Consumers Energy (CMS-PB) 10-K 7 Feb 17 2016 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Jan. 10, 2017	Jun. 30, 2016
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2,016
Trading Symbol	cms
Entity Registrant Name	CMS Energy Corporation
Entity Central Index Key	811,156
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 12,721
CMS Energy [Member]
Entity Common Stock, Shares Outstanding		280,014,896
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		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Revenue		$ 6,399	$ 6,456	$ 7,179
Operating Expenses
Fuel for electric generation		499	593	673
Purchased and interchange power		1,508	1,406	1,602
Purchased power - related parties		86	83	90
Cost of gas sold		710	961	1,493
Maintenance and other operating expenses		1,207	1,238	1,232
Depreciation and amortization		811	750	685
General taxes		281	262	252
Total operating expenses		5,102	5,293	6,027
Operating Income		1,297	1,163	1,152
Other Income (Expense)
Interest income		6	12	5
Allowance for equity funds used during construction		12	10	8
Income from equity method investees	[1]	13	14	15
Other income		8	10	11
Other expense		(75)	(17)	(55)
Total other income		(36)	29	(16)
Interest Charges
Interest on long-term debt		411	386	393
Other interest expense		29	14	17
Allowance for borrowed funds used during construction		(5)	(4)	(3)
Total interest charges		435	396	407
Income Before Income Taxes		826	796	729
Income Tax Expense		273	271	250
Net Income		553	525	479
Income Attributable to Noncontrolling Interests		2	2	2
Net Income Available to Common Stockholders		$ 551	$ 523	$ 477
Basic Earnings Per Average Common Share		$ 1.99	$ 1.90	$ 1.76
Diluted Earnings Per Average Common Share		$ 1.98	$ 1.89	$ 1.74
Consumers Energy Company [Member]
Operating Revenue		$ 6,064	$ 6,165	$ 6,800
Operating Expenses
Fuel for electric generation		393	497	567
Purchased and interchange power		1,486	1,376	1,564
Purchased power - related parties		88	83	89
Cost of gas sold		693	939	1,375
Maintenance and other operating expenses		1,090	1,149	1,146
Depreciation and amortization		803	744	678
General taxes		277	255	246
Total operating expenses		4,830	5,043	5,665
Operating Income		1,234	1,122	1,135
Other Income (Expense)
Interest income		4	11	4
Interest and dividend income - related parties		1	1	1
Allowance for equity funds used during construction		12	10	8
Other income		8	19	10
Other expense		(55)	(17)	(35)
Total other income		(30)	24	(12)
Interest Charges
Interest on long-term debt		261	252	243
Other interest expense		12	2	10
Allowance for borrowed funds used during construction		(5)	(4)	(3)
Total interest charges		268	250	250
Income Before Income Taxes		936	896	873
Income Tax Expense		320	302	306
Net Income		616	594	567
Preferred Stock Dividends		2	2	2
Net Income Available to Common Stockholders		$ 614	$ 592	$ 565
[1]	Consumers had no significant equity method investments.

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income	$ 553	$ 525	$ 479
Retirement Benefits Liability
Net gain (loss) arising during the period, net of tax	(8)	1	(29)
Amortization of net actuarial loss, net of tax	2	5	3
Amortization of prior service credit, net of tax	(1)	(1)	(1)
Investments
Unrealized gain (loss) on investments, net of tax	1	(3)	(1)
Other-than-temporary impairment included in net income, net of tax	3
Derivative Instruments
Reclassification adjustments included in net income, net of tax			1
Other Comprehensive Income (Loss)	(3)	2	(27)
Comprehensive Income	550	527	452
Comprehensive Income Attributable to Noncontrolling Interest	2	2	2
Comprehensive Income Attributable to CMS Energy	548	525	450
Consumers Energy Company [Member]
Net income	616	594	567
Retirement Benefits Liability
Net gain (loss) arising during the period, net of tax	(3)	3	(11)
Amortization of net actuarial loss, net of tax	1	4	2
Investments
Unrealized gain (loss) on investments, net of tax	3	(1)	4
Reclassification adjustments included in net income, net of tax		(5)
Other-than-temporary impairment included in net income, net of tax	2
Derivative Instruments
Other Comprehensive Income (Loss)	3	1	(5)
Comprehensive Income Attributable to CMS Energy	$ 619	$ 595	$ 562

Consolidated Statements Of Com4

Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net gain (loss) arising during the period, tax	$ (5)		$ (18)
Amortization of net actuarial loss, tax		$ 4	1
Amortization of prior service credit, tax
Unrealized gain (loss) on investments, tax expense (tax benefit)		(1)	(1)
Other-than-temporary impairment, tax	2
Reclassification adjustments included in net income (loss), tax
Consumers Energy Company [Member]
Net gain (loss) arising during the period, tax	(1)	2	(7)
Amortization of net actuarial loss, tax		2	1
Unrealized gain (loss) on investments, tax expense (tax benefit)	2	(1)	$ 2
Reclassification adjustments included in net income, tax		$ (3)
Other-than-temporary impairment, tax	$ 2

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows from Operating Activities
Net income	$ 553	$ 525	$ 479
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	811	750	685
Deferred income taxes and investment tax credit	264	247	227
Bad debt expense	50	58	80
Other non-cash operating activities and reconciling adjustments	52	100	58
Postretirement benefits contributions	(108)	(262)	(32)
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	(155)	120	(31)
Decrease (increase) in inventories	146	147	(36)
Increase (decrease) in accounts payable and accrued refunds	59	(26)	50
Other current and non-current assets and liabilities	(43)	(19)	1
Net cash provided by operating activities	1,629	1,640	1,481
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,672)	(1,564)	(1,577)
Jackson plant acquisition		(154)
Increase in EnerBank notes receivable	(136)	(279)	(255)
Proceeds from the sale of EnerBank notes receivable		48
Cost to retire property and other investing activities	(107)	(115)	(66)
Net cash used in investing activities	(1,915)	(2,064)	(1,898)
Cash Flows from Financing Activities
Proceeds from issuance of debt	1,049	599	1,428
Proceeds from EnerBank certificates of deposit, net	100	214	233
Issuance of common stock	72	43	43
Retirement of long-term debt	(728)	(224)	(750)
Debt prepayment costs	(18)		(36)
Payment of dividends on common and preferred stock	(347)	(322)	(295)
Increase (decrease) in notes payable	149	189	(110)
Payment of capital lease obligations and other financing costs	(22)	(36)	(51)
Net cash provided by (used in) financing activities	255	463	462
Net Increase (Decrease in Cash and Cash Equivalents, Including Restricted Amounts	(31)	39	45
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	288	249	204
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	257	288	249
Cash transactions
Interest paid (net of amounts capitalized)	427	386	380
Income taxes paid (refunds received), net	32	10	22
Non-cash transactions
Capital expenditures not paid	138	201	201
Note receivable recorded for future refund of use taxes paid and capitalized	29
Other assets placed under capital lease	13	17	7
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net income	616	594	567
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	803	744	678
Deferred income taxes and investment tax credit	289	204	263
Bad debt expense	31	50	72
Other non-cash operating activities and reconciling adjustments	25	98	34
Postretirement benefits contributions	(98)	(243)	(29)
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	(138)	104	(16)
Decrease (increase) in inventories	145	144	(36)
Increase (decrease) in accounts payable and accrued refunds	57	(22)	47
Other current and non-current assets and liabilities	(49)	121	(226)
Net cash provided by operating activities	1,681	1,794	1,354
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,656)	(1,537)	(1,573)
Jackson plant acquisition		(154)
Cost to retire property and other investing activities	(112)	(110)	(70)
Net cash used in investing activities	(1,768)	(1,801)	(1,643)
Cash Flows from Financing Activities
Proceeds from issuance of debt	446	250	878
Retirement of long-term debt	(198)	(124)	(220)
Debt prepayment costs			(16)
Payment of dividends on common and preferred stock	(501)	(476)	(459)
Stockholder contribution	275	150	495
Increase (decrease) in notes payable	149	189	(110)
Return of stockholder contribution			(178)
Payment of capital lease obligations and other financing costs	(3)	(23)	(38)
Net cash provided by (used in) financing activities	168	(34)	352
Net Increase (Decrease in Cash and Cash Equivalents, Including Restricted Amounts	81	(41)	63
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	71	112	49
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	152	71	112
Cash transactions
Interest paid (net of amounts capitalized)	256	245	233
Income taxes paid (refunds received), net	50	(84)	266
Non-cash transactions
Capital expenditures not paid	127	182	201
Note receivable recorded for future refund of use taxes paid and capitalized	29
Other assets placed under capital lease	$ 13	$ 17	$ 7

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents		$ 235	$ 266
Restricted cash and cash equivalents		19	19
Accounts receivable and accrued revenue, less allowances		821	774
Notes receivable, less allowances		180	128
Notes receivable held for sale		39	16
Accounts receivable - related parties		12	11
Inventories at average cost
Gas in underground storage		446	568
Materials and supplies		119	126
Generating plant fuel stock		61	84
Deferred property taxes		250	235
Regulatory assets		17	16
Prepayments and other current assets		81	77
Total current assets		2,280	2,320
Plant, Property, and Equipment
Plant, property, and equipment, gross		21,010	18,943
Less accumulated depreciation and amortization		6,056	5,747
Plant, property, and equipment, net		14,954	13,196
Construction work in progress		761	1,509
Total plant, property, and equipment	[1]	15,715	14,705
Other Non-current Assets
Regulatory assets		2,091	1,840
Accounts and notes receivable		1,118	1,027
Investments	[2]	65	64
Other		353	343
Total other non-current assets		3,627	3,274
Total Assets		21,622	20,299
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation		886	706
Notes payable		398	249
Accounts payable		598	633
Accounts payable - related parties		12	9
Accrued rate refunds		21	26
Accrued interest		98	106
Accrued taxes		348	349
Regulatory liabilities		95	82
Other current liabilities		199	142
Total current liabilities		2,655	2,302
Non-current Liabilities
Long-term debt		8,640	8,400
Non-current portion of capital leases and financing obligation		110	118
Regulatory liabilities		2,041	2,088
Postretirement benefits		789	591
Asset retirement obligations		447	439
Deferred investment tax credit		73	56
Deferred income taxes		2,287	2,017
Other non-current liabilities		290	313
Total non-current liabilities		14,677	14,022
Commitments and Contingencies (Notes 3, 4, and 5)
Common stockholder's equity
Common stock		3	3
Other paid-in capital		4,916	4,837
