutual funds that hold primarily fixed-income instruments of varying maturities. In order to meet their investment objectives, the funds hold investment-grade debt securities , and may invest a portion of their assets in high-yield securities, foreign debt, and derivative instruments. CMS Energy and Consumers value these funds using the daily quoted net asset value s. CMS Energy and Consumers report their DB SERP assets in other non ‑current assets on their consolidated balance sheets. For additional details about DB SERP securities, see Note 6, Financial Instruments. Derivative Instruments: CMS Energy and Consumers value their derivative instruments using either a market approach that incorporates information from market transactions, or an income approach that discounts future expected cash flows to a present value amount. CMS Energy values its exchange-traded derivative contracts based on Level 1 quoted prices. CMS Energy’s and Consumers’ remaining derivatives are classified as Level 3. The majority of these derivatives are FTRs held by Consumers. Consumers uses FTRs to manage price risk related to electricity transmission congestion. An FTR is a financial instrument that entitles its holder to receive compensation or requires its holder to remit payment for congestion-related transmission charges. Under regulatory accounting, all changes in fair value associated with FTRs are deferred as regulatory assets and liabilities until the instruments are settled. Due to the lack of quoted pricing information, Consumers determines the fair value of its FTRs based on Consumers’ average historical settlements.

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2017
Financial Instruments	6: Financial Instruments Presented in the following table are the carrying amounts and fair values, by level within the fair value hierarchy, of CMS Energy’s and Consumers’ financial instruments that are not recorded at fair value. The table excludes cash, cash equivalents, short-term financial instruments, and trade accounts receivable and payable whose carrying amounts approximate their fair values. For information about assets and liabilities recorded at fair value and for additional details regarding the fair value hierarchy, see Note 5, Fair Value Measurements.    In Millions  September 30, 2017 December 31, 2016  Fair Value Fair Value  Carrying Level Carrying Level  Amount Total 1 2 3 Amount Total 1 2 3  CMS Energy, including Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ 22 $ 22 $ - $ - $ 22  Notes receivable 2 1,382 1,479 - - 1,479 1,326 1,415 - - 1,415  Securities held to maturity 16 16 - 16 - 13 13 - 13 -  Liabilities  Long-term debt 3 9,983 10,484 - 9,331 1,153 9,504 9,953 - 8,990 963  Long-term payables 4 18 18 - - 18 17 17 - - 17  Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ 22 $ 22 $ - $ - $ 22  Notes receivable 5 46 46 - - 46 45 45 - - 45  Liabilities  Long-term debt 6 5,718 6,032 - 4,879 1,153 5,628 5,903 - 4,940 963  1 Includes current accounts receivable of $14 million at September 30, 2 017 and $12 million at December 31, 20 16 . 2 Includes current portion of notes receivable of $228 million at September 30, 2 017 and $ 219 million at December 31, 20 16 . 3 Includes current portion of long-term debt of $959 million at September 30, 2 017 and $ 864 million at December 31, 20 16 . 4 Includes current portion of long-term payables of $1 million at September 30, 2 017 and December 31, 20 16 . 5 Includes current portion of notes receivable of $30 million at September 30, 2 017 and $29 million at December 31, 20 16 . 6 Includes current portion of long-term debt of $443 million at September 30, 2 017 and $ 375 million at December 31, 20 16 . At CMS Energy, notes receivable consist primarily of EnerBank’s fixed-rate installment loans. EnerBank estimates the fair value of these loans using a discounted cash flows technique that incorporates market interest rates as well as assumptions about the remaining life of the loans and credit risk. CMS Energy and Consumers estimate the fair value of their long-term debt using quoted prices from market trades of the debt, if available. In the absence of quoted prices, CMS Energy and Consumers calculate market yields and prices for the debt using a matrix method that incorporates market data for similarly rated debt. Depending on the information available, other valuation techniques and models may be used that rely on assumptions that cannot be observed or confirmed through market transactions. The effects of third-party credit enhancements are excluded from the fair value measurements of long-term debt. At September 30, 2 017 and December 31, 20 16 , CMS Energy’s long-term debt included $ 103 million principal amount that was supported by third-party credit enhancements. This entire principal amount was at Consumers. Presented in the following table are CMS Energy’s and Consumers’ investment securities classified as available for sale or held to maturity:    In Millions  September 30, 2017 December 31, 2016  Unrealized Unrealized Fair Unrealized Unrealized Fair  Cost Gains Losses Value Cost Gains Losses Value  CMS Energy, including Consumers  Available for sale  DB SERP  Mutual funds $ 142 $ 3 $ - $ 145 $ 141 $ - $ - $ 141  Held to maturity  Debt securities 16 - - 16 13 - - 13  Consumers  Available for sale  DB SERP  Mutual funds $ 103 $ 2 $ - $ 105 $ 102 $ - $ - $ 102  CMS Energy common stock 2 19 - 21 4 29 - 33  The mutual funds classified as available for sale hold primarily fixed-income instruments of varying maturities. Debt securities classified as held to maturity consist primarily of mortgage-backed securities and Utah Housing Corporation bonds held by EnerBank.
Consumers Energy Company [Member]
Financial Instruments	6: Financial Instruments Presented in the following table are the carrying amounts and fair values, by level within the fair value hierarchy, of CMS Energy’s and Consumers’ financial instruments that are not recorded at fair value. The table excludes cash, cash equivalents, short-term financial instruments, and trade accounts receivable and payable whose carrying amounts approximate their fair values. For information about assets and liabilities recorded at fair value and for additional details regarding the fair value hierarchy, see Note 5, Fair Value Measurements.    In Millions  September 30, 2017 December 31, 2016  Fair Value Fair Value  Carrying Level Carrying Level  Amount Total 1 2 3 Amount Total 1 2 3  CMS Energy, including Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ 22 $ 22 $ - $ - $ 22  Notes receivable 2 1,382 1,479 - - 1,479 1,326 1,415 - - 1,415  Securities held to maturity 16 16 - 16 - 13 13 - 13 -  Liabilities  Long-term debt 3 9,983 10,484 - 9,331 1,153 9,504 9,953 - 8,990 963  Long-term payables 4 18 18 - - 18 17 17 - - 17  Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ 22 $ 22 $ - $ - $ 22  Notes receivable 5 46 46 - - 46 45 45 - - 45  Liabilities  Long-term debt 6 5,718 6,032 - 4,879 1,153 5,628 5,903 - 4,940 963  1 Includes current accounts receivable of $14 million at September 30, 2 017 and $12 million at December 31, 20 16 . 2 Includes current portion of notes receivable of $228 million at September 30, 2 017 and $ 219 million at December 31, 20 16 . 3 Includes current portion of long-term debt of $959 million at September 30, 2 017 and $ 864 million at December 31, 20 16 . 4 Includes current portion of long-term payables of $1 million at September 30, 2 017 and December 31, 20 16 . 5 Includes current portion of notes receivable of $30 million at September 30, 2 017 and $29 million at December 31, 20 16 . 6 Includes current portion of long-term debt of $443 million at September 30, 2 017 and $ 375 million at December 31, 20 16 . At CMS Energy, notes receivable consist primarily of EnerBank’s fixed-rate installment loans. EnerBank estimates the fair value of these loans using a discounted cash flows technique that incorporates market interest rates as well as assumptions about the remaining life of the loans and credit risk. CMS Energy and Consumers estimate the fair value of their long-term debt using quoted prices from market trades of the debt, if available. In the absence of quoted prices, CMS Energy and Consumers calculate market yields and prices for the debt using a matrix method that incorporates market data for similarly rated debt. Depending on the information available, other valuation techniques and models may be used that rely on assumptions that cannot be observed or confirmed through market transactions. The effects of third-party credit enhancements are excluded from the fair value measurements of long-term debt. At September 30, 2 017 and December 31, 20 16 , CMS Energy’s long-term debt included $ 103 million principal amount that was supported by third-party credit enhancements. This entire principal amount was at Consumers. Presented in the following table are CMS Energy’s and Consumers’ investment securities classified as available for sale or held to maturity:    In Millions  September 30, 2017 December 31, 2016  Unrealized Unrealized Fair Unrealized Unrealized Fair  Cost Gains Losses Value Cost Gains Losses Value  CMS Energy, including Consumers  Available for sale  DB SERP  Mutual funds $ 142 $ 3 $ - $ 145 $ 141 $ - $ - $ 141  Held to maturity  Debt securities 16 - - 16 13 - - 13  Consumers  Available for sale  DB SERP  Mutual funds $ 103 $ 2 $ - $ 105 $ 102 $ - $ - $ 102  CMS Energy common stock 2 19 - 21 4 29 - 33  The mutual funds classified as available for sale hold primarily fixed-income instruments of varying maturities. Debt securities classified as held to maturity consist primarily of mortgage-backed securities and Utah Housing Corporation bonds held by EnerBank.

Notes Receivable

Notes Receivable	9 Months Ended
	Sep. 30, 2017
Notes Receivable	7: Notes Receivable Presented in the following table are details of CMS Energy’s and Consumers’ current and non ‑current notes receivable:    In Millions  September 30, 2017 December 31, 2016  CMS Energy, including Consumers  Current  EnerBank notes receivable, net of allowance for loan losses $ 167 $ 151  EnerBank notes receivable held for sale 31 39  Michigan tax settlement 30 29  Non-current  EnerBank notes receivable 1,134 1,088  Michigan tax settlement 20 19  Total notes receivable $ 1,382 $ 1,326  Consumers  Current  Michigan tax settlement $ 30 $ 29  Non-current  Michigan tax settlement 16 16  Total notes receivable $ 46 $ 45  EnerBank notes receivable are unsecured consumer installment loans for financing home improvements. EnerBank records its notes receivable at cost, less an allowance for loan losses. In March 2017, EnerBank completed a sale of notes receivable, receiving proceeds of $19 million and recording an insignificant gai n. At September 30, 2017, $31 million of notes receivable remained classified as held for sale; the fair value of notes receivable held for sale exceeded their carrying value. These notes are expected to be sold in 2017. Authorized contractors pay fees to EnerBank to provide borrowers with same-as-cash, zero interest, or reduced interest loans. Unearned income associated with the loan fees, which is recorded as a reduction to notes receivable on CMS Energy’s consolidated balance sheets, was $83 million at September 30, 2017 and $84 million at December 31, 2016. Unearned income associated with the loan fees for notes receivable held for sale was $6 million at September 30, 2017 and $8 million at December 31, 2016. The allowance for loan losses is a valuation allowance to reflect estimated credit losses. The allowance is increased by the provision for loan losses and decreased by loan charge-offs net of recoveries. Management estimates the allowance balance required by taking into consideration historical loan loss experience, the nature and volume of the portfolio, economic conditions, and other factors. Loan losses are charged against the allowance when the loss is confirmed, but no later than the point at which a loan becomes 120 days past due. Loans that are 30 days or more past due are considered delinquent. The balance of EnerBank’s delinquent consumer loans was $12 million at September 30, 2017 and $11 million at December 31, 2016. At September 30, 2017 and December 31, 2016, $ 1 million of EnerBank’s loans had been modified as troubled debt restructurings.
Consumers Energy Company [Member]
Notes Receivable	7: Notes Receivable Presented in the following table are details of CMS Energy’s and Consumers’ current and non ‑current notes receivable:    In Millions  September 30, 2017 December 31, 2016  CMS Energy, including Consumers  Current  EnerBank notes receivable, net of allowance for loan losses $ 167 $ 151  EnerBank notes receivable held for sale 31 39  Michigan tax settlement 30 29  Non-current  EnerBank notes receivable 1,134 1,088  Michigan tax settlement 20 19  Total notes receivable $ 1,382 $ 1,326  Consumers  Current  Michigan tax settlement $ 30 $ 29  Non-current  Michigan tax settlement 16 16  Total notes receivable $ 46 $ 45  EnerBank notes receivable are unsecured consumer installment loans for financing home improvements. EnerBank records its notes receivable at cost, less an allowance for loan losses. In March 2017, EnerBank completed a sale of notes receivable, receiving proceeds of $19 million and recording an insignificant gai n. At September 30, 2017, $31 million of notes receivable remained classified as held for sale; the fair value of notes receivable held for sale exceeded their carrying value. These notes are expected to be sold in 2017. Authorized contractors pay fees to EnerBank to provide borrowers with same-as-cash, zero interest, or reduced interest loans. Unearned income associated with the loan fees, which is recorded as a reduction to notes receivable on CMS Energy’s consolidated balance sheets, was $83 million at September 30, 2017 and $84 million at December 31, 2016. Unearned income associated with the loan fees for notes receivable held for sale was $6 million at September 30, 2017 and $8 million at December 31, 2016. The allowance for loan losses is a valuation allowance to reflect estimated credit losses. The allowance is increased by the provision for loan losses and decreased by loan charge-offs net of recoveries. Management estimates the allowance balance required by taking into consideration historical loan loss experience, the nature and volume of the portfolio, economic conditions, and other factors. Loan losses are charged against the allowance when the loss is confirmed, but no later than the point at which a loan becomes 120 days past due. Loans that are 30 days or more past due are considered delinquent. The balance of EnerBank’s delinquent consumer loans was $12 million at September 30, 2017 and $11 million at December 31, 2016. At September 30, 2017 and December 31, 2016, $ 1 million of EnerBank’s loans had been modified as troubled debt restructurings.

Retirement Benefits

Retirement Benefits	9 Months Ended
	Sep. 30, 2017
Retirement Benefits	8 : Retirement Benefits CMS Energy and Consumers provide pension, OPEB, and other retirement benefits to employees under a number of different plans. CMS Energy and Consumers elected to adopt ASU 2017 ‑ 07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, as of January 1, 2017. For further details on the implementation of this standard, see Note 1, New Accounting Standards. Presented in the following table are the costs (credits) and other changes in plan assets and benefit obligations incurred in CMS Energy’s and Consumers’ retirement benefits plans:    In Millions  DB Pension Plan OPEB Plan  Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016 2017 2016 2017 2016  CMS Energy, including Consumers  Net periodic cost (credit)  Service cost $ 12 $ 10 $ 34 $ 31 $ 5 $ 5 $ 15 $ 14  Interest cost 23 21 67 64 13 12 39 35  Expected return on plan assets (39) (36) (115) (110) (22) (22) (67) (65)  Amortization of:  Net loss 20 17 60 52 7 5 23 16  Prior service cost (credit) 1 1 3 3 (8) (10) (26) (31)  Net periodic cost (credit) $ 17 $ 13 $ 49 $ 40 $ (5) $ (10) $ (16) $ (31)  Consumers  Net periodic cost (credit)  Service cost $ 11 $ 11 $ 33 $ 31 $ 5 $ 4 $ 14 $ 13  Interest cost 22 20 65 62 12 12 38 34  Expected return on plan assets (38) (35) (112) (107) (21) (20) (63) (60)  Amortization of:  Net loss 19 16 58 50 8 5 24 16  Prior service cost (credit) 1 1 3 3 (8) (10) (25) (30)  Net periodic cost (credit) $ 15 $ 13 $ 47 $ 39 $ (4) $ (9) $ (12) $ (27) 
Consumers Energy Company [Member]
Retirement Benefits	8 : Retirement Benefits CMS Energy and Consumers provide pension, OPEB, and other retirement benefits to employees under a number of different plans. CMS Energy and Consumers elected to adopt ASU 2017 ‑ 07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, as of January 1, 2017. For further details on the implementation of this standard, see Note 1, New Accounting Standards. Presented in the following table are the costs (credits) and other changes in plan assets and benefit obligations incurred in CMS Energy’s and Consumers’ retirement benefits plans:    In Millions  DB Pension Plan OPEB Plan  Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016 2017 2016 2017 2016  CMS Energy, including Consumers  Net periodic cost (credit)  Service cost $ 12 $ 10 $ 34 $ 31 $ 5 $ 5 $ 15 $ 14  Interest cost 23 21 67 64 13 12 39 35  Expected return on plan assets (39) (36) (115) (110) (22) (22) (67) (65)  Amortization of:  Net loss 20 17 60 52 7 5 23 16  Prior service cost (credit) 1 1 3 3 (8) (10) (26) (31)  Net periodic cost (credit) $ 17 $ 13 $ 49 $ 40 $ (5) $ (10) $ (16) $ (31)  Consumers  Net periodic cost (credit)  Service cost $ 11 $ 11 $ 33 $ 31 $ 5 $ 4 $ 14 $ 13  Interest cost 22 20 65 62 12 12 38 34  Expected return on plan assets (38) (35) (112) (107) (21) (20) (63) (60)  Amortization of:  Net loss 19 16 58 50 8 5 24 16  Prior service cost (credit) 1 1 3 3 (8) (10) (25) (30)  Net periodic cost (credit) $ 15 $ 13 $ 47 $ 39 $ (4) $ (9) $ (12) $ (27) 

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Taxes	9: Income Taxes Presented in the following table is a reconciliation of the statutory U.S. federal income tax rate to the effective income tax rate from continuing operations:    Nine Months Ended September 30 2017 2016  CMS Energy, including Consumers  U.S. federal income tax rate 35.0 % 35.0 %  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 1 2.3 4.2  Accelerated flow-through of regulatory tax benefits 2 (4.3) (4.7)  Employee share-based awards (0.9) (0.8)  Other, net (2.0) (1.4)  Effective tax rate 30.1 % 32.3 %  Consumers  U.S. federal income tax rate 35.0 % 35.0 %  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 1 2.3 4.6  Accelerated flow-through of regulatory tax benefits 2 (3.9) (4.0)  Employee share-based awards (0.8) (0.7)  Other, net (2.3) (1.2)  Effective tax rate 30.3 % 33.7 %  1 In September 2017, CMS Energy completed the evaluation of its methodology for the state apportionment of Consumers’ electricity sales to MISO, taking into account recent state tax law developments in the electric utility sector. As a result, CMS Energy intends to amend state income tax filings for 2013 through 2016 to seek a refund of taxes previously paid. To recognize the anticipated refund and the impact of the expected lower effective tax rate on their deferred state tax liabilities, CMS Energy recorded a $15 million income tax benefit and Consumers recorded a $16 million income tax benefit in September 2017. Both amounts are net of reserves for uncertain tax positions. For the nine months ended September 30, 2017, the impact of the benefit was a 2.3 percentage point reduction to CMS Energy’s effective tax rate and a 2.2 percentage point reduction to Consumers’ effective tax rate. 2 Since 2014, Consumers has followed a regulatory treatment ordered by the MPSC that accelerates the return of certain income tax benefits to customers. This change, which also accelerates Consumers’ recognition of the income tax benefits, reduced Consumers’ income tax expense by $28 million for the nine months ended September 30, 2017 and by $30 million for the nine months ended September 30, 2016.
Consumers Energy Company [Member]
Income Taxes	9: Income Taxes Presented in the following table is a reconciliation of the statutory U.S. federal income tax rate to the effective income tax rate from continuing operations:    Nine Months Ended September 30 2017 2016  CMS Energy, including Consumers  U.S. federal income tax rate 35.0 % 35.0 %  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 1 2.3 4.2  Accelerated flow-through of regulatory tax benefits 2 (4.3) (4.7)  Employee share-based awards (0.9) (0.8)  Other, net (2.0) (1.4)  Effective tax rate 30.1 % 32.3 %  Consumers  U.S. federal income tax rate 35.0 % 35.0 %  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 1 2.3 4.6  Accelerated flow-through of regulatory tax benefits 2 (3.9) (4.0)  Employee share-based awards (0.8) (0.7)  Other, net (2.3) (1.2)  Effective tax rate 30.3 % 33.7 %  1 In September 2017, CMS Energy completed the evaluation of its methodology for the state apportionment of Consumers’ electricity sales to MISO, taking into account recent state tax law developments in the electric utility sector. As a result, CMS Energy intends to amend state income tax filings for 2013 through 2016 to seek a refund of taxes previously paid. To recognize the anticipated refund and the impact of the expected lower effective tax rate on their deferred state tax liabilities, CMS Energy recorded a $15 million income tax benefit and Consumers recorded a $16 million income tax benefit in September 2017. Both amounts are net of reserves for uncertain tax positions. For the nine months ended September 30, 2017, the impact of the benefit was a 2.3 percentage point reduction to CMS Energy’s effective tax rate and a 2.2 percentage point reduction to Consumers’ effective tax rate. 2 Since 2014, Consumers has followed a regulatory treatment ordered by the MPSC that accelerates the return of certain income tax benefits to customers. This change, which also accelerates Consumers’ recognition of the income tax benefits, reduced Consumers’ income tax expense by $28 million for the nine months ended September 30, 2017 and by $30 million for the nine months ended September 30, 2016.

Earnings Per Share - CMS Energy

Earnings Per Share - CMS Energy	9 Months Ended
	Sep. 30, 2017
Earnings Per Share - CMS Energy [Abstract]
Earnings Per Share - CMS Energy	10: Earnings Per Share—CMS Energy Presented in the following table are CMS Energy’s basic and diluted EPS computations based on net income:    In Millions, Except Per Share Amounts  Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016  Income available to common stockholders  Net income $ 172 $ 186 $ 464 $ 475  Less income attributable to noncontrolling interests - - 1 1  Net income available to common stockholders – basic and diluted $ 172 $ 186 $ 463 $ 474  Average common shares outstanding  Weighted-average shares – basic 280.8 278.2 279.8 277.7  Add dilutive nonvested stock awards 0.8 1.0 0.8 1.1  Weighted-average shares – diluted 281.6 279.2 280.6 278.8  Net income per average common share available to common stockholders  Basic $ 0.61 $ 0.67 $ 1.65 $ 1.71  Diluted 0.61 0.67 1.65 1.70  Nonvested Stock Awards CMS Energy’s nonvested stock awards are composed of participating and non ‑participating securities. The participating securities accrue cash dividends when common stockholders receive dividends. Since the recipient is not required to return the dividends to CMS Energy if the recipient forfeits the award, the nonvested stock awards are considered participating securities. As such, the participating nonvested stock awards were included in the computation of basic EPS. The non ‑participating securities accrue stock dividends that vest concurrently with the stock award. If the recipient forfeits the award, the stock dividends accrued on the non ‑participating securities are also forfeited. Accordingly, the non ‑participating awards and stock dividends were included in the computation of diluted EPS, but not basic EPS.