Accumulated other comprehensive loss		(50)	(47)
Retained earnings (Accumulated deficit)		(616)	(855)
Total common stockholders' equity		4,253	3,938
Noncontrolling interests		37	37
Total equity		4,290	3,975
Total Liabilities and Equity		21,622	20,299
Consumers Energy Company [Member]
Current Assets
Cash and cash equivalents		131	50
Restricted cash and cash equivalents		19	19
Accounts receivable and accrued revenue, less allowances		800	758
Notes receivable, less allowances		29
Accounts receivable - related parties		9	17
Inventories at average cost
Gas in underground storage		446	568
Materials and supplies		114	120
Generating plant fuel stock		57	80
Deferred property taxes		250	235
Regulatory assets		17	16
Prepayments and other current assets		70	66
Total current assets		1,942	1,929
Plant, Property, and Equipment
Plant, property, and equipment, gross		20,838	18,797
Less accumulated depreciation and amortization		5,994	5,676
Plant, property, and equipment, net		14,844	13,121
Construction work in progress		759	1,467
Total plant, property, and equipment	[1]	15,603	14,588
Other Non-current Assets
Regulatory assets		2,091	1,840
Accounts and notes receivable		27	10
Investments		33	29
Other		250	239
Total other non-current assets		2,401	2,118
Total Assets		19,946	18,635
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation		397	220
Notes payable		398	249
Accounts payable		580	613
Accounts payable - related parties		18	15
Accrued rate refunds		21	26
Accrued interest		67	65
Accrued taxes		354	352
Regulatory liabilities		95	82
Other current liabilities		164	109
Total current liabilities		2,094	1,731
Non-current Liabilities
Long-term debt		5,253	5,183
Non-current portion of capital leases and financing obligation		110	118
Regulatory liabilities		2,041	2,088
Postretirement benefits		730	529
Asset retirement obligations		446	438
Deferred investment tax credit		73	56
Deferred income taxes		3,042	2,710
Other non-current liabilities		218	236
Total non-current liabilities		11,913	11,358
Commitments and Contingencies (Notes 3, 4, and 5)
Common stockholder's equity
Common stock		841	841
Other paid-in capital		3,999	3,724
Accumulated other comprehensive loss		(3)	(6)
Retained earnings (Accumulated deficit)		1,065	950
Total common stockholders' equity		5,902	5,509
Preferred stock		37	37
Total equity		5,939	5,546
Total Liabilities and Equity		$ 19,946	$ 18,635
[1]	For the year ended December 31, 2016, Consumers' plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 2015, Consumers' plant additions were $1.4 billion and plant retirements were $187 million.
[2]	Consumers had no significant equity method investments.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Allowances for doubtful accounts receivable	$ 24	$ 28
Allowances for doubtful notes receivable	$ 16	$ 9
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares outstanding	279,200,000	277,200,000
Consumers Energy Company [Member]
Allowances for doubtful accounts receivable	$ 24	$ 28
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 Income (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 Income (Loss) [Member]	Retirement Benefits Liability [Member]	Investments [Member]	Derivative Instruments [Member]	Retained Earnings (Accumulated Deficit) [Member]	Noncontrolling Interest [Member]	Total
Total Equity, beginning at Dec. 31, 2013	$ 841	$ 3,257	$ (2)	$ (17)	$ 15	$ 724	$ 37	$ 4,857	$ 3	$ 4,715	$ (22)	$ (21)		$ (1)	$ (1,242)	$ 37	$ 3,491
Beginning of period, shares at Dec. 31, 2013									266,137,000
Common stock issued										59
Number of Shares Issued									9,371,000
Common stock repurchased										(7)
Common stock repurchased, shares									(271,000)
Common stock reissued
Common stock reissued, shares
Conversion option on convertible debt										7
Common stock reacquired, value
Common stock reacquired, shares									(53,000)
Stockholder contribution		495
Return of stockholder contribution		(178)
Net gain arising during the period				(11)				(11)				(29)					(29)
Amortization of net actuarial loss, net of tax				2				2				3					3
Amortization of prior service credit												(1)					(1)
Unrealized gain (loss) on investments, net of tax					4			4					(1)				(1)
Reclassification adjustments included in net income
Reclassification adjustments included in net income														1			(1)
Net income attributable to CMS Energy															477		477
Net income						567		567									479
Dividends declared on common stock						(457)									(293)
Dividends declared on preferred stock						(2)
Income Attributable to Noncontrolling Interests																2	2
Distributions, and other changes in noncontrolling interests																(2)
End of period, shares at Dec. 31, 2014									275,184,000
Total Equity, end at Dec. 31, 2014	841	3,574	(7)	(26)	19	832	37	5,277	$ 3	4,774	(49)	(48)	(1)		(1,058)	37	3,707
Common stock issued										65							$ 30
Number of Shares Issued									2,062,000								888,610
Common stock repurchased										(12)
Common stock repurchased, shares									(306,000)
Common stock reissued										10
Common stock reissued, shares									288,000
Conversion option on convertible debt
Common stock reacquired, value
Common stock reacquired, shares									(65,000)
Stockholder contribution		150
Return of stockholder contribution
Net gain arising during the period				3				3				1					$ 1
Amortization of net actuarial loss, net of tax				4				4				5					5
Amortization of prior service credit												(1)					(1)
Unrealized gain (loss) on investments, net of tax					(1)			(1)					(3)				(3)
Reclassification adjustments included in net income					(5)			5
Reclassification adjustments included in net income
Net income attributable to CMS Energy															523		523
Net income						594		$ 594									525
Dividends declared on common stock						(474)									(320)
Dividends declared on preferred stock						(2)
Income Attributable to Noncontrolling Interests																2	$ 2
Distributions, and other changes in noncontrolling interests																(2)
End of period, shares at Dec. 31, 2015								84,100,000	277,163,000								277,200,000
Total Equity, end at Dec. 31, 2015	841	3,724	(6)	(19)	13	950	37	$ 5,546	$ 3	4,837	(47)	(43)	(4)		(855)	37	$ 3,975
Total Equity, beginning at Dec. 31, 2014	841	3,574	(7)	(26)	19	832	37	$ 5,277	$ 3	4,774	(49)	(48)	(1)		(1,058)	37	3,707
Beginning of period, shares at Dec. 31, 2014									275,184,000
Common stock issued																	$ 90
Number of Shares Issued																	2,337,781
End of period, shares at Dec. 31, 2016								84,100,000	279,206,000								279,200,000
Total Equity, end at Dec. 31, 2016	841	3,999	(3)	(21)	18	1,065	37	$ 5,939	$ 3	4,916	(50)	(50)			(616)	37	$ 4,290
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
Beginning of period, shares at Dec. 31, 2015								84,100,000	277,163,000								277,200,000
Common stock issued										90							$ 60
Number of Shares Issued									2,580,000								1,449,171
Common stock repurchased										(11)
Common stock repurchased, shares									(292,000)
Common stock reissued
Common stock reissued, shares
Conversion option on convertible debt
Common stock reacquired, value
Common stock reacquired, shares									(245,000)
Stockholder contribution		275
Return of stockholder contribution
Net gain arising during the period				(3)				$ (3)				(8)					$ (8)
Amortization of net actuarial loss, net of tax				1				1				2					2
Amortization of prior service credit												(1)					(1)
Unrealized gain (loss) on investments, net of tax					3			3					1				1
Reclassification adjustments included in net income
Other-than-temporary impairment included in net income					2			2					3				3
Reclassification adjustments included in net income
Net income attributable to CMS Energy															551		551
Net income						616		$ 616									553
Dividends declared on common stock						(499)									(345)
Dividends declared on preferred stock						(2)
Income Attributable to Noncontrolling Interests																2	$ 2
Distributions, and other changes in noncontrolling interests																(2)
End of period, shares at Dec. 31, 2016								84,100,000	279,206,000								279,200,000
Total Equity, end at Dec. 31, 2016	$ 841	$ 3,999	$ (3)	$ (21)	$ 18	$ 1,065	$ 37	$ 5,939	$ 3	$ 4,916	$ (50)	$ (50)			(616)	$ 37	$ 4,290
Cumulative effect of change in accounting principle															$ 33		$ 33

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Significant Accounting Policies	1: S ignificant A ccounting P olicies Principles of Consolidation: CMS Energy and Consumers prepare their consolidated financial statements in conformity with GAAP. CMS Energy’s co nsolidated financial statements comprise CMS Energy, Consumers, CMS Enterprises, and all other entities in which CMS Energy has a controlling financial interest or is the primary beneficiary. Consumers’ consolidated financial statements comprise Consumers and all other entities in which it has a controlling financial interest or is the primary beneficiary. CMS Energy uses the equity method of accounting for investments in companies and partnerships that are not consolidated, where they have significant influence over operations and financial policies but are not the primary beneficiary. CMS Energy and Consumers eliminate intercompany transactions and balances. Use of Estimates : CMS Energy and Consumers are required to make estimates using assumptions that may affect reported amounts and disclosures. Actual results could differ from those estimates. Revenue Recognition Policy: CMS Energy and Consumers recognize revenue from deliveries of electricity and natural gas, and from the transportation, processing, and storage of natural gas, when services are provided. CMS Energy and Consumers record unbilled revenue for the estimated amount of energy delivered to customers but not yet billed. CMS Energy and Consumers record sales tax net and exclude it from revenue. CMS Energy recognizes revenue on sales of marketed electricity, natural gas, and other energy products at delivery. Alternative-Revenue Program: The energy optimization incentive mechanism provides a financial incentive if the energy savings of Consumers’ customers exceed annual targets established by the MPSC. The maximum incentive that Consumers may earn under this mechanism is 15 percent of the amount it spends on energy optimization programs, which is limited to two percent of Consumers’ retail revenue. Consumers accounts for this program as an alternative-revenue program that meets the criteria for recognizing revenue related to the incentive as soon as energy savings exceed the annual targets established by the MPSC. The 2016 Energy Law, which will become effective in April 2017, expands existing incentives for energy efficiency programs. Self-Implemented Rates: Unless prohibited by the MPSC upon a showing of good cause, Consumers is allowed to self-implement new energy rates six months after a new rate case filing if the MPSC has not issued an order in the case. The MPSC then has another six months to issue a final order. If the MPSC does not issue a final order within that period, the filed rates are considered approved. If the MPSC issues a final order within that period, the rates that Consumers self-implemented may be subject to refund, with interest. Consumers recognizes revenue associated with self-implemented rates. If Consumers considers it probable that it will be required to refund a portion of its self-implemented rates, then Consumers records a provision for revenue subject to refund. The 2016 Energy Law, which will become effective in April 2017, eliminates utilities’ self-implementation of rates under general rate cases, but provides for more timely processing of general rate cases. EnerBank: EnerBank provides four types of unsecured consumer installment loans: same-as-cash, zero interest, reduced interest, and traditional. Under EnerBank’s same-as-cash programs, authorized contractors pay EnerBank a fee to provide a borrower with the option to pay off the loan interest-free during the same-as-cash period. EnerBank recognizes the fee on a straight-line basis over the same-as-cash period, which typically ranges from three to 24 months. If a borrower does not exercise its option to pay off its loan interest-free during the same-as-cash period, EnerBank charges the borrower accrued interest at the loan’s contractual rate on the outstanding balance from the origination date. Under the zero interest and reduced interest programs, authorized contractors pay EnerBank a fee to provide a borrower with no interest or reduced rates of interest for the entire term of the loan. EnerBank recognizes the fee using the interest method over the term of the loan, which ranges from one to 12 years. Unearned income associated with the fees is recorded as a reduction to notes receivable on CMS Energy’s consolidated balance sheets. EnerBank recognizes interest income using the interest method and amortizes loan origination fees, net of certain direct origination costs, over the loan term. EnerBank ceases recognizing interest income when a loan loss is confirmed or when a loan becomes 120 days past due, at which time the loan principal is charged against the allowance for loan losses. At that time, EnerBank recognizes any interest accrued but not received for such loan losses as a reversal of interest income. The loan fees and interest income earned by EnerBank are reported as operating revenue on CMS Energy’s consolidated statements of income. Accounts Receivable: Accounts receivable comprise trade receivables and unbilled receivables. CMS Energy and Consumers record their accounts receivable at cost, which approximates fair value. CMS Energy and Consumers establish an allowance for uncollectible accounts based on historical losses, management’s assessment of existing economic conditions, customer trends, and other factors. CMS Energy and Consumers assess late payment fees on trade receivables based on contractual past-due terms established with customers. CMS Energy and Consumers charge off accounts deemed uncollectible to operating expense. Contingencies: CMS Energy and Consumers record estimated liabilities for contingencies on their consolidated financial statements when it is probable that a liability has been incurred and when the amount of loss can be reasonably estimated. For environmental remediation projects in which the timing of estimated expenditures is considered reliably determinable, CMS Energy and Consumers record the liability at its net present value, using a discount rate equal to the interest rate on monetary assets that are essentially risk-free and have maturities comparable to that of the environmental liability. CMS Energy and Consumers expense legal fees as incurred; fees incurred but not yet billed are accrued based on estimates of work performed. Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs: Upon the issuance of long-term debt, CMS Energy and Consumers defer issuance costs, discounts, and premiums and amortize those amounts over the terms of the associated debt. Debt issuance costs are presented as a direct deduction from the carrying amount of long-term debt on the balance sheet. Upon the refinancing of long-term debt, Consumers, as a regulated entity, defers any remaining unamortized issuance costs, discounts, and premiums associated with the refinanced debt and amortizes those amounts over the term of the newly issued debt. For the non ‑regulated portions of CMS Energy’s business, any remaining unamortized issuance costs, discounts, and premiums associated with extinguished debt are charged to earnings. Derivative Instruments: In order to support ongoing operations, CMS Energy and Consumers enter into contracts for the future purchase and sale of various commodities, such as electricity, natural gas, and coal. These forward contracts are generally long-term in nature and result in physical delivery of the commodity at a contracted price. Most of these contracts are not subject to derivative accounting for one or more of the following reasons: · they do not have a notional amount (that is, a number of units specified in a derivative instrument, such as MWh of electricity or bcf of natural gas) · they qualify for the normal purchases and sales exception · there is not an active market for the commodity Consumers’ coal purchase contracts are not derivatives because there is not an active market for the coal it purchases. If an active market for coal develops in the future, some of these contracts may qualify as derivatives. Since Consumers is subject to regulatory accounting, the resulting fair value gains and losses would be deferred as regulatory assets or liabilities an d would not affect net income. Consumers also 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. Consumers accounts for FTRs as derivatives. All changes in fair value associated with FTRs are deferred as regulatory assets and liabilities until the instruments are settled. CMS Energy and Consumers record derivative contracts that do not qualify for the normal purchases and sales exception at fair value on their consolidated balance sheets. Each reporting period, the resulting asset or liability is adjusted to reflect any change in the fair value of the contract. Since none of CMS Energy’s or Consumers’ derivatives has been designated as an accounting hedge, all changes in fair value are either reported in earnings or deferred as regulatory assets or liabilities. For details regarding CMS Energy’s and Consumers’ derivative instruments recorded at fair value, see Note 6, Fair Value Measurements. Earnings Per Share: CMS Energy calculates basic and diluted EPS using the weighted-average number of shares of common stock and dilutive potential common stock outstanding during the period. Potential common stock, for purposes of determining diluted EPS, includes the effects of nonvested stock awards and contingently convertible securities. CMS Energy computes the effect on potential common stock using the treasury stock method or the if ‑converted method, as applicable. Diluted EPS excludes the impact of antidilutive securities, which are those securities resulting in an increase in EPS or a decrease in loss per share. For EPS computations, see Note 15, Earnings Per Share—CMS Energy. Financial Instruments: CMS Energy and Consumers record debt and equity securities classified as available for sale at fair value as determined from quoted market prices or other observable, market-based inputs. Unrealized gains and losses resulting from changes in fair value of these securities are determined on a specific-identification basis. CMS Energy and Consumers report unrealized gains and losses on these securities, net of tax, in equity as part of AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. For additional details regarding financial instruments, see Note 7, Financial Instruments. Impairment of Long-Lived Assets and Equity Method Investments: CMS Energy and Consumers perform tests of impairment if certain triggering events occur or if there has been a decline in value that may be other than temporary. CMS Energy and Consumers evaluate long-lived assets held in use for impairment by calculating the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. If the undiscounted future cash flows are less than the carrying amount, CMS Energy and Consumers recognize an impairment loss equal to the amount by which the carrying amount exceeds the fair value. CMS Energy and Consumers estimate the fair value of the asset using quoted market prices, market prices of similar assets, or discounted future cash flow analyses. CMS Energy also assesses equity method investments for impairment whenever there has been a decline in value that is other than temporary. This assessment requires CMS Energy to determine the fair value of the equity method investment. CMS Energy determines fair value using valuation methodologies, including discounted cash flows, and assesses the ability of the investee to sustain an earnings capacity that justifies the carrying amount of the investment. CMS Energy records an impairment if the fair value is less than the carrying amount and the decline in value is considered to be other than temporary. Inventory: CMS Energy and Consumers use the weighted-average cost method for valuing working gas, recoverable base gas in underground storage facilities, and materials and supplies inventory. CMS Energy and Consumers also use this method for valuing coal inventory, and they classify these amounts as generating plant fuel stock on their consolidated balance sheets. CMS Energy and Consumers account for RECs and emission allowances as inventory and use the weighted-average cost method to remove amounts from inventory. RECs and emission allowances are used to satisfy compliance obligations related to the generation of power. CMS Energy and Consumers classify these amounts within other assets on their consolidated balance sheets. CMS Energy and Consumers evaluate inventory for impairment as required to ensure that its carrying value does not exceed the lower of cost or net realizable value. MISO Transactions: MISO requires the submission of hourly day-ahead and real-time bids and offers for energy at locations across the MISO region. CMS Energy and Consumers account for MISO transactions on a net hourly basis in each of the real-time and day-ahead markets, netted across all MISO energy market locations. CMS Energy and Consumers record net hourly purchases in purchased and interchange power and net hourly sales in operating revenue on their consolidated statements of income. They record net billing adjustments upon receipt of settlement statements, record accruals for future net purchases and sales adjustments based on historical experience, and reconcile accruals to actual expenses and sales upon receipt of settlement statements. Property Taxes: Property taxes are based on the taxable value of Consumers’ real and personal property assessed by local taxing authorities. Consumers records property tax expense over the fiscal year of the taxing authority for which the taxes are levied based on Consumers’ budgeted customer sales. The deferred property tax balance represents the amount of Consumers’ accrued property tax that will be recognized over future governmental fiscal periods. Renewable Energy Grant: In 2013, Consumers received a renewable energy cash grant for Lake Winds ® Energy Park under Section 1603 of the American Recovery and Reinvestment Tax Act of 2009. Upon receipt of the grant, Consumers recorded a regulatory liability, which Consumers is amortizing over the life of Lake Winds ® Energy Park. Consumers presents the amortization as a reduction to maintenance and other operating expenses on its consolidated statements of income. Consumers recorded the deferred income taxes related to the grant as a reduction of the book basis of Lake Winds ® Energy Park. Other: For additional accounting policies, see : · Note 8, Notes Receivable · Note 9, Plant, Property, and Equipment · Note 11, Asset Retirement Obligations · Note 12, Retirement Benefits · Note 14, Income Taxes · Note 17, Cash and Cash Equivalents