Cash And Cash Equivalents

Cash And Cash Equivalents	9 Months Ended
	Sep. 30, 2017
Cash And Cash Equivalents	11: Cash and Cash Equivalents Presented in the following table are the components of total cash and cash equivalents, including restricted amounts, and their location on CMS Energy’s and Consumers’ consolidated balance sheets:    In Millions  September 30 December 31  2017 2016  CMS Energy, including Consumers  Cash and cash equivalents $ 142 $ 235  Restricted cash and cash equivalents 27 19  Other non-current assets 4 3  Cash and cash equivalents, including restricted amounts $ 173 $ 257  Consumers  Cash and cash equivalents $ 55 $ 131  Restricted cash and cash equivalents 27 19  Other non-current assets 3 2  Cash and cash equivalents, including restricted amounts $ 85 $ 152  Cash and Cash Equivalents: Cash and cash equivalents include short-term, highly liquid investments with original maturities of three months or less. Restricted Cash and Cash Equivalents: Restricted cash and cash equivalents are held primarily for the repayment of securitization bonds. Cash and cash equivalents may also be restricted to pay other contractual obligations such as leasing of coal rail cars. These amounts are classified as current assets since they relate to payments that could or will occur within one year. Other Non ‑c urrent Assets: The cash equivalents classified as other non ‑ current assets represent an investment in a money market fund held in the DB SERP rabbi trust. See Note 5 , Fair Value Measurements for more information regarding the DB SERP. Implementation of ASU 2016 ‑ 18, Restricted Cash : CMS Energy and Consumers have early adopted the provisions of ASU 2016 ‑ 18 , Restricted Cash , which requires restricted cash and cash equivalents to be included with cash and cash equivalents when reconciling beginning-of-period and end-of-period amounts shown on the statement of cash flows. In addition, the standard requires that entities apply the new guidance retrospectively to all prior periods presented. Accordingly, CMS Energy and Consumers made the following adjustments to prior-period amounts on their consolidated statements of cash flows:    In Millions  Nine Months Ended September 30 2016  CMS Energy, including Consumers  Change in:  Net cash used in investing activities $ 7  Cash and cash equivalents, including restricted amounts, end of period 29  Consumers  Change in:  Net cash used in investing activities $ 8  Cash and cash equivalents, including restricted amounts, end of period 29 
Consumers Energy Company [Member]
Cash And Cash Equivalents	11: Cash and Cash Equivalents Presented in the following table are the components of total cash and cash equivalents, including restricted amounts, and their location on CMS Energy’s and Consumers’ consolidated balance sheets:    In Millions  September 30 December 31  2017 2016  CMS Energy, including Consumers  Cash and cash equivalents $ 142 $ 235  Restricted cash and cash equivalents 27 19  Other non-current assets 4 3  Cash and cash equivalents, including restricted amounts $ 173 $ 257  Consumers  Cash and cash equivalents $ 55 $ 131  Restricted cash and cash equivalents 27 19  Other non-current assets 3 2  Cash and cash equivalents, including restricted amounts $ 85 $ 152  Cash and Cash Equivalents: Cash and cash equivalents include short-term, highly liquid investments with original maturities of three months or less. Restricted Cash and Cash Equivalents: Restricted cash and cash equivalents are held primarily for the repayment of securitization bonds. Cash and cash equivalents may also be restricted to pay other contractual obligations such as leasing of coal rail cars. These amounts are classified as current assets since they relate to payments that could or will occur within one year. Other Non ‑c urrent Assets: The cash equivalents classified as other non ‑ current assets represent an investment in a money market fund held in the DB SERP rabbi trust. See Note 5 , Fair Value Measurements for more information regarding the DB SERP. Implementation of ASU 2016 ‑ 18, Restricted Cash : CMS Energy and Consumers have early adopted the provisions of ASU 2016 ‑ 18 , Restricted Cash , which requires restricted cash and cash equivalents to be included with cash and cash equivalents when reconciling beginning-of-period and end-of-period amounts shown on the statement of cash flows. In addition, the standard requires that entities apply the new guidance retrospectively to all prior periods presented. Accordingly, CMS Energy and Consumers made the following adjustments to prior-period amounts on their consolidated statements of cash flows:    In Millions  Nine Months Ended September 30 2016  CMS Energy, including Consumers  Change in:  Net cash used in investing activities $ 7  Cash and cash equivalents, including restricted amounts, end of period 29  Consumers  Change in:  Net cash used in investing activities $ 8  Cash and cash equivalents, including restricted amounts, end of period 29 

Reportable Segments

Reportable Segments	9 Months Ended
	Sep. 30, 2017
Reportable Segments	12: Reportable Segments Reportable segments consist of business units defined by the products and services they offer. CMS Energy and Consumers evaluate the performance of each segment based on its contribution to net income available to CMS Energy’s common stockholders. CMS Energy The reportable segments for CMS Energy are: · electric utility, consisting of regulated activities associated with the generation, transmission, and distribution of electricity in Michigan · gas utility, consisting of regulated activities associated with the transportation, storage, and distribution of natural gas in Michigan · enterprises, consisting of various subsidiaries engaging primarily in domestic independent power production CMS Energy presents EnerBank and corporate interest and other expenses within other reconciling items. Consumers The reportable segments for Consumers are: · electric utility, consisting of regulated activities associated with the generation, transmission, and distribution of electricity in Michigan · gas utility, consisting of regulated activities associated with the transportation, storage, and distribution of natural gas in Michigan Consumers’ other consolidated entities are presented within other reconciling items. Presented in the following tables is financial information by reportable segment:    In Millions  Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016  CMS Energy, including Consumers  Operating revenue  Electric utility $ 1,247 $ 1,313 $ 3,360 $ 3,348  Gas utility 190 185 1,176 1,166  Enterprises 58 59 172 156  Other reconciling items 32 30 97 89  Total operating revenue – CMS Energy $ 1,527 $ 1,587 $ 4,805 $ 4,759  Consumers  Operating revenue  Electric utility $ 1,247 $ 1,313 $ 3,360 $ 3,348  Gas utility 190 185 1,176 1,166  Total operating revenue – Consumers $ 1,437 $ 1,498 $ 4,536 $ 4,514  CMS Energy, including Consumers  Net income (loss) available to common stockholders  Electric utility $ 176 $ 191 $ 394 $ 395  Gas utility 5 3 101 102  Enterprises 8 8 27 17  Other reconciling items (17) (16) (59) (40)  Total net income available to common stockholders – CMS Energy $ 172 $ 186 $ 463 $ 474  Consumers  Net income available to common stockholder  Electric utility $ 176 $ 191 $ 394 $ 395  Gas utility 5 3 101 102  Other reconciling items - 1 - 1  Total net income available to common stockholder – Consumers $ 181 $ 195 $ 495 $ 498     In Millions  September 30, 2017 December 31, 2016  CMS Energy, including Consumers  Plant, property, and equipment, gross  Electric utility 1 $ 15,056 $ 14,540  Gas utility 1 6,713 6,283  Enterprises 164 157  Other reconciling items 33 30  Total plant, property, and equipment, gross – CMS Energy $ 21,966 $ 21,010  Consumers  Plant, property, and equipment, gross  Electric utility 1 $ 15,056 $ 14,540  Gas utility 1 6,713 6,283  Other reconciling items 15 15  Total plant, property, and equipment, gross – Consumers $ 21,784 $ 20,838  CMS Energy, including Consumers  Total assets  Electric utility 1 $ 13,639 $ 13,429  Gas utility 1 6,701 6,446  Enterprises 280 269  Other reconciling items 1,500 1,478  Total assets – CMS Energy $ 22,120 $ 21,622  Consumers  Total assets  Electric utility 1 $ 13,640 $ 13,430  Gas utility 1 6,701 6,446  Other reconciling items 39 70  Total assets – Consumers $ 20,380 $ 19,946  1 Amounts include a portion of Consumers’ other common assets attributable to both the electric and gas utility businesses.
Consumers Energy Company [Member]
Reportable Segments	12: Reportable Segments Reportable segments consist of business units defined by the products and services they offer. CMS Energy and Consumers evaluate the performance of each segment based on its contribution to net income available to CMS Energy’s common stockholders. CMS Energy The reportable segments for CMS Energy are: · electric utility, consisting of regulated activities associated with the generation, transmission, and distribution of electricity in Michigan · gas utility, consisting of regulated activities associated with the transportation, storage, and distribution of natural gas in Michigan · enterprises, consisting of various subsidiaries engaging primarily in domestic independent power production CMS Energy presents EnerBank and corporate interest and other expenses within other reconciling items. Consumers The reportable segments for Consumers are: · electric utility, consisting of regulated activities associated with the generation, transmission, and distribution of electricity in Michigan · gas utility, consisting of regulated activities associated with the transportation, storage, and distribution of natural gas in Michigan Consumers’ other consolidated entities are presented within other reconciling items. Presented in the following tables is financial information by reportable segment:    In Millions  Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016  CMS Energy, including Consumers  Operating revenue  Electric utility $ 1,247 $ 1,313 $ 3,360 $ 3,348  Gas utility 190 185 1,176 1,166  Enterprises 58 59 172 156  Other reconciling items 32 30 97 89  Total operating revenue – CMS Energy $ 1,527 $ 1,587 $ 4,805 $ 4,759  Consumers  Operating revenue  Electric utility $ 1,247 $ 1,313 $ 3,360 $ 3,348  Gas utility 190 185 1,176 1,166  Total operating revenue – Consumers $ 1,437 $ 1,498 $ 4,536 $ 4,514  CMS Energy, including Consumers  Net income (loss) available to common stockholders  Electric utility $ 176 $ 191 $ 394 $ 395  Gas utility 5 3 101 102  Enterprises 8 8 27 17  Other reconciling items (17) (16) (59) (40)  Total net income available to common stockholders – CMS Energy $ 172 $ 186 $ 463 $ 474  Consumers  Net income available to common stockholder  Electric utility $ 176 $ 191 $ 394 $ 395  Gas utility 5 3 101 102  Other reconciling items - 1 - 1  Total net income available to common stockholder – Consumers $ 181 $ 195 $ 495 $ 498     In Millions  September 30, 2017 December 31, 2016  CMS Energy, including Consumers  Plant, property, and equipment, gross  Electric utility 1 $ 15,056 $ 14,540  Gas utility 1 6,713 6,283  Enterprises 164 157  Other reconciling items 33 30  Total plant, property, and equipment, gross – CMS Energy $ 21,966 $ 21,010  Consumers  Plant, property, and equipment, gross  Electric utility 1 $ 15,056 $ 14,540  Gas utility 1 6,713 6,283  Other reconciling items 15 15  Total plant, property, and equipment, gross – Consumers $ 21,784 $ 20,838  CMS Energy, including Consumers  Total assets  Electric utility 1 $ 13,639 $ 13,429  Gas utility 1 6,701 6,446  Enterprises 280 269  Other reconciling items 1,500 1,478  Total assets – CMS Energy $ 22,120 $ 21,622  Consumers  Total assets  Electric utility 1 $ 13,640 $ 13,430  Gas utility 1 6,701 6,446  Other reconciling items 39 70  Total assets – Consumers $ 20,380 $ 19,946  1 Amounts include a portion of Consumers’ other common assets attributable to both the electric and gas utility businesses.