Consumers Energy Company [Member]
Significant Accounting Policies	1: S ignificant A ccounting P olicies Principles of Consolidation: CMS Energy and Consumers prepare their consolidated financial statements in conformity with GAAP. CMS Energy’s co nsolidated financial statements comprise CMS Energy, Consumers, CMS Enterprises, and all other entities in which CMS Energy has a controlling financial interest or is the primary beneficiary. Consumers’ consolidated financial statements comprise Consumers and all other entities in which it has a controlling financial interest or is the primary beneficiary. CMS Energy uses the equity method of accounting for investments in companies and partnerships that are not consolidated, where they have significant influence over operations and financial policies but are not the primary beneficiary. CMS Energy and Consumers eliminate intercompany transactions and balances. Use of Estimates : CMS Energy and Consumers are required to make estimates using assumptions that may affect reported amounts and disclosures. Actual results could differ from those estimates. Revenue Recognition Policy: CMS Energy and Consumers recognize revenue from deliveries of electricity and natural gas, and from the transportation, processing, and storage of natural gas, when services are provided. CMS Energy and Consumers record unbilled revenue for the estimated amount of energy delivered to customers but not yet billed. CMS Energy and Consumers record sales tax net and exclude it from revenue. CMS Energy recognizes revenue on sales of marketed electricity, natural gas, and other energy products at delivery. Alternative-Revenue Program: The energy optimization incentive mechanism provides a financial incentive if the energy savings of Consumers’ customers exceed annual targets established by the MPSC. The maximum incentive that Consumers may earn under this mechanism is 15 percent of the amount it spends on energy optimization programs, which is limited to two percent of Consumers’ retail revenue. Consumers accounts for this program as an alternative-revenue program that meets the criteria for recognizing revenue related to the incentive as soon as energy savings exceed the annual targets established by the MPSC. The 2016 Energy Law, which will become effective in April 2017, expands existing incentives for energy efficiency programs. Self-Implemented Rates: Unless prohibited by the MPSC upon a showing of good cause, Consumers is allowed to self-implement new energy rates six months after a new rate case filing if the MPSC has not issued an order in the case. The MPSC then has another six months to issue a final order. If the MPSC does not issue a final order within that period, the filed rates are considered approved. If the MPSC issues a final order within that period, the rates that Consumers self-implemented may be subject to refund, with interest. Consumers recognizes revenue associated with self-implemented rates. If Consumers considers it probable that it will be required to refund a portion of its self-implemented rates, then Consumers records a provision for revenue subject to refund. The 2016 Energy Law, which will become effective in April 2017, eliminates utilities’ self-implementation of rates under general rate cases, but provides for more timely processing of general rate cases. EnerBank: EnerBank provides four types of unsecured consumer installment loans: same-as-cash, zero interest, reduced interest, and traditional. Under EnerBank’s same-as-cash programs, authorized contractors pay EnerBank a fee to provide a borrower with the option to pay off the loan interest-free during the same-as-cash period. EnerBank recognizes the fee on a straight-line basis over the same-as-cash period, which typically ranges from three to 24 months. If a borrower does not exercise its option to pay off its loan interest-free during the same-as-cash period, EnerBank charges the borrower accrued interest at the loan’s contractual rate on the outstanding balance from the origination date. Under the zero interest and reduced interest programs, authorized contractors pay EnerBank a fee to provide a borrower with no interest or reduced rates of interest for the entire term of the loan. EnerBank recognizes the fee using the interest method over the term of the loan, which ranges from one to 12 years. Unearned income associated with the fees is recorded as a reduction to notes receivable on CMS Energy’s consolidated balance sheets. EnerBank recognizes interest income using the interest method and amortizes loan origination fees, net of certain direct origination costs, over the loan term. EnerBank ceases recognizing interest income when a loan loss is confirmed or when a loan becomes 120 days past due, at which time the loan principal is charged against the allowance for loan losses. At that time, EnerBank recognizes any interest accrued but not received for such loan losses as a reversal of interest income. The loan fees and interest income earned by EnerBank are reported as operating revenue on CMS Energy’s consolidated statements of income. Accounts Receivable: Accounts receivable comprise trade receivables and unbilled receivables. CMS Energy and Consumers record their accounts receivable at cost, which approximates fair value. CMS Energy and Consumers establish an allowance for uncollectible accounts based on historical losses, management’s assessment of existing economic conditions, customer trends, and other factors. CMS Energy and Consumers assess late payment fees on trade receivables based on contractual past-due terms established with customers. CMS Energy and Consumers charge off accounts deemed uncollectible to operating expense. Contingencies: CMS Energy and Consumers record estimated liabilities for contingencies on their consolidated financial statements when it is probable that a liability has been incurred and when the amount of loss can be reasonably estimated. For environmental remediation projects in which the timing of estimated expenditures is considered reliably determinable, CMS Energy and Consumers record the liability at its net present value, using a discount rate equal to the interest rate on monetary assets that are essentially risk-free and have maturities comparable to that of the environmental liability. CMS Energy and Consumers expense legal fees as incurred; fees incurred but not yet billed are accrued based on estimates of work performed. Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs: Upon the issuance of long-term debt, CMS Energy and Consumers defer issuance costs, discounts, and premiums and amortize those amounts over the terms of the associated debt. Debt issuance costs are presented as a direct deduction from the carrying amount of long-term debt on the balance sheet. Upon the refinancing of long-term debt, Consumers, as a regulated entity, defers any remaining unamortized issuance costs, discounts, and premiums associated with the refinanced debt and amortizes those amounts over the term of the newly issued debt. For the non ‑regulated portions of CMS Energy’s business, any remaining unamortized issuance costs, discounts, and premiums associated with extinguished debt are charged to earnings. Derivative Instruments: In order to support ongoing operations, CMS Energy and Consumers enter into contracts for the future purchase and sale of various commodities, such as electricity, natural gas, and coal. These forward contracts are generally long-term in nature and result in physical delivery of the commodity at a contracted price. Most of these contracts are not subject to derivative accounting for one or more of the following reasons: · they do not have a notional amount (that is, a number of units specified in a derivative instrument, such as MWh of electricity or bcf of natural gas) · they qualify for the normal purchases and sales exception · there is not an active market for the commodity Consumers’ coal purchase contracts are not derivatives because there is not an active market for the coal it purchases. If an active market for coal develops in the future, some of these contracts may qualify as derivatives. Since Consumers is subject to regulatory accounting, the resulting fair value gains and losses would be deferred as regulatory assets or liabilities an d would not affect net income. Consumers also 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. Consumers accounts for FTRs as derivatives. All changes in fair value associated with FTRs are deferred as regulatory assets and liabilities until the instruments are settled. CMS Energy and Consumers record derivative contracts that do not qualify for the normal purchases and sales exception at fair value on their consolidated balance sheets. Each reporting period, the resulting asset or liability is adjusted to reflect any change in the fair value of the contract. Since none of CMS Energy’s or Consumers’ derivatives has been designated as an accounting hedge, all changes in fair value are either reported in earnings or deferred as regulatory assets or liabilities. For details regarding CMS Energy’s and Consumers’ derivative instruments recorded at fair value, see Note 6, Fair Value Measurements. Earnings Per Share: CMS Energy calculates basic and diluted EPS using the weighted-average number of shares of common stock and dilutive potential common stock outstanding during the period. Potential common stock, for purposes of determining diluted EPS, includes the effects of nonvested stock awards and contingently convertible securities. CMS Energy computes the effect on potential common stock using the treasury stock method or the if ‑converted method, as applicable. Diluted EPS excludes the impact of antidilutive securities, which are those securities resulting in an increase in EPS or a decrease in loss per share. For EPS computations, see Note 15, Earnings Per Share—CMS Energy. Financial Instruments: CMS Energy and Consumers record debt and equity securities classified as available for sale at fair value as determined from quoted market prices or other observable, market-based inputs. Unrealized gains and losses resulting from changes in fair value of these securities are determined on a specific-identification basis. CMS Energy and Consumers report unrealized gains and losses on these securities, net of tax, in equity as part of AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. For additional details regarding financial instruments, see Note 7, Financial Instruments. Impairment of Long-Lived Assets and Equity Method Investments: CMS Energy and Consumers perform tests of impairment if certain triggering events occur or if there has been a decline in value that may be other than temporary. CMS Energy and Consumers evaluate long-lived assets held in use for impairment by calculating the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. If the undiscounted future cash flows are less than the carrying amount, CMS Energy and Consumers recognize an impairment loss equal to the amount by which the carrying amount exceeds the fair value. CMS Energy and Consumers estimate the fair value of the asset using quoted market prices, market prices of similar assets, or discounted future cash flow analyses. CMS Energy also assesses equity method investments for impairment whenever there has been a decline in value that is other than temporary. This assessment requires CMS Energy to determine the fair value of the equity method investment. CMS Energy determines fair value using valuation methodologies, including discounted cash flows, and assesses the ability of the investee to sustain an earnings capacity that justifies the carrying amount of the investment. CMS Energy records an impairment if the fair value is less than the carrying amount and the decline in value is considered to be other than temporary. Inventory: CMS Energy and Consumers use the weighted-average cost method for valuing working gas, recoverable base gas in underground storage facilities, and materials and supplies inventory. CMS Energy and Consumers also use this method for valuing coal inventory, and they classify these amounts as generating plant fuel stock on their consolidated balance sheets. CMS Energy and Consumers account for RECs and emission allowances as inventory and use the weighted-average cost method to remove amounts from inventory. RECs and emission allowances are used to satisfy compliance obligations related to the generation of power. CMS Energy and Consumers classify these amounts within other assets on their consolidated balance sheets. CMS Energy and Consumers evaluate inventory for impairment as required to ensure that its carrying value does not exceed the lower of cost or net realizable value. MISO Transactions: MISO requires the submission of hourly day-ahead and real-time bids and offers for energy at locations across the MISO region. CMS Energy and Consumers account for MISO transactions on a net hourly basis in each of the real-time and day-ahead markets, netted across all MISO energy market locations. CMS Energy and Consumers record net hourly purchases in purchased and interchange power and net hourly sales in operating revenue on their consolidated statements of income. They record net billing adjustments upon receipt of settlement statements, record accruals for future net purchases and sales adjustments based on historical experience, and reconcile accruals to actual expenses and sales upon receipt of settlement statements. Property Taxes: Property taxes are based on the taxable value of Consumers’ real and personal property assessed by local taxing authorities. Consumers records property tax expense over the fiscal year of the taxing authority for which the taxes are levied based on Consumers’ budgeted customer sales. The deferred property tax balance represents the amount of Consumers’ accrued property tax that will be recognized over future governmental fiscal periods. Renewable Energy Grant: In 2013, Consumers received a renewable energy cash grant for Lake Winds ® Energy Park under Section 1603 of the American Recovery and Reinvestment Tax Act of 2009. Upon receipt of the grant, Consumers recorded a regulatory liability, which Consumers is amortizing over the life of Lake Winds ® Energy Park. Consumers presents the amortization as a reduction to maintenance and other operating expenses on its consolidated statements of income. Consumers recorded the deferred income taxes related to the grant as a reduction of the book basis of Lake Winds ® Energy Park. Other: For additional accounting policies, see : · Note 8, Notes Receivable · Note 9, Plant, Property, and Equipment · Note 11, Asset Retirement Obligations · Note 12, Retirement Benefits · Note 14, Income Taxes · Note 17, Cash and Cash Equivalents

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2016
New Accounting Standards	2: New Accounting Standards Implementation of New Accounting Standards ASU 2014 ‑12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period: This standard, which was effective on January 1, 2016 for CMS Energy and Consumers, addresses stock awards with performance targets that can be met after an employee has completed the required service period. The standard was issued to resolve diversity in practice regarding the accounting treatment for this type of award. Under the new guidance, the probability of the performance target being met should be factored into compensation expense each period. This guidance is consistent with the accounting that CMS Energy and Consumers already applied to awards of this type. Therefore, the standard had no impact on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2015 ‑02, Amendments to the Consolidation Analysis: This standard, which was effective on January 1, 2016 for CMS Energy and Consumers, provides amended guidance on whether reporting entities should consolidate certain legal entities, including limited partnerships. CMS Energy and Consumers determined that the standard did not change any of their consolidation conclusions or have any impact on their consolidated net income, cash flows, or financial position. ASU 2015 ‑03, Simplifying the Presentation of Debt Issuance Costs: This standard, which was effective on January 1, 2016 for CMS Energy and Consumers, requires that debt issuance costs be presented as a direct deduction from the carrying amount of long-term debt on the balance sheet. Previously, debt issuance costs were reported as an asset. The new guidance aligns the presentation of debt issuance costs with debt discounts and premiums. In accordance with the standard, CMS Energy included $45 million and Consumers included $25 million of unamortized debt issuance costs in long-term debt on their consolidated balance sheets at December 31, 2016. In addition, this standard requires that entities apply the new guidance retrospectively to all prior periods presented. Accordingly, CMS Energy reclassified $41 million and Consumers reclassified $23 million of unamortized debt issuance costs from other non ‑current assets to long-term debt on their consolidated balance sheets at December 31, 2015. ASU 2016 ‑09, Improvements to Employee Share-Based Payment Accounting: This standard was issued to simplify and improve the accounting for employee share-based payment awards. The required effective date of the standard for CMS Energy and Consumers is January 1, 2017, but early adoption is permitted. CMS Energy and Consumers elected to adopt the standard early as of January 1, 2016. The standard requires all excess tax benefits and deficiencies that occur upon vesting of employee stock awards to be recognized in net income. Previously, CMS Energy and Consumers did not record excess tax benefits on restricted stock awards in net income but, under this standard, CMS Energy and Consumers recorded $7 million of excess tax benefits in net income for the year ended December 31, 2016. Also, in accordance with the standard, CMS Energy recorded a $33 million cumulative adjustment to its accumulated deficit at January 1, 2016. This amount represented excess federal tax benefits that CMS Energy had not recognized in prior periods due to the use of tax loss carryforwards. The implementation of this standard had no other major impacts on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2016 ‑15, Classification of Certain Cash Receipts and Cash Payments: This standard provides guidance on how certain cash receipts and cash payments should be classified in the statement of cash flows, with the objective of reducing diversity in practice. The required effective date of the standard for CMS Energy and Consumers is January 1, 2018, but early adoption is permitted. CMS Energy and Consumers elected to adopt the standard early for the year ended December 31, 2016. The standard addresses various cash flow issues, including debt prepayment and debt extinguishment costs. Under the new guidance, these costs, including premiums paid, should be classified as cash flows from financing activities. Previously, CMS Energy and Consumers classified premiums paid to retire debt early as cash flows from operating activities but, in accordance with this standard, they classified these payments as cash flows from financing activities for the year ended December 31, 2016. In addition, the standard requires that entities apply the new guidance retrospectively to all prior periods presented, unless impracticable. Accordingly, for the year ended December 31, 2014, CMS Energy reclassified $36 million and Consumers reclassified $16 million of debt retirement premium payments from operating activities to financing activities on their consolidated statements of cash flows. The standard had no other major impacts on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2016 ‑18, Restricted Cash: This standard 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. Under this guidance, the statement of cash flows should explain the total change in cash balances, including amounts described as restricted. The required effective date of the standard for CMS Energy and Consumers is January 1, 2018, but early adoption is permitted. CMS Energy and Consumers elected to adopt the standard early for the year ended December 31, 2016. In accordance with the standard, CMS Energy and Consumers included restricted cash amounts in their reconciliations of cash balances on their consolidated statements of cash flows for the year ended December 31, 2016. Previously, restricted cash amounts were excluded from the reconciliations of cash balances and transfers between cash balances and restricted cash balances were presented as other investing activities. 