Notes Receivable (Policy)

Notes Receivable (Policy)	9 Months Ended
	Sep. 30, 2017
Notes Receivable [Abstract]
Allowance For Loan Losses Policy	The allowance for loan losses is a valuation allowance to reflect estimated credit losses. The allowance is increased by the provision for loan losses and decreased by loan charge-offs net of recoveries. Management estimates the allowance balance required by taking into consideration historical loan loss experience, the nature and volume of the portfolio, economic conditions, and other factors. Loan losses are charged against the allowance when the loss is confirmed, but no later than the point at which a loan becomes 120 days past due.

Contingencies And Commitments (

Contingencies And Commitments (Tables)	9 Months Ended
	Sep. 30, 2017
Site Contingency [Line Items]
Guarantees	    In Millions  Maximum Carrying  Guarantee Description Issue Date Expiration Date Obligation Amount  CMS Energy, including Consumers  Indemnity obligations from stock and asset sale agreements 1 Various Indefinite $ 153 $ 7  Guarantees 2 Various Indefinite 45 -  Consumers  Guarantee 2 July 2011 Indefinite $ 30 $ -  1 These obligations arose from stock and asset sale agreements under which CMS Energy or a subsidiary of CMS Energy indemnified the purchaser for losses resulting from various matters, primarily claims related to taxes. CMS Energy believes the likelihood of material loss to be remote for the indemnity obligations not recorded as liabilities. 2 At Consumers, this obligation comprises a guarantee provided to the U.S. Department of Energy in connection with a settlement agreement regarding damages resulting from the department’s failure to accept spent nuclear fuel from nuclear power plants formerly owned by Consumers. At CMS Energy, the guarantee obligations comprise Consumers’ guarantee to the U.S. Department of Energy and CMS Energy’s 1994 guarantee of non-recourse revenue bonds issued by Genesee.
Consumers Energy Company [Member]
Site Contingency [Line Items]
Guarantees	    In Millions  Maximum Carrying  Guarantee Description Issue Date Expiration Date Obligation Amount  CMS Energy, including Consumers  Indemnity obligations from stock and asset sale agreements 1 Various Indefinite $ 153 $ 7  Guarantees 2 Various Indefinite 45 -  Consumers  Guarantee 2 July 2011 Indefinite $ 30 $ -  1 These obligations arose from stock and asset sale agreements under which CMS Energy or a subsidiary of CMS Energy indemnified the purchaser for losses resulting from various matters, primarily claims related to taxes. CMS Energy believes the likelihood of material loss to be remote for the indemnity obligations not recorded as liabilities. 2 At Consumers, this obligation comprises a guarantee provided to the U.S. Department of Energy in connection with a settlement agreement regarding damages resulting from the department’s failure to accept spent nuclear fuel from nuclear power plants formerly owned by Consumers. At CMS Energy, the guarantee obligations comprise Consumers’ guarantee to the U.S. Department of Energy and CMS Energy’s 1994 guarantee of non-recourse revenue bonds issued by Genesee.
Bay Harbor [Member]
Site Contingency [Line Items]
Expected Remediation Cost By Year	   In Millions  2017 2018 2019 2020 2021 2022  CMS Energy  Long-term liquid disposal and operating and maintenance costs $ 1 $ 4 $ 4 $ 4 $ 4 $ 4 
Gas Utility [Member] | Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Site Contingency [Line Items]
Expected Remediation Cost By Year	   In Millions  2017 2018 2019 2020 2021 2022  Consumers  Remediation and other response activity costs $ 8 $ 16 $ 18 $ 10 $ 18 $ 7 

Financings And Capitalization (

Financings And Capitalization (Tables)	9 Months Ended
	Sep. 30, 2017
Major Long-Term Debt Transactions	   Principal (In Millions) Interest Rate Issue/Retirement Date Maturity Date  Debt issuances  CMS Energy, parent only  Senior notes $ 350 3.450 % February 2017 August 2027  Total CMS Energy, parent only $ 350  Consumers  First mortgage bonds $ 350 3.950 % February 2017 July 2047  First mortgage bonds 1 40 3.180 September 2017 September 2032  First mortgage bonds 1 125 3.520 September 2017 September 2037  First mortgage bonds 1 20 3.860 September 2017 September 2052  Total Consumers $ 535  Total CMS Energy $ 885  Debt retirements  Consumers  First mortgage bonds $ 250 5.150 % February 2017 February 2017  Senior notes 180 6.875 September 2017 March 2018  Total Consumers $ 430  Total CMS Energy $ 430  1 These first mortgage bonds were issued in a September private placement under a bond purchase agreement executed in August. Under the agreement, Consumers will issue an additional $300 million of first mortgage bonds in a second private placement in November, consisting of $60 million of 3.18 -percent first mortgage bonds due 2032 , $210 million of 3.52 -percent first mortgage bonds due 2037 , and $30 million of 3.86 -percent first mortgage bonds due 2052 .
Revolving Credit Facilities	   In Millions  Expiration Date Amount of Facility Amount Borrowed Letters of Credit Outstanding Amount Available  CMS Energy, parent only  May 27, 2022 1,2 $ 550 $ - $ 1 $ 549  Consumers  May 27, 2022 2,3 $ 650 $ - $ 7 $ 643  November 23, 2018 3 250 - - 250  September 9, 2019 3,4 30 - 30 -  1 During the nine months ended September 30, 2017 , CMS Energy’s average borrowings totaled $28 million with a weighted-average interest rate of 2.02 percent. Obligations under this facility are secured by Consumers common stock. 2 In May 2017, the expiration date of this revolving credit agreement was extended from May 2021 to May 2022. 3 Obligations under this facility are secured by first mortgage bonds of Consumers. 4 In June 2017, the expiration date of this letter of credit reimbursement agreement was extended from May 2018 to September 2019.
Issuance Of Common Stock	   Number of Shares Issued Average Price per Share Net Proceeds (In Millions)  June 2017 1,494,371 $ 47.31 $ 70 
Consumers Energy Company [Member]
Major Long-Term Debt Transactions	   Principal (In Millions) Interest Rate Issue/Retirement Date Maturity Date  Debt issuances  CMS Energy, parent only  Senior notes $ 350 3.450 % February 2017 August 2027  Total CMS Energy, parent only $ 350  Consumers  First mortgage bonds $ 350 3.950 % February 2017 July 2047  First mortgage bonds 1 40 3.180 September 2017 September 2032  First mortgage bonds 1 125 3.520 September 2017 September 2037  First mortgage bonds 1 20 3.860 September 2017 September 2052  Total Consumers $ 535  Total CMS Energy $ 885  Debt retirements  Consumers  First mortgage bonds $ 250 5.150 % February 2017 February 2017  Senior notes 180 6.875 September 2017 March 2018  Total Consumers $ 430  Total CMS Energy $ 430  1 These first mortgage bonds were issued in a September private placement under a bond purchase agreement executed in August. Under the agreement, Consumers will issue an additional $300 million of first mortgage bonds in a second private placement in November, consisting of $60 million of 3.18 -percent first mortgage bonds due 2032 , $210 million of 3.52 -percent first mortgage bonds due 2037 , and $30 million of 3.86 -percent first mortgage bonds due 2052 .
Revolving Credit Facilities	   In Millions  Expiration Date Amount of Facility Amount Borrowed Letters of Credit Outstanding Amount Available  CMS Energy, parent only  May 27, 2022 1,2 $ 550 $ - $ 1 $ 549  Consumers  May 27, 2022 2,3 $ 650 $ - $ 7 $ 643  November 23, 2018 3 250 - - 250  September 9, 2019 3,4 30 - 30 -  1 During the nine months ended September 30, 2017 , CMS Energy’s average borrowings totaled $28 million with a weighted-average interest rate of 2.02 percent. Obligations under this facility are secured by Consumers common stock. 2 In May 2017, the expiration date of this revolving credit agreement was extended from May 2021 to May 2022. 3 Obligations under this facility are secured by first mortgage bonds of Consumers. 4 In June 2017, the expiration date of this letter of credit reimbursement agreement was extended from May 2018 to September 2019.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Assets And Liabilities Measured At Fair Value On A Recurring Basis	   In Millions  CMS Energy, including Consumers Consumers  September 30 December 31 September 30 December 31  2017 2016 2017 2016  Assets 1  Cash equivalents $ 21 $ 44 $ - $ -  Restricted cash equivalents 27 19 27 19  CMS Energy common stock - - 21 33  Nonqualified deferred compensation plan assets 13 12 9 8  DB SERP  Cash equivalents 4 3 3 2  Mutual funds 145 141 105 102  Derivative instruments  Commodity contracts 2 1 2 1  Total $ 212 $ 220 $ 167 $ 165  Liabilities 1  Nonqualified deferred compensation plan liabilities $ 13 $ 12 $ 9 $ 8  Derivative instruments  Commodity contracts 1 - 1 -  Total $ 14 $ 12 $ 10 $ 8  1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3.
Consumers Energy Company [Member]
Assets And Liabilities Measured At Fair Value On A Recurring Basis	   In Millions  CMS Energy, including Consumers Consumers  September 30 December 31 September 30 December 31  2017 2016 2017 2016  Assets 1  Cash equivalents $ 21 $ 44 $ - $ -  Restricted cash equivalents 27 19 27 19  CMS Energy common stock - - 21 33  Nonqualified deferred compensation plan assets 13 12 9 8  DB SERP  Cash equivalents 4 3 3 2  Mutual funds 145 141 105 102  Derivative instruments  Commodity contracts 2 1 2 1  Total $ 212 $ 220 $ 167 $ 165  Liabilities 1  Nonqualified deferred compensation plan liabilities $ 13 $ 12 $ 9 $ 8  Derivative instruments  Commodity contracts 1 - 1 -  Total $ 14 $ 12 $ 10 $ 8  1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3.

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Schedule Of Carrying Amounts And Fair Values Of Financial Instruments	   In Millions  September 30, 2017 December 31, 2016  Fair Value Fair Value  Carrying Level Carrying Level  Amount Total 1 2 3 Amount Total 1 2 3  CMS Energy, including Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ 22 $ 22 $ - $ - $ 22  Notes receivable 2 1,382 1,479 - - 1,479 1,326 1,415 - - 1,415  Securities held to maturity 16 16 - 16 - 13 13 - 13 -  Liabilities  Long-term debt 3 9,983 10,484 - 9,331 1,153 9,504 9,953 - 8,990 963  Long-term payables 4 18 18 - - 18 17 17 - - 17  Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ 22 $ 22 $ - $ - $ 22  Notes receivable 5 46 46 - - 46 45 45 - - 45  Liabilities  Long-term debt 6 5,718 6,032 - 4,879 1,153 5,628 5,903 - 4,940 963  1 Includes current accounts receivable of $14 million at September 30, 2 017 and $12 million at December 31, 20 16 . 2 Includes current portion of notes receivable of $228 million at September 30, 2 017 and $ 219 million at December 31, 20 16 . 3 Includes current portion of long-term debt of $959 million at September 30, 2 017 and $ 864 million at December 31, 20 16 . 4 Includes current portion of long-term payables of $1 million at September 30, 2 017 and December 31, 20 16 . 5 Includes current portion of notes receivable of $30 million at September 30, 2 017 and $29 million at December 31, 20 16 . 6 Includes current portion of long-term debt of $443 million at September 30, 2 017 and $ 375 million at December 31, 20 16 .
Schedule Of Investment Securities	   In Millions  September 30, 2017 December 31, 2016  Unrealized Unrealized Fair Unrealized Unrealized Fair  Cost Gains Losses Value Cost Gains Losses Value  CMS Energy, including Consumers  Available for sale  DB SERP  Mutual funds $ 142 $ 3 $ - $ 145 $ 141 $ - $ - $ 141  Held to maturity  Debt securities 16 - - 16 13 - - 13  Consumers  Available for sale  DB SERP  Mutual funds $ 103 $ 2 $ - $ 105 $ 102 $ - $ - $ 102  CMS Energy common stock 2 19 - 21 4 29 - 33 
Consumers Energy Company [Member]
Schedule Of Carrying Amounts And Fair Values Of Financial Instruments	   In Millions  September 30, 2017 December 31, 2016  Fair Value Fair Value  Carrying Level Carrying Level  Amount Total 1 2 3 Amount Total 1 2 3  CMS Energy, including Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ 22 $ 22 $ - $ - $ 22  Notes receivable 2 1,382 1,479 - - 1,479 1,326 1,415 - - 1,415  Securities held to maturity 16 16 - 16 - 13 13 - 13 -  Liabilities  Long-term debt 3 9,983 10,484 - 9,331 1,153 9,504 9,953 - 8,990 963  Long-term payables 4 18 18 - - 18 17 17 - - 17  Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ 22 $ 22 $ - $ - $ 22  Notes receivable 5 46 46 - - 46 45 45 - - 45  Liabilities  Long-term debt 6 5,718 6,032 - 4,879 1,153 5,628 5,903 - 4,940 963  1 Includes current accounts receivable of $14 million at September 30, 2 017 and $12 million at December 31, 20 16 . 2 Includes current portion of notes receivable of $228 million at September 30, 2 017 and $ 219 million at December 31, 20 16 . 3 Includes current portion of long-term debt of $959 million at September 30, 2 017 and $ 864 million at December 31, 20 16 . 4 Includes current portion of long-term payables of $1 million at September 30, 2 017 and December 31, 20 16 . 5 Includes current portion of notes receivable of $30 million at September 30, 2 017 and $29 million at December 31, 20 16 . 6 Includes current portion of long-term debt of $443 million at September 30, 2 017 and $ 375 million at December 31, 20 16 .
Schedule Of Investment Securities	   In Millions  September 30, 2017 December 31, 2016  Unrealized Unrealized Fair Unrealized Unrealized Fair  Cost Gains Losses Value Cost Gains Losses Value  CMS Energy, including Consumers  Available for sale  DB SERP  Mutual funds $ 142 $ 3 $ - $ 145 $ 141 $ - $ - $ 141  Held to maturity  Debt securities 16 - - 16 13 - - 13  Consumers  Available for sale  DB SERP  Mutual funds $ 103 $ 2 $ - $ 105 $ 102 $ - $ - $ 102  CMS Energy common stock 2 19 - 21 4 29 - 33 

Notes Receivable (Tables)

Notes Receivable (Tables)	9 Months Ended
	Sep. 30, 2017
Schedule Of Current And Non-Current Notes Receivable	   In Millions  September 30, 2017 December 31, 2016  CMS Energy, including Consumers  Current  EnerBank notes receivable, net of allowance for loan losses $ 167 $ 151  EnerBank notes receivable held for sale 31 39  Michigan tax settlement 30 29  Non-current  EnerBank notes receivable 1,134 1,088  Michigan tax settlement 20 19  Total notes receivable $ 1,382 $ 1,326  Consumers  Current  Michigan tax settlement $ 30 $ 29  Non-current  Michigan tax settlement 16 16  Total notes receivable $ 46 $ 45 
Consumers Energy Company [Member]
Schedule Of Current And Non-Current Notes Receivable	   In Millions  September 30, 2017 December 31, 2016  CMS Energy, including Consumers  Current  EnerBank notes receivable, net of allowance for loan losses $ 167 $ 151  EnerBank notes receivable held for sale 31 39  Michigan tax settlement 30 29  Non-current  EnerBank notes receivable 1,134 1,088  Michigan tax settlement 20 19  Total notes receivable $ 1,382 $ 1,326  Consumers  Current  Michigan tax settlement $ 30 $ 29  Non-current  Michigan tax settlement 16 16  Total notes receivable $ 46 $ 45 

Retirement Benefits (Tables)

Retirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Net Benefit Costs	   In Millions  DB Pension Plan OPEB Plan  Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016 2017 2016 2017 2016  CMS Energy, including Consumers  Net periodic cost (credit)  Service cost $ 12 $ 10 $ 34 $ 31 $ 5 $ 5 $ 15 $ 14  Interest cost 23 21 67 64 13 12 39 35  Expected return on plan assets (39) (36) (115) (110) (22) (22) (67) (65)  Amortization of:  Net loss 20 17 60 52 7 5 23 16  Prior service cost (credit) 1 1 3 3 (8) (10) (26) (31)  Net periodic cost (credit) $ 17 $ 13 $ 49 $ 40 $ (5) $ (10) $ (16) $ (31)  Consumers  Net periodic cost (credit)  Service cost $ 11 $ 11 $ 33 $ 31 $ 5 $ 4 $ 14 $ 13  Interest cost 22 20 65 62 12 12 38 34  Expected return on plan assets (38) (35) (112) (107) (21) (20) (63) (60)  Amortization of:  Net loss 19 16 58 50 8 5 24 16  Prior service cost (credit) 1 1 3 3 (8) (10) (25) (30)  Net periodic cost (credit) $ 15 $ 13 $ 47 $ 39 $ (4) $ (9) $ (12) $ (27) 
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Net Benefit Costs	   In Millions  DB Pension Plan OPEB Plan  Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016 2017 2016 2017 2016  CMS Energy, including Consumers  Net periodic cost (credit)  Service cost $ 12 $ 10 $ 34 $ 31 $ 5 $ 5 $ 15 $ 14  Interest cost 23 21 67 64 13 12 39 35  Expected return on plan assets (39) (36) (115) (110) (22) (22) (67) (65)  Amortization of:  Net loss 20 17 60 52 7 5 23 16  Prior service cost (credit) 1 1 3 3 (8) (10) (26) (31)  Net periodic cost (credit) $ 17 $ 13 $ 49 $ 40 $ (5) $ (10) $ (16) $ (31)  Consumers  Net periodic cost (credit)  Service cost $ 11 $ 11 $ 33 $ 31 $ 5 $ 4 $ 14 $ 13  Interest cost 22 20 65 62 12 12 38 34  Expected return on plan assets (38) (35) (112) (107) (21) (20) (63) (60)  Amortization of:  Net loss 19 16 58 50 8 5 24 16  Prior service cost (credit) 1 1 3 3 (8) (10) (25) (30)  Net periodic cost (credit) $ 15 $ 13 $ 47 $ 39 $ (4) $ (9) $ (12) $ (27) 

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2017
Schedule Of Effective Income Tax Rate Reconciliation	   Nine Months Ended September 30 2017 2016  CMS Energy, including Consumers  U.S. federal income tax rate 35.0 % 35.0 %  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 1 2.3 4.2  Accelerated flow-through of regulatory tax benefits 2 (4.3) (4.7)  Employee share-based awards (0.9) (0.8)  Other, net (2.0) (1.4)  Effective tax rate 30.1 % 32.3 %  Consumers  U.S. federal income tax rate 35.0 % 35.0 %  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 1 2.3 4.6  Accelerated flow-through of regulatory tax benefits 2 (3.9) (4.0)  Employee share-based awards (0.8) (0.7)  Other, net (2.3) (1.2)  Effective tax rate 30.3 % 33.7 %  1 In September 2017, CMS Energy completed the evaluation of its methodology for the state apportionment of Consumers’ electricity sales to MISO, taking into account recent state tax law developments in the electric utility sector. As a result, CMS Energy intends to amend state income tax filings for 2013 through 2016 to seek a refund of taxes previously paid. To recognize the anticipated refund and the impact of the expected lower effective tax rate on their deferred state tax liabilities, CMS Energy recorded a $15 million income tax benefit and Consumers recorded a $16 million income tax benefit in September 2017. Both amounts are net of reserves for uncertain tax positions. For the nine months ended September 30, 2017, the impact of the benefit was a 2.3 percentage point reduction to CMS Energy’s effective tax rate and a 2.2 percentage point reduction to Consumers’ effective tax rate. 2 Since 2014, Consumers has followed a regulatory treatment ordered by the MPSC that accelerates the return of certain income tax benefits to customers. This change, which also accelerates Consumers’ recognition of the income tax benefits, reduced Consumers’ income tax expense by $28 million for the nine months ended September 30, 2017 and by $30 million for the nine months ended September 30, 2016.
Consumers Energy Company [Member]
Schedule Of Effective Income Tax Rate Reconciliation	   Nine Months Ended September 30 2017 2016  CMS Energy, including Consumers  U.S. federal income tax rate 35.0 % 35.0 %  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 1 2.3 4.2  Accelerated flow-through of regulatory tax benefits 2 (4.3) (4.7)  Employee share-based awards (0.9) (0.8)  Other, net (2.0) (1.4)  Effective tax rate 30.1 % 32.3 %  Consumers  U.S. federal income tax rate 35.0 % 35.0 %  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 1 2.3 4.6  Accelerated flow-through of regulatory tax benefits 2 (3.9) (4.0)  Employee share-based awards (0.8) (0.7)  Other, net (2.3) (1.2)  Effective tax rate 30.3 % 33.7 %  1 In September 2017, CMS Energy completed the evaluation of its methodology for the state apportionment of Consumers’ electricity sales to MISO, taking into account recent state tax law developments in the electric utility sector. As a result, CMS Energy intends to amend state income tax filings for 2013 through 2016 to seek a refund of taxes previously paid. To recognize the anticipated refund and the impact of the expected lower effective tax rate on their deferred state tax liabilities, CMS Energy recorded a $15 million income tax benefit and Consumers recorded a $16 million income tax benefit in September 2017. Both amounts are net of reserves for uncertain tax positions. For the nine months ended September 30, 2017, the impact of the benefit was a 2.3 percentage point reduction to CMS Energy’s effective tax rate and a 2.2 percentage point reduction to Consumers’ effective tax rate. 2 Since 2014, Consumers has followed a regulatory treatment ordered by the MPSC that accelerates the return of certain income tax benefits to customers. This change, which also accelerates Consumers’ recognition of the income tax benefits, reduced Consumers’ income tax expense by $28 million for the nine months ended September 30, 2017 and by $30 million for the nine months ended September 30, 2016.