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  Years Ended December 31 2015 2014  CMS Energy, including Consumers  Increase (decrease) in:  Cash and cash equivalents, including restricted amounts, beginning of period $ 42 $ 32  Net cash used in investing activities (20) 10  Cash and cash equivalents, including restricted amounts, end of period 22 42  Consumers  Increase (decrease) in:  Cash and cash equivalents, including restricted amounts, beginning of period $ 41 $ 31  Net cash used in investing activities (20) 10  Cash and cash equivalents, including restricted amounts, end of period 21 41  For further information on CMS Energy’s and Consumers’ cash balances, see Note 17, Cash and Cash Equivalents. 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 have determined that they will not elect to adopt the standard early, but they are still assessing how they will apply the standard upon adoption. CMS Energy and Consumers are continuing to evaluate the impact of this standard on their consolidated financial statements; however, they have determined that the standard will have no impact on a majority of their revenues. The standard may require utility contributions in aid of construction to be treated as revenue, rather than as a reduction to the cost of plant, property, and equipment. Also, the standard may not permit revenue to be recognized for certain accounts for which collection is not deemed probable, which would represent a change from the existing practice of recognizing revenue at the billing rates, with associated expenses for uncollectible accounts. CMS Energy and Consumers do not presently expect that these two issues will have a material impact on their consolidated net income, cash flows, or financial position, but they are still assessing these issues and other requirements of the standard. 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 7, 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. See Note 10, Leases and Palisades Financing, for more information on CMS Energy’s and Consumers’ operating lease obligations. 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	2: New Accounting Standards Implementation of New Accounting Standards ASU 2014 ‑12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period: This standard, which was effective on January 1, 2016 for CMS Energy and Consumers, addresses stock awards with performance targets that can be met after an employee has completed the required service period. The standard was issued to resolve diversity in practice regarding the accounting treatment for this type of award. Under the new guidance, the probability of the performance target being met should be factored into compensation expense each period. This guidance is consistent with the accounting that CMS Energy and Consumers already applied to awards of this type. Therefore, the standard had no impact on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2015 ‑02, Amendments to the Consolidation Analysis: This standard, which was effective on January 1, 2016 for CMS Energy and Consumers, provides amended guidance on whether reporting entities should consolidate certain legal entities, including limited partnerships. CMS Energy and Consumers determined that the standard did not change any of their consolidation conclusions or have any impact on their consolidated net income, cash flows, or financial position. ASU 2015 ‑03, Simplifying the Presentation of Debt Issuance Costs: This standard, which was effective on January 1, 2016 for CMS Energy and Consumers, requires that debt issuance costs be presented as a direct deduction from the carrying amount of long-term debt on the balance sheet. Previously, debt issuance costs were reported as an asset. The new guidance aligns the presentation of debt issuance costs with debt discounts and premiums. In accordance with the standard, CMS Energy included $45 million and Consumers included $25 million of unamortized debt issuance costs in long-term debt on their consolidated balance sheets at December 31, 2016. In addition, this standard requires that entities apply the new guidance retrospectively to all prior periods presented. Accordingly, CMS Energy reclassified $41 million and Consumers reclassified $23 million of unamortized debt issuance costs from other non ‑current assets to long-term debt on their consolidated balance sheets at December 31, 2015. ASU 2016 ‑09, Improvements to Employee Share-Based Payment Accounting: This standard was issued to simplify and improve the accounting for employee share-based payment awards. The required effective date of the standard for CMS Energy and Consumers is January 1, 2017, but early adoption is permitted. CMS Energy and Consumers elected to adopt the standard early as of January 1, 2016. The standard requires all excess tax benefits and deficiencies that occur upon vesting of employee stock awards to be recognized in net income. Previously, CMS Energy and Consumers did not record excess tax benefits on restricted stock awards in net income but, under this standard, CMS Energy and Consumers recorded $7 million of excess tax benefits in net income for the year ended December 31, 2016. Also, in accordance with the standard, CMS Energy recorded a $33 million cumulative adjustment to its accumulated deficit at January 1, 2016. This amount represented excess federal tax benefits that CMS Energy had not recognized in prior periods due to the use of tax loss carryforwards. The implementation of this standard had no other major impacts on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2016 ‑15, Classification of Certain Cash Receipts and Cash Payments: This standard provides guidance on how certain cash receipts and cash payments should be classified in the statement of cash flows, with the objective of reducing diversity in practice. The required effective date of the standard for CMS Energy and Consumers is January 1, 2018, but early adoption is permitted. CMS Energy and Consumers elected to adopt the standard early for the year ended December 31, 2016. The standard addresses various cash flow issues, including debt prepayment and debt extinguishment costs. Under the new guidance, these costs, including premiums paid, should be classified as cash flows from financing activities. Previously, CMS Energy and Consumers classified premiums paid to retire debt early as cash flows from operating activities but, in accordance with this standard, they classified these payments as cash flows from financing activities for the year ended December 31, 2016. In addition, the standard requires that entities apply the new guidance retrospectively to all prior periods presented, unless impracticable. Accordingly, for the year ended December 31, 2014, CMS Energy reclassified $36 million and Consumers reclassified $16 million of debt retirement premium payments from operating activities to financing activities on their consolidated statements of cash flows. The standard had no other major impacts on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2016 ‑18, Restricted Cash: This standard 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. Under this guidance, the statement of cash flows should explain the total change in cash balances, including amounts described as restricted. The required effective date of the standard for CMS Energy and Consumers is January 1, 2018, but early adoption is permitted. CMS Energy and Consumers elected to adopt the standard early for the year ended December 31, 2016. In accordance with the standard, CMS Energy and Consumers included restricted cash amounts in their reconciliations of cash balances on their consolidated statements of cash flows for the year ended December 31, 2016. Previously, restricted cash amounts were excluded from the reconciliations of cash balances and transfers between cash balances and restricted cash balances were presented as other investing activities. 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  Years Ended December 31 2015 2014  CMS Energy, including Consumers  Increase (decrease) in:  Cash and cash equivalents, including restricted amounts, beginning of period $ 42 $ 32  Net cash used in investing activities (20) 10  Cash and cash equivalents, including restricted amounts, end of period 22 42  Consumers  Increase (decrease) in:  Cash and cash equivalents, including restricted amounts, beginning of period $ 41 $ 31  Net cash used in investing activities (20) 10  Cash and cash equivalents, including restricted amounts, end of period 21 41  For further information on CMS Energy’s and Consumers’ cash balances, see Note 17, Cash and Cash Equivalents. 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 have determined that they will not elect to adopt the standard early, but they are still assessing how they will apply the standard upon adoption. CMS Energy and Consumers are continuing to evaluate the impact of this standard on their consolidated financial statements; however, they have determined that the standard will have no impact on a majority of their revenues. The standard may require utility contributions in aid of construction to be treated as revenue, rather than as a reduction to the cost of plant, property, and equipment. Also, the standard may not permit revenue to be recognized for certain accounts for which collection is not deemed probable, which would represent a change from the existing practice of recognizing revenue at the billing rates, with associated expenses for uncollectible accounts. CMS Energy and Consumers do not presently expect that these two issues will have a material impact on their consolidated net income, cash flows, or financial position, but they are still assessing these issues and other requirements of the standard. 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 7, 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. See Note 10, Leases and Palisades Financing, for more information on CMS Energy’s and Consumers’ operating lease obligations. 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	12 Months Ended
	Dec. 31, 2016