Earnings Per Share - CMS Ener29

Earnings Per Share - CMS Energy (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share - CMS Energy [Abstract]
Basic And Diluted EPS Computations	   In Millions, Except Per Share Amounts  Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016  Income available to common stockholders  Net income $ 172 $ 186 $ 464 $ 475  Less income attributable to noncontrolling interests - - 1 1  Net income available to common stockholders – basic and diluted $ 172 $ 186 $ 463 $ 474  Average common shares outstanding  Weighted-average shares – basic 280.8 278.2 279.8 277.7  Add dilutive nonvested stock awards 0.8 1.0 0.8 1.1  Weighted-average shares – diluted 281.6 279.2 280.6 278.8  Net income per average common share available to common stockholders  Basic $ 0.61 $ 0.67 $ 1.65 $ 1.71  Diluted 0.61 0.67 1.65 1.70 

Cash And Cash Equivalents (Tabl

Cash And Cash Equivalents (Tables)	9 Months Ended
	Sep. 30, 2017
Schedule Of Cash And Cash Equivalents, Including Restricted Amounts	   In Millions  September 30 December 31  2017 2016  CMS Energy, including Consumers  Cash and cash equivalents $ 142 $ 235  Restricted cash and cash equivalents 27 19  Other non-current assets 4 3  Cash and cash equivalents, including restricted amounts $ 173 $ 257  Consumers  Cash and cash equivalents $ 55 $ 131  Restricted cash and cash equivalents 27 19  Other non-current assets 3 2  Cash and cash equivalents, including restricted amounts $ 85 $ 152 
Schedule Of Restricted Cash Balances	   In Millions  Nine Months Ended September 30 2016  CMS Energy, including Consumers  Change in:  Net cash used in investing activities $ 7  Cash and cash equivalents, including restricted amounts, end of period 29  Consumers  Change in:  Net cash used in investing activities $ 8  Cash and cash equivalents, including restricted amounts, end of period 29 
Consumers Energy Company [Member]
Schedule Of Cash And Cash Equivalents, Including Restricted Amounts	   In Millions  September 30 December 31  2017 2016  CMS Energy, including Consumers  Cash and cash equivalents $ 142 $ 235  Restricted cash and cash equivalents 27 19  Other non-current assets 4 3  Cash and cash equivalents, including restricted amounts $ 173 $ 257  Consumers  Cash and cash equivalents $ 55 $ 131  Restricted cash and cash equivalents 27 19  Other non-current assets 3 2  Cash and cash equivalents, including restricted amounts $ 85 $ 152 
Schedule Of Restricted Cash Balances	   In Millions  Nine Months Ended September 30 2016  CMS Energy, including Consumers  Change in:  Net cash used in investing activities $ 7  Cash and cash equivalents, including restricted amounts, end of period 29  Consumers  Change in:  Net cash used in investing activities $ 8  Cash and cash equivalents, including restricted amounts, end of period 29 

Reportable Segments (Tables)

Reportable Segments (Tables)	9 Months Ended
	Sep. 30, 2017
Schedule Of Financial Information By Reportable Segments	   In Millions  Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016  CMS Energy, including Consumers  Operating revenue  Electric utility $ 1,247 $ 1,313 $ 3,360 $ 3,348  Gas utility 190 185 1,176 1,166  Enterprises 58 59 172 156  Other reconciling items 32 30 97 89  Total operating revenue – CMS Energy $ 1,527 $ 1,587 $ 4,805 $ 4,759  Consumers  Operating revenue  Electric utility $ 1,247 $ 1,313 $ 3,360 $ 3,348  Gas utility 190 185 1,176 1,166  Total operating revenue – Consumers $ 1,437 $ 1,498 $ 4,536 $ 4,514  CMS Energy, including Consumers  Net income (loss) available to common stockholders  Electric utility $ 176 $ 191 $ 394 $ 395  Gas utility 5 3 101 102  Enterprises 8 8 27 17  Other reconciling items (17) (16) (59) (40)  Total net income available to common stockholders – CMS Energy $ 172 $ 186 $ 463 $ 474  Consumers  Net income available to common stockholder  Electric utility $ 176 $ 191 $ 394 $ 395  Gas utility 5 3 101 102  Other reconciling items - 1 - 1  Total net income available to common stockholder – Consumers $ 181 $ 195 $ 495 $ 498     In Millions  September 30, 2017 December 31, 2016  CMS Energy, including Consumers  Plant, property, and equipment, gross  Electric utility 1 $ 15,056 $ 14,540  Gas utility 1 6,713 6,283  Enterprises 164 157  Other reconciling items 33 30  Total plant, property, and equipment, gross – CMS Energy $ 21,966 $ 21,010  Consumers  Plant, property, and equipment, gross  Electric utility 1 $ 15,056 $ 14,540  Gas utility 1 6,713 6,283  Other reconciling items 15 15  Total plant, property, and equipment, gross – Consumers $ 21,784 $ 20,838  CMS Energy, including Consumers  Total assets  Electric utility 1 $ 13,639 $ 13,429  Gas utility 1 6,701 6,446  Enterprises 280 269  Other reconciling items 1,500 1,478  Total assets – CMS Energy $ 22,120 $ 21,622  Consumers  Total assets  Electric utility 1 $ 13,640 $ 13,430  Gas utility 1 6,701 6,446  Other reconciling items 39 70  Total assets – Consumers $ 20,380 $ 19,946  1 Amounts include a portion of Consumers’ other common assets attributable to both the electric and gas utility businesses.
Consumers Energy Company [Member]
Schedule Of Financial Information By Reportable Segments	   In Millions  Three Months Ended Nine Months Ended  September 30 2017 2016 2017 2016  CMS Energy, including Consumers  Operating revenue  Electric utility $ 1,247 $ 1,313 $ 3,360 $ 3,348  Gas utility 190 185 1,176 1,166  Enterprises 58 59 172 156  Other reconciling items 32 30 97 89  Total operating revenue – CMS Energy $ 1,527 $ 1,587 $ 4,805 $ 4,759  Consumers  Operating revenue  Electric utility $ 1,247 $ 1,313 $ 3,360 $ 3,348  Gas utility 190 185 1,176 1,166  Total operating revenue – Consumers $ 1,437 $ 1,498 $ 4,536 $ 4,514  CMS Energy, including Consumers  Net income (loss) available to common stockholders  Electric utility $ 176 $ 191 $ 394 $ 395  Gas utility 5 3 101 102  Enterprises 8 8 27 17  Other reconciling items (17) (16) (59) (40)  Total net income available to common stockholders – CMS Energy $ 172 $ 186 $ 463 $ 474  Consumers  Net income available to common stockholder  Electric utility $ 176 $ 191 $ 394 $ 395  Gas utility 5 3 101 102  Other reconciling items - 1 - 1  Total net income available to common stockholder – Consumers $ 181 $ 195 $ 495 $ 498     In Millions  September 30, 2017 December 31, 2016  CMS Energy, including Consumers  Plant, property, and equipment, gross  Electric utility 1 $ 15,056 $ 14,540  Gas utility 1 6,713 6,283  Enterprises 164 157  Other reconciling items 33 30  Total plant, property, and equipment, gross – CMS Energy $ 21,966 $ 21,010  Consumers  Plant, property, and equipment, gross  Electric utility 1 $ 15,056 $ 14,540  Gas utility 1 6,713 6,283  Other reconciling items 15 15  Total plant, property, and equipment, gross – Consumers $ 21,784 $ 20,838  CMS Energy, including Consumers  Total assets  Electric utility 1 $ 13,639 $ 13,429  Gas utility 1 6,701 6,446  Enterprises 280 269  Other reconciling items 1,500 1,478  Total assets – CMS Energy $ 22,120 $ 21,622  Consumers  Total assets  Electric utility 1 $ 13,640 $ 13,430  Gas utility 1 6,701 6,446  Other reconciling items 39 70  Total assets – Consumers $ 20,380 $ 19,946  1 Amounts include a portion of Consumers’ other common assets attributable to both the electric and gas utility businesses.

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended							3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2017	Mar. 31, 2017	Feb. 28, 2017	Jan. 31, 2017	Sep. 30, 2016	Aug. 31, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Oct. 31, 2017
Public Utilities, General Disclosures [Line Items]
Regulatory liability current								$ 85		$ 85		$ 95
Accrued rate refunds								35		35		21
Revenue								1,527	$ 1,587	4,805	$ 4,759
Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability current								85		85		95
Accrued rate refunds								35		35		21
Revenue								1,437	$ 1,498	4,536	$ 4,514
2016 Electric Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested							$ 225
Rate of return on equity requested							10.70%
Annual rate increase self-implemented					$ 170
Annual rate increase authorized			$ 113
Rate of return on equity authorized			10.10%
2016 Electric Rate Case [Member] | Revenue Subject To Refund [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability current								17		17
2016 Electric Rate Case [Member] | Revenue Subject To Refund [Member] | Consumers Energy Company [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability current													$ 17
Gas Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested						$ 90
Amended Annual Rate Increase Request		$ 80
Rate of return on equity requested						10.60%
Investment recovery, 2018	$ 18
Investment recovery, 2019	18
Annual rate increase self-implemented				$ 20
Annual rate increase authorized	$ 29
Energy Optimization [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Authorized recovery/collection								$ 18		$ 18
Revenue												$ 18
Depreciation Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase authorized		$ (3)
FERC Transmission Order [Member] | Consumers Energy Company [Member] | Electric Transmission [Member]
Public Utilities, General Disclosures [Line Items]
Rate of return on equity authorized					10.32%	12.38%
Power Supply Cost Recover (PSCR) [Member] | Consumers Energy Company [Member] | Electric Transmission [Member]
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds			$ 28

Contingencies And Commitments33

Contingencies And Commitments (Contingencies And Commitments) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)lawsuititem	Dec. 31, 2016USD ($)
Loss Contingencies [Line Items]
Number of lawsuits settled | lawsuit	3
Regulatory assets	$ 2,038	$ 2,091
Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Regulatory assets	2,038	$ 2,091
Bay Harbor [Member]
Loss Contingencies [Line Items]
Demand for payment by USEPA	8
Accrual for environmental loss contingencies	$ 49
Discounted projected costs rate	4.34%
Remaining undiscounted obligation amount	$ 62
Accrual for environmental loss contingencies, inflation rate	1.00%
Electric Utility [Member] | NREPA [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 3
Electric Utility [Member] | NREPA [Member] | Minimum [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Remediation and other response activity costs	3
Electric Utility [Member] | NREPA [Member] | Maximum [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Remediation and other response activity costs	4
Electric Utility [Member] | CERCLA Liability [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	3
Electric Utility [Member] | CERCLA Liability [Member] | Minimum [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Remediation and other response activity costs	3
Electric Utility [Member] | CERCLA Liability [Member] | Maximum [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Remediation and other response activity costs	8
Gas Utility [Member] | NREPA [Member] | Maximum [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	1
Remediation and other response activity costs	3
Gas Utility [Member] | Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 93
Discounted projected costs rate	2.57%
Remaining undiscounted obligation amount	$ 104
Number of former MGPs | item	23
Regulatory assets	$ 141
Authorized recovery, collection period	10 years
Accrual for environmental loss contingencies, inflation rate	2.50%
Equatorial Guinea Tax Claim [Member]
Loss Contingencies [Line Items]
Foreign government tax claim on sale	$ 152
Class Action Lawsuits [Member]
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit	4
Individual Lawsuits [Member]
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit	1

Contingencies And Commitments34

Contingencies And Commitments (Expected Remediation Cost By Year) (Details) $ in Millions	Sep. 30, 2017USD ($)
Bay Harbor [Member]
Site Contingency [Line Items]
Undiscounted amount due within one year	$ 1
Undiscounted amount due within two year	4
Undiscounted amount due within third year	4
Undiscounted amount due within fourth year	4
Undiscounted amount due within five year	4
Undiscounted amount due within six year	4
Gas Utility [Member] | Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Site Contingency [Line Items]
Undiscounted amount due within one year	8
Undiscounted amount due within two year	16
Undiscounted amount due within third year	18
Undiscounted amount due within fourth year	10
Undiscounted amount due within five year	18
Undiscounted amount due within six year	$ 7

Contingencies And Commitments35

Contingencies And Commitments (Guarantees) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Guarantees [Member]
Guarantees And Other Contingencies [Line Items]
Guarantee Description	Guarantees	[1]
Expiration Date	Indefinite	[1]
Maximum obligation	$ 45	[1]
Guarantees [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Guarantee Description	Guarantee	[1]
Expiration Date	Indefinite	[1]
Maximum obligation	$ 30	[1]
Indemnity Obligations From Stock And Asset Sales Agreements [Member]
Guarantees And Other Contingencies [Line Items]
Guarantee Description	Indemnity obligations from stock and asset sales agreements	[2]
Expiration Date	Indefinite	[2]
Maximum obligation	$ 153	[2]
Carrying Amount	7	[2]
Tax And Other Indemnity Obligations [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Carrying Amount	$ 1
[1]	At Consumers, this obligation comprises a guarantee provided to the U.S. Department of Energy in connection with a settlement agreement regarding damages resulting from the department's failure to accept spent nuclear fuel from nuclear power plants formerly owned by Consumers. At CMS Energy, the guarantee obligations comprise Consumers' guarantee to the U.S. Department of Energy and CMS Energy's 1994 guarantee of non-recourse revenue bonds issued by Genesee.
[2]	These obligations arose from stock and asset sale agreements under which CMS Energy or a subsidiary of CMS Energy indemnified the purchaser for losses resulting from various matters, primarily claims related to taxes. CMS Energy believes the likelihood of material loss to be remote for the indemnity obligations not recorded as liabilities.

Financings And Capitalization36

Financings And Capitalization (Narrative) (Details) - USD ($)	1 Months Ended	9 Months Ended
	Oct. 25, 2017	Sep. 30, 2017
Financing And Capitalization [Line Items]
Debt issuance		$ 885,000,000
Debt retirement, principal		430,000,000
Unrestricted retained earnings		4,500,000,000
Common stock dividends from Consumers		347,000,000
Term Loan [Member]
Financing And Capitalization [Line Items]
Debt issuance		$ 180,000,000
Debt instrument, extension term		1 year
CMS Energy [Member]
Financing And Capitalization [Line Items]
Debt issuance		$ 350,000,000
Consumers Energy Company [Member]
Financing And Capitalization [Line Items]
Debt issuance		535,000,000
Debt retirement, principal		430,000,000
Unrestricted retained earnings		1,100,000,000
Consumers Energy Company [Member] | Commercial Paper [Member]
Financing And Capitalization [Line Items]
Short-term debt, authorized borrowings		500,000,000
Short-term borrowings outstanding		$ 230,000,000
Consumers Energy Company [Member] | FMB's 3.21% Due 2017 [Member] | Subsequent Event [Member]
Financing And Capitalization [Line Items]
Debt retirement, principal	$ 100,000,000
Interest rate	3.21%

Financings And Capitalization37

Financings And Capitalization (Major Long-Term Debt Transactions) (Details) - USD ($)		1 Months Ended	9 Months Ended
		Nov. 30, 2017	Sep. 30, 2017
Debt Instrument [Line Items]
Principal Balance			$ 885,000,000
Debt retirement, principal			430,000,000
CMS Energy [Member]
Debt Instrument [Line Items]
Principal Balance			350,000,000
Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance			535,000,000
Debt retirement, principal			430,000,000
Senior Notes 3.450% Due August 2027 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Principal Balance			$ 350,000,000
Interest rate			3.45%
Debt issuance date			February 2017
Maturity date			August 2,027
FMB's 3.950% Due July 2047 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance			$ 350,000,000
Interest rate			3.95%
Debt issuance date			February 2017
Maturity date			July 2,047
FMB's 3.180% Due September 2032 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance	[1]		$ 40,000,000
Interest rate	[1]		3.18%
Debt issuance date	[1]		September 2017
Maturity date	[1]		September 2,032
FMB's 3.520% Due September 2037 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance	[1]		$ 125,000,000
Interest rate	[1]		3.52%
Debt issuance date	[1]		September 2017
Maturity date	[1]		September 2,037
FMB's 3.860% Due September 2052 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance	[1]		$ 20,000,000
Interest rate	[1]		3.86%
Debt issuance date	[1]		September 2017
Maturity date	[1]		September 2,052
FMB's 5.150% Due February 2017 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Debt retirement, principal			$ 250,000,000
Interest rate			5.15%
Debt retirement date			February 2017
Maturity date			February 2,017
Senior Notes 6.875% Due March 2018 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Debt retirement, principal			$ 180,000,000
Interest rate			6.875%
Debt issuance date			September 2,017
Maturity date			March 2,018
Scenario, Forecast [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance		$ 300,000,000
Scenario, Forecast [Member] | FMB's 3.180% Due September 2032 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance		$ 60,000,000
Interest rate		3.18%
Maturity date		2,032
Scenario, Forecast [Member] | FMB's 3.520% Due September 2037 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance		$ 210,000,000
Interest rate		3.52%
Maturity date		2,037
Scenario, Forecast [Member] | FMB's 3.860% Due September 2052 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance		$ 30,000,000
Interest rate		3.86%
Maturity date		2,052
[1]	These first mortgage bonds were issued in a September private placement under a bond purchase agreement executed in August. Under the agreement, Consumers will issue an additional $300 million of first mortgage bonds in a second private placement in November, consisting of $60 million of 3.18-percent first mortgage bonds due 2032, $210 million of 3.52-percent first mortgage bonds due 2037, and $30 million of 3.86-percent first mortgage bonds due 2052.

Financings And Capitalization38

Financings And Capitalization (Revolving Credit Facilities) (Details)	9 Months Ended
	Sep. 30, 2017USD ($)
Revolving Credit Facilities May 27, 2022 [Member] | CMS Energy [Member]
Line of Credit Facility [Line Items]
Expiration Date	May 27, 2022	[1],[2]
Amount of Facility	$ 550,000,000	[1],[2]
Letters of Credit Outstanding	1,000,000	[1],[2]
Amount Available	549,000,000	[1],[2]
Average borrowings	$ 28,000,000
Weighted average interest rate	2.02%
Revolving Credit Facilities May 27, 2022 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	May 27, 2022	[2],[3]
Amount of Facility	$ 650,000,000	[2],[3]
Letters of Credit Outstanding	7,000,000	[2],[3]
Amount Available	$ 643,000,000	[2],[3]
Revolving Credit Facilities November 23, 2018 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	Nov. 23, 2018	[3]
Amount of Facility	$ 250,000,000	[3]
Amount Available	$ 250,000,000	[3]
Revolving Credit Facilities September 9, 2019 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	Sep. 9, 2019	[3],[4]
Amount of Facility	$ 30,000,000	[3],[4]
Letters of Credit Outstanding	$ 30,000,000	[3],[4]
[1]	During the nine months ended September 30, 2017, CMS Energy's average borrowings totaled $28 million with a weighted-average interest rate of 2.02 percent. Obligations under this facility are secured by Consumers common stock.
[2]	In May 2017, the expiration date of this revolving credit agreement was extended from May 2021 to May 2022.
[3]	Obligations under this facility are secured by first mortgage bonds of Consumers.
[4]	In June 2017, the expiration date of this letter of credit reimbursement agreement was extended from May 2018 to September 2019.

Financings And Capitalization39

Financings And Capitalization (Issuance Of Common Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Jun. 30, 2017	Mar. 31, 2017
Financings And Capitalization [Abstract]
Stock Offering Program Maximum Value		$ 100
Number of Shares Issued	1,494,371
Average Price Per Share	$ 47.31
Net Proceeds	$ 70

Fair Value Measurements (Assets

Fair Value Measurements (Assets And Liabilties Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	$ 21	$ 44
Restricted cash equivalents	[1]	27	19
Nonqualified deferred compensation plan assets	[1]	13	12
Commodity contracts	[1]	2	1
Total	[1]	212	220
Nonqualified deferred compensation plan liabilities	[1]	13	12
Commodity contracts	[1]	1
Total	[1]	14	12
Consumers Energy Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash equivalents	[1]	27	19
Nonqualified deferred compensation plan assets	[1]	9	8
Commodity contracts	[1]	2	1
Total	[1]	167	165
Nonqualified deferred compensation plan liabilities	[1]	9	8
Commodity contracts	[1]	1
Total	[1]	10	8
DB SERP [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	4	3
DB SERP [Member] | Consumers Energy Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	3	2
DB SERP [Member] | Mutual Fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale - Fair Value	[1]	145	141
DB SERP [Member] | Mutual Fund [Member] | Consumers Energy Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale - Fair Value	[1]	105	102
CMS Energy Common Stock [Member] | Consumers Energy Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale - Fair Value	[1]	$ 21	$ 33
[1]	All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3.

Financial Instruments (Narrativ

Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Financial Instruments [Line Items]
Portion of long-term debt supported by third-party credit enhancements	$ 103	$ 103
Consumers Energy Company [Member]
Financial Instruments [Line Items]
Portion of long-term debt supported by third-party credit enhancements	$ 103	$ 103

Financial Instruments (Schedule

Financial Instruments (Schedule Of Carrying Amounts And Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and accrued interest receivable		$ 197	$ 180
Other liabilities current		130	199
Current portion of long-term debt		959	864
DIG Note Payable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other liabilities current		1	1
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[1]	22	22
Notes receivable, Fair Value	[2]	1,382	1,326
Securities held to maturity - Fair Value		16	13
Long-term debt, Fair Value	[3]	9,983	9,504
Long-term payables, Fair Value	[4]	18	17
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[1]	22	22
Notes receivable, Fair Value	[2]	1,479	1,415
Securities held to maturity - Fair Value		16	13
Long-term debt, Fair Value	[3]	10,484	9,953
Long-term payables, Fair Value	[4]	18	17
Consumers Energy Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and accrued interest receivable		30	29
Other liabilities current		93	164
Current portion of long-term debt		443	375
Consumers Energy Company [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[1]	22	22
Notes receivable, Fair Value	[5]	46	45
Long-term debt, Fair Value	[6]	5,718	5,628
Consumers Energy Company [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[1]	22	22
Notes receivable, Fair Value	[5]	46	45
Long-term debt, Fair Value	[6]	6,032	5,903
EnerBank [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current notes receivable		228	219
Other Receivables [Member] | Consumers Energy Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts receivable, current		14	12
Fair Value, Inputs, Level 1 [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[1]
Notes receivable, Fair Value	[2]
Securities held to maturity - Fair Value
Long-term debt, Fair Value	[3]
Long-term payables, Fair Value	[4]
Fair Value, Inputs, Level 1 [Member] | Consumers Energy Company [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[1]
Notes receivable, Fair Value	[5]
Long-term debt, Fair Value	[6]
Fair Value, Inputs, Level 2 [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity - Fair Value		16	13
Long-term debt, Fair Value	[3]	9,331	8,990
Fair Value, Inputs, Level 2 [Member] | Consumers Energy Company [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	[6]	4,879	4,940
Fair Value, Inputs, Level 3 [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[1]	22	22
Notes receivable, Fair Value	[2]	1,479	1,415
Long-term debt, Fair Value	[3]	1,153	963
Long-term payables, Fair Value	[4]	18	17
Fair Value, Inputs, Level 3 [Member] | Consumers Energy Company [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[1]	22	22
Notes receivable, Fair Value	[5]	46	45
Long-term debt, Fair Value	[6]	$ 1,153	$ 963
[1]	Includes current accounts receivable of $14 million at September 30, 2017 and $12 million at December 31, 2016.
[2]	Includes current portion of notes receivable of $228 million at September 30, 2017 and $219 million at December 31, 2016.
[3]	Includes current portion of long-term debt of $959 million at September 30, 2017 and $864 million at December 31, 2016.
[4]	Includes current portion of long-term payables of $1 million at September 30, 2017 and December 31, 2016.
[5]	Includes current portion of notes receivable of $30 million at September 30, 2017 and $29 million at December 31, 2016.
[6]	Includes current portion of long-term debt of $443 million at September 30, 2017 and $375 million at December 31, 2016.