Regulatory Matters	3: 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. Regulatory Assets and Liabilities Consumers is subject to the actions of the MPSC and FERC and therefore prepares its consolidated financial statements in accordance with the provisions of regulatory accounting. A utility must apply regulatory accounting when its rates are designed to recover specific costs of providing regulated services. Under regulatory accounting, Consumers records regulatory assets or liabilities for certain transactions that would have been treated as expense or revenue by non ‑regulated businesses. Presented in the following table are the regulatory assets and liabilities on Consumers’ consolidated balance sheets:    In Millions  December 31 End of Recovery or Refund Period 2016 2015  Regulatory assets  Current  Energy optimization plan incentive 1 2017 $ 17 $ 16  Total current regulatory assets $ 17 $ 16  Non-current  Postretirement benefits 2 various $ 1,373 $ 1,096  Securitized costs 3 2029 323 348  ARO 4 various 166 151  MGP sites 4 various 139 146  Unamortized loss on reacquired debt 4 various 54 61  Energy optimization plan incentive 1 2018 18 18  Gas storage inventory adjustments 4 various 14 18  Other various 4 2  Total non-current regulatory assets $ 2,091 $ 1,840  Total regulatory assets $ 2,108 $ 1,856  Regulatory liabilities  Current  Income taxes, net 2017 $ 64 $ 64  Reserve for customer refunds 2017 31 18  Total current regulatory liabilities $ 95 $ 82  Non-current  Cost of removal various $ 1,809 $ 1,745  Renewable energy plan 2028 83 109  ARO various 62 73  Renewable energy grant 2043 58 60  Energy optimization plan various 11 26  Income taxes, net various 7 64  Other various 11 11  Total non-current regulatory liabilities $ 2,041 $ 2,088  Total regulatory liabilities $ 2,136 $ 2,170  1 These regulatory assets have arisen from an alternative revenue program and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return. 2 This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return. 3 The MPSC has authorized a specific return on this regulatory asset. 4 These regulatory assets represent incurred costs for which the MPSC has provided, or Consumers expects, recovery without a return on investment. Regulatory Assets Energy Optimization Plan Incentive: In September 2016, the MPSC approved a settlement agreement authorizing Consumers to collect $18 million during 2017 as an incentive for exceeding its statutory savings targets in 2015 and for achieving certain other goals. Consumers recognized incentive revenue under this program of $18 million in 2015. Consumers also exceeded its statutory savings targets in 2016, and achieved certain other goals, and will request the MPSC’s approval to collect $18 million, the maximum performance incentive, in the energy optimization reconciliation to be filed in 2017. Consumers recognized incentive revenue under this program of $18 million in 2016. Postretirement Benefits: As part of the ratemaking process, the MPSC allows Consumers to recover the costs of postretirement benefits. Accordingly, Consumers defers the net impact of actuarial losses and gains as well as prior service costs and credits associated with postretirement benefits as a regulatory asset or liability. The asset or liability will decrease as the deferred items are amortized and recognized as components of net periodic benefit cost. For details about the amortization periods, see Note 12, Retirement Benefits. Securitized Costs: In 2013 , the MPSC issued a securitization financing order authorizing Consumers to issue securitization bonds in order to finance the recovery of the remaining book value of seven smaller coal-fueled electric generating units that Consumers retired in April 2016 and three smaller natural gas-fueled electric generating units that Consumers retired in June 2015 . Upon receipt of the MPSC’s order, Consumers removed the book value of the ten units from plant, property, and equipment and recorded this amount as a regulatory asset. Consumers is amortizing the regulatory asset over the life of the related securitization bonds, which it issued through a subsidiary in 2014. For additional details regarding the securitization bonds, see Note 5, Financings and Capitalization. ARO: The recovery of the underlying asset investments and related removal and monitoring costs of recorded AROs is approved by the MPSC in depreciation rate cases. Consumers records a regulatory asset and a regulatory liability for timing differences between the recognition of AROs for financial reporting purposes and the recovery of these costs from customers. The recovery period approximates the useful life of the assets to be removed. MGP Sites: Consumers is incurring environmental remediation and other response activity costs at 23 former MGP facilities. The MPSC allows Consumers to recover from its natural gas customers over a ten -year period the costs incurred to remediate the MGP sites. Unamortized Loss on Reacquired Debt: Under regulatory accounting, any unamortized discount, premium, or expense related to debt redeemed with the proceeds of new debt is capitalized and amortized over the life of the new debt. Gas Storage Inventory Adjustments: Consumers incurs inventory expenses related to the loss of gas from its natural gas storage fields. The MPSC allows Consumers to recover these costs from its natural gas customers over a five -year period. Regulatory Liabilities Income Taxes, Net: These costs represent the difference between deferred income taxes recognized for financial reporting purposes and amounts previously reflected in Consumers’ rates. This net balance will decrease over the remaining life of the related temporary differences and flow through current income tax benefit. In 2013, the MPSC issued an order authorizing Consumers to accelerate the flow-through to electric and gas customers of certain income tax benefits associated primarily with the cost of removal of plant placed in service before 1993. The order authorized Consumers to implement a regulatory treatment beginning January 2014 that will return $ 209 million of income tax benefits over five years to electric customers and $ 260 million of income tax benefits over 12 years to gas customers. During 2016 , Consumers returned $64 million of income tax benefits to customers. Reserve for Customer Refunds: Consumers had recorded reserves for customer refunds of $31 million at December 31, 2016 and $18 million at December 31, 2015. At December 31, 2016, the majority of the balance related to self-implemented electric and gas rates. At December 31, 2015, the amount recorded included a $14 million regulatory liability related to the overcollection during 2015 of surcharges related to securitization bonds that Consumers issued in 2001 and retired in 2015. Consumers refunded this amount to customers in 2016. Cost of Removal: These amounts have been collected from customers to fund future asset removal activities. This regulatory liability is reduced as costs of removal are incurred. The refund period of this regulatory liability approximates the useful life of the assets to be removed. Renewable Energy Plan: Consumers has collected surcharges to fund its renewable energy plan. Amounts not yet spent under the plan are recorded as a regulatory liability, which is amortized as incremental costs are incurred to operate and depreciate Consumers’ wind parks and to purchase RECs under renewable energy purchase agreements. Incremental costs represent costs incurred in excess of amounts recovered through the PSCR process. Renewable Energy Grant: In 2013, Consumers received a $ 69 million renewable energy grant for Lake Winds ® Energy Park, which began operations in 2012. This grant reduces Consumers’ cost of complying with Michigan’s renewable portfolio standard and, accordingly, reduces the overall renewable energy surcharge to be collected from customers. The regulatory liability recorded for the grant will be amortized over the life of Lake Winds ® Energy Park. Energy Optimization Plan: At December 31, 2016 and 2015 , surcharges collected from customers to fund Consumers’ energy optimization plan exceeded Consumers’ spending. The associated regulatory liability is amortized as costs are incurred under Consumers’ energy optimization plan. Consumers Electric Utility 2014 Electric Rate Case: In December 2014, Consumers filed an application with the MPSC seeking an annual rate increase of $163 million, and in June 2015, Consumers self-implemented an annual rate increase of $110 million, subject to refund with interest. The MPSC issued an order in November 2015, authorizing an annual rate increase of $165 million, based on a 10.3 percent authorized rate of return on equity. In April 2016, upon the retirement of seven coal-fueled electric generating units, the annual rate increase was reduced to $126 million. In February 2016, Consumers filed a reconciliation of total revenues collected during self-implementation to those that would have been collected under final rates. In June 2016, the MPSC approved a settlement agreement that resulted in a $1 million refund to customers. 2016 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. The filing requested authority to recover new investment in system reliability, environmental compliance, and technology enhancements. Presented in the following table are the components of the requested increase in revenue:    In Millions  Components of the rate increase  Investment in rate base $ 161  Operating and maintenance costs 21  Gross margin 17  Cost of capital 15  Working capital 11  Total $ 225  The filing also seeks approval of an investment recovery mechanism that would provide for additional annual rate increases of $38 million beginning in 2017, $92 million beginning in 2018, and $92 million beginning in 2019 for incremental investments that Consumers plans to make in those years, subject to reconciliation. In September 2016, Consumers self ‑implemented an annual rate increase of $170 million, subject to refund with interest. In October 2016, Consumers reduced its requested annual rate increase to $208 million. Consumers had a recorded reserve for customer refunds at December 31, 2016 that it believes is adequate. Consumers Gas Utility Gas Rate Case: In July 2015, Consumers filed an application with the MPSC seeking an annual rate increase of $85 million, based on a 10.7 percent authorized return on equity. In January 2016, Consumers self-implemented an annual rate increase of $60 million, subject to refund with interest. In April 2016, the MPSC approved a settlement agreement authorizing a $40 million annual rate increase. In July 2016, Consumers filed a reconciliation of total revenues collected during self-implementation to those that would have been collected under final rates. In November 2016, the MPSC approved a settlement agreement that resulted in a $10 million refund to customers, which Consumers had recorded as a reserve for customer refunds at December 31, 2016. Power Supply Cost Recovery and Gas Cost Recovery The PSCR and GCR ratemaking processes are designed to allow Consumers to recover all of its power supply and purchased natural gas costs if incurred under reasonable and prudent policies and practices. The MPSC reviews these costs, policies, and practices in annual plan and reconciliation proceedings. Consumers adjusts its PSCR and GCR billing charges monthly in order to minimize the underrecovery or overrecovery amount in the annual reconciliations. Underrecoveries represent probable future revenues that will be recovered from customers; overrecoveries represent previously collected revenues that will be refunded to customers. Presented in the following table are the liabilities for PSCR and GCR overrecoveries reflected on Consumers’ consolidated balance sheets:    In Millions  December 31 2016 2015  Liabilities  PSCR overrecoveries $ 8 $ 8  GCR overrecoveries 13 18  Accrued rate refunds $ 21 $ 26  PSCR Plans and Reconciliations: In May 2016, the MPSC issued an order in Consumers’ 2013 PSCR reconciliation, approving full recovery of $1.9 billion of power costs and authorizing Consumers to reflect in its 2014 PSCR plan the overrecovery of $9 million. In May 2016, the MPSC issued an order in Consumers’ 2014 PSCR plan, authorizing the 2014 PSCR factor that Consumers self-implemented beginning in January 2014 and then revised in July 2014 following severe winter weather during the three months ended March 31, 2014. In July 2016, the MPSC issued an order in Consumers’ 2014 PSCR reconciliation, approving full recovery of $2.1 billion of power costs and authorizing Consumers to reflect in its 2015 PSCR plan the overrecovery of $5 million. In June 2016, the MPSC issued an order in Consumers’ 2015 PSCR plan, authorizing the 2015 PSCR factor that Consumers self-implemented beginning in January 2015. In March 2016, Consumers filed its 2015 PSCR reconciliation, requesting full recovery of $1.9 billion of power costs and authorization to reflect in its 2016 PSCR plan the overrecovery of $6 million. In October 2016, the MPSC approved Consumers’ 2016 PSCR plan, with the exception of the recovery of litigation costs related to a complaint that Consumers filed against a rail transportation company, and adjusted the 2016 PSCR factor that Consumers self-implemented in January 2016. In its order, the MPSC indicated that the litigation costs could be included for consideration in a general rate case. In connection with this disallowance, Consumers recognized a charge of $6 million related to litigation costs incurred during 2015 and 2016. GCR Plans and Reconciliations: In July 2016, the MPSC issued an order in Consumers’ 2013-2014 GCR reconciliation, approving full recovery of $0.9 billion of gas costs and authorizing Consumers to reflect in its 2014-2015 GCR plan the underrecovery of $84 million. In September 2016, the MPSC issued an order in Consumers 2014-2015 GCR reconciliation, approving full recovery of $0.8 billion of gas costs and authorizing Consumers to reflect in its 2015-2016 GCR plan the overrecovery of $9 million. In May 2016, the MPSC issued an order in Consumers’ 2015-2016 GCR plan, revising the 2015-2016 GCR factor that Consumers self-implemented beginning in April 2015. Consumers filed its 2015-2016 GCR reconciliation in June 2016, requesting full recovery of $0.5 billion of gas costs and authorization to reflect in its 2016-2017 GCR plan the overrecovery of $2 million. In November 2016, the MPSC issued an order in Consumers’ 2016-2017 GCR plan, authorizing the 2016-2017 GCR factor that Consumers self-implemented beginning in April 2016.
Consumers Energy Company [Member]
Regulatory Matters	3: 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. Regulatory Assets and Liabilities Consumers is subject to the actions of the MPSC and FERC and therefore prepares its consolidated financial statements in accordance with the provisions of regulatory accounting. A utility must apply regulatory accounting when its rates are designed to recover specific costs of providing regulated services. Under regulatory accounting, Consumers records regulatory assets or liabilities for certain transactions that would have been treated as expense or revenue by non ‑regulated businesses. Presented in the following table are the regulatory assets and liabilities on Consumers’ consolidated balance sheets:    In Millions  December 31 End of Recovery or Refund Period 2016 2015  Regulatory assets  Current  Energy optimization plan incentive 1 2017 $ 17 $ 16  Total current regulatory assets $ 17 $ 16  Non-current  Postretirement benefits 2 various $ 1,373 $ 1,096  Securitized costs 3 2029 323 348  ARO 4 various 166 151  MGP sites 4 various 139 146  Unamortized loss on reacquired debt 4 various 54 61  Energy optimization plan incentive 1 2018 18 18  Gas storage inventory adjustments 4 various 14 18  Other various 4 2  Total non-current regulatory assets $ 2,091 $ 1,840  Total regulatory assets $ 2,108 $ 1,856  Regulatory liabilities  Current  Income taxes, net 2017 $ 64 $ 64  Reserve for customer refunds 2017 31 18  Total current regulatory liabilities $ 95 $ 82  Non-current  Cost of removal various $ 1,809 $ 1,745  Renewable energy plan 2028 83 109  ARO various 62 73  Renewable energy grant 2043 58 60  Energy optimization plan various 11 26  Income taxes, net various 7 64  Other various 11 11  Total non-current regulatory liabilities $ 2,041 $ 2,088  Total regulatory liabilities $ 2,136 $ 2,170  1 These regulatory assets have arisen from an alternative revenue program and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return. 2 This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return. 3 The MPSC has authorized a specific return on this regulatory asset. 4 These regulatory assets represent incurred costs for which the MPSC has provided, or Consumers expects, recovery without a return on investment. Regulatory Assets Energy Optimization Plan Incentive: In September 2016, the MPSC approved a settlement agreement authorizing Consumers to collect $18 million during 2017 as an incentive for exceeding its statutory savings targets in 2015 and for achieving certain other goals. Consumers recognized incentive revenue under this program of $18 million in 2015. Consumers also exceeded its statutory savings targets in 2016, and achieved certain other goals, and will request the MPSC’s approval to collect $18 million, the maximum performance incentive, in the energy optimization reconciliation to be filed in 2017. Consumers recognized incentive revenue under this program of $18 million in 2016. Postretirement Benefits: As part of the ratemaking process, the MPSC allows Consumers to recover the costs of postretirement benefits. Accordingly, Consumers defers the net impact of actuarial losses and gains as well as prior service costs and credits associated with postretirement benefits as a regulatory asset or liability. The asset or liability will decrease as the deferred items are amortized and recognized as components of net periodic benefit cost. For details about the amortization periods, see Note 12, Retirement Benefits. Securitized Costs: In 2013 , the MPSC issued a securitization financing order authorizing Consumers to issue securitization bonds in order to finance the recovery of the remaining book value of seven smaller coal-fueled electric generating units that Consumers retired in April 2016 and three smaller natural gas-fueled electric generating units that Consumers retired in June 2015 . Upon receipt of the MPSC’s order, Consumers removed the book value of the ten units from plant, property, and equipment and recorded this amount as a regulatory asset. Consumers is amortizing the regulatory asset over the life of the related securitization bonds, which it issued through a subsidiary in 2014. For additional details regarding the securitization bonds, see Note 5, Financings and Capitalization. ARO: The recovery of the underlying asset investments and related removal and monitoring costs of recorded AROs is approved by the MPSC in depreciation rate cases. Consumers records a regulatory asset and a regulatory liability for timing differences between the recognition of AROs for financial reporting purposes and the recovery of these costs from customers. The recovery period approximates the useful life of the assets to be removed. MGP Sites: Consumers is incurring environmental remediation and other response activity costs at 23 former MGP facilities. The MPSC allows Consumers to recover from its natural gas customers over a ten -year period the costs incurred to remediate the MGP sites. Unamortized Loss on Reacquired Debt: Under regulatory accounting, any unamortized discount, premium, or expense related to debt redeemed with the proceeds of new debt is capitalized and amortized over the life of the new debt. Gas Storage Inventory Adjustments: Consumers incurs inventory expenses related to the loss of gas from its natural gas storage fields. The MPSC allows Consumers to recover these costs from its natural gas customers over a five -year period. Regulatory Liabilities Income Taxes, Net: These costs represent the difference between deferred income taxes recognized for financial reporting purposes and amounts previously reflected in Consumers’ rates. This net balance will decrease over the remaining life of the related temporary differences and flow through current income tax benefit. In 2013, the MPSC issued an order authorizing Consumers to accelerate the flow-through to electric and gas customers of certain income tax benefits associated primarily with the cost of removal of plant placed in service before 1993. The order authorized Consumers to implement a regulatory treatment beginning January 2014 that will return $ 209 million of income tax benefits over five years to electric customers and $ 260 million of income tax benefits over 12 years to gas customers. During 2016 , Consumers returned $64 million of income tax benefits to customers. Reserve for Customer Refunds: Consumers had recorded reserves for customer refunds of $31 million at December 31, 2016 and $18 million at December 31, 2015. At December 31, 2016, the majority of the balance related to self-implemented electric and gas rates. At December 31, 2015, the amount recorded included a $14 million regulatory liability related to the overcollection during 2015 of surcharges related to securitization bonds that Consumers issued in 2001 and retired in 2015. Consumers refunded this amount to customers in 2016. Cost of Removal: These amounts have been collected from customers to fund future asset removal activities. This regulatory liability is reduced as costs of removal are incurred. The refund period of this regulatory liability approximates the useful life of the assets to be removed. Renewable Energy