Financial Instruments (Schedu43

Financial Instruments (Schedule Of Investment Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debt Securities [Member]
Investment Securities [Line Items]
Held to maturity securities - Cost	$ 16	$ 13
Held to maturity securities - Unrealized Gains
Held to maturity securities - Unrealized Losses
Held to maturity securities - Fair Value	16	13
CMS Energy Common Stock [Member] | Consumers Energy Company [Member]
Investment Securities [Line Items]
Available for sale - Cost	2	4
Available for sale - Unrealized Gains	19	29
Available for sale - Unrealized Losses
Available for sale - Fair Value	21	33
DB SERP [Member] | Mutual Fund [Member]
Investment Securities [Line Items]
Available for sale - Cost	142	141
Available for sale - Unrealized Gains	3
Available for sale - Unrealized Losses
Available for sale - Fair Value	145	141
DB SERP [Member] | Mutual Fund [Member] | Consumers Energy Company [Member]
Investment Securities [Line Items]
Available for sale - Cost	103	102
Available for sale - Unrealized Gains	2
Available for sale - Unrealized Losses
Available for sale - Fair Value	$ 105	$ 102

Notes Receivable (Narrative) (D

Notes Receivable (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sale of notes receivable		$ 19
EnerBank notes receivable held for sale		31	$ 39
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sale of notes receivable	$ 19
Unearned income		83	84
Delinquent loans		12	11
Loans modified as troubled debt restructurings		1	1
Receivables Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
EnerBank notes receivable held for sale		31	39
Unearned income		$ 6	$ 8

Notes Receivable (Schedule Of C

Notes Receivable (Schedule Of Current And Non-Current Notes Receivable) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 197	$ 180
EnerBank notes receivable held for sale	31	39
Total notes receivable	1,382	1,326
Consumers Energy Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	30	29
Total notes receivable	46	45
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Noncurrent notes receivable	1,134	1,088
Receivables, Net Of Allowance For Loan Losses [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	167	151
Receivables Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
EnerBank notes receivable held for sale	31	39
Michigan Tax Settlement [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	30	29
Noncurrent notes receivable	20	19
Michigan Tax Settlement [Member] | Consumers Energy Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	30	29
Noncurrent notes receivable	$ 16	$ 16

Retirement Benefits (Schedule O

Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 12	$ 10	$ 34	$ 31
Interest cost	23	21	67	64
Expected return on plan assets	(39)	(36)	(115)	(110)
Amortization of Net loss	20	17	60	52
Amortization of Prior service cost (credit)	1	1	3	3
Net periodic cost (credit)	17	13	49	40
DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	11	11	33	31
Interest cost	22	20	65	62
Expected return on plan assets	(38)	(35)	(112)	(107)
Amortization of Net loss	19	16	58	50
Amortization of Prior service cost (credit)	1	1	3	3
Net periodic cost (credit)	15	13	47	39
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	5	15	14
Interest cost	13	12	39	35
Expected return on plan assets	(22)	(22)	(67)	(65)
Amortization of Net loss	7	5	23	16
Amortization of Prior service cost (credit)	(8)	(10)	(26)	(31)
Net periodic cost (credit)	(5)	(10)	(16)	(31)
OPEB Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	4	14	13
Interest cost	12	12	38	34
Expected return on plan assets	(21)	(20)	(63)	(60)
Amortization of Net loss	8	5	24	16
Amortization of Prior service cost (credit)	(8)	(10)	(25)	(30)
Net periodic cost (credit)	$ (4)	$ (9)	$ (12)	$ (27)

Income Taxes (Schedule Of Effec

Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016
Income Taxes [Line Items]
U.S. federal income tax rate		35.00%	35.00%
State and local income taxes, net of federal effect	[1]	2.30%	4.20%
Accelerated flow-through of regulatory tax benefits	[2]	(4.30%)	(4.70%)
Employee share-based awards		(0.90%)	(0.80%)
Other, net		(2.00%)	(1.40%)
Effective tax rate		30.10%	32.30%
Income tax benefit		$ 15
Income tax benefit, percent		(2.30%)
Consumers Energy Company [Member]
Income Taxes [Line Items]
U.S. federal income tax rate		35.00%	35.00%
State and local income taxes, net of federal effect	[1]	2.30%	4.60%
Accelerated flow-through of regulatory tax benefits	[2]	(3.90%)	(4.00%)
Employee share-based awards		(0.80%)	(0.70%)
Other, net		(2.30%)	(1.20%)
Effective tax rate		30.30%	33.70%
Income tax benefit		$ 16
Income tax benefit, percent		(2.20%)
Reduction of income tax expense		$ 28	$ 30
[1]	In September 2017, CMS Energy completed the evaluation of its methodology for the state apportionment of Consumers' electricity sales to MISO, taking into account recent state tax law developments in the electric utility sector. As a result, CMS Energy intends to amend state income tax filings for 2013 through 2016 to seek a refund of taxes previously paid. To recognize the anticipated refund and the impact of the expected lower effective tax rate on their deferred state tax liabilities, CMS Energy recorded a $15 million income tax benefit and Consumers recorded a $16 million income tax benefit in September 2017. Both amounts are net of reserves for uncertain tax positions. For the nine months ended September 30, 2017, the impact of the benefit was a 2.3 percentage point reduction to CMS Energy's effective tax rate and a 2.2 percentage point reduction to Consumers' effective tax rate.
[2]	Since 2014, Consumers has followed a regulatory treatment ordered by the MPSC that accelerates the return of certain income tax benefits to customers. This change, which also accelerates Consumers' recognition of the income tax benefits, reduced Consumers' income tax expense by $28 million for the nine months ended September 30, 2017 and by $30 million for the nine months ended September 30, 2016.

Earnings Per Share - CMS Ener48

Earnings Per Share - CMS Energy (Basic And Diluted EPS Computations) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share - CMS Energy [Abstract]
Net Income	$ 172	$ 186	$ 464	$ 475
Less income attributable to noncontrolling interest			1	1
Net Income Available to Common Stockholders	$ 172	$ 186	$ 463	$ 474
Weighted average shares - basic	280.8	278.2	279.8	277.7
Add dilutive nonvested stock awards	0.8	1	0.8	1.1
Weighted average shares - diluted	281.6	279.2	280.6	278.8
Basic	$ 0.61	$ 0.67	$ 1.65	$ 1.71
Diluted	$ 0.61	$ 0.67	$ 1.65	$ 1.70

Cash And Cash Equivalents (Sche

Cash And Cash Equivalents (Schedule Of Cash And Cash Equivalents, Including Restricted Amounts) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Cash and cash equivalents	$ 142	$ 235
Restricted cash and cash equivalents	27	19
Other non-current assets	4	3
Cash and cash equivalents, including restricted amounts	173	257	$ 368	$ 288
Consumers Energy Company [Member]
Cash and cash equivalents	55	131
Restricted cash and cash equivalents	27	19
Other non-current assets	3	2
Cash and cash equivalents, including restricted amounts	$ 85	$ 152	$ 50	$ 71

Cash And Cash Equivalents (Sc50

Cash And Cash Equivalents (Schedule Of Restricted Cash Balances) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities	$ (1,354)	$ (1,398)
Cash and cash equivalents, including restricted amounts, end of period	173	368	$ 257	$ 288
Consumers Energy Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities	(1,278)	(1,301)
Cash and cash equivalents, including restricted amounts, end of period	$ 85	50	$ 152	$ 71
New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities		7
Cash and cash equivalents, including restricted amounts, end of period		29
New Accounting Pronouncement, Early Adoption, Effect [Member] | Consumers Energy Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities		8
Cash and cash equivalents, including restricted amounts, end of period		$ 29

Reportable Segments (Details)

Reportable Segments (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operating Revenue		$ 1,527	$ 1,587	$ 4,805	$ 4,759
Net Income Attributable to CMS Energy		172	186	463	474
Plant, property, and equipment, gross		21,966		21,966		$ 21,010
Total Assets		22,120		22,120		21,622
Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue		1,437	1,498	4,536	4,514
Net income available to common stockholder		181	195	495	498
Plant, property, and equipment, gross		21,784		21,784		20,838
Total Assets		20,380		20,380		19,946
Electric Utility [Member]
Segment Reporting Information [Line Items]
Operating Revenue		1,247	1,313	3,360	3,348
Net Income Attributable to CMS Energy		176	191	394	395
Plant, property, and equipment, gross	[1]	15,056		15,056		14,540
Total Assets	[1]	13,639		13,639		13,429
Electric Utility [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue		1,247	1,313	3,360	3,348
Net income available to common stockholder		176	191	394	395
Plant, property, and equipment, gross	[1]	15,056		15,056		14,540
Total Assets	[1]	13,640		13,640		13,430
Gas Utility [Member]
Segment Reporting Information [Line Items]
Operating Revenue		190	185	1,176	1,166
Net Income Attributable to CMS Energy		5	3	101	102
Plant, property, and equipment, gross	[1]	6,713		6,713		6,283
Total Assets	[1]	6,701		6,701		6,446
Gas Utility [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue		190	185	1,176	1,166
Net income available to common stockholder		5	3	101	102
Plant, property, and equipment, gross	[1]	6,713		6,713		6,283
Total Assets	[1]	6,701		6,701		6,446
Enterprises [Member]
Segment Reporting Information [Line Items]
Operating Revenue		58	59	172	156
Net Income Attributable to CMS Energy		8	8	27	17
Plant, property, and equipment, gross		164		164		157
Total Assets		280		280		269
Other reconciling items [Member]
Segment Reporting Information [Line Items]
Operating Revenue		32	30	97	89
Net Income Attributable to CMS Energy		(17)	(16)	(59)	(40)
Plant, property, and equipment, gross		33		33		30
Total Assets		1,500		1,500		1,478
Other reconciling items [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Net income available to common stockholder			$ 1		$ 1
Plant, property, and equipment, gross		15		15		15
Total Assets		$ 39		$ 39		$ 70
[1]	Amounts include a portion of Consumers' other common assets attributable to both the electric and gas utility businesses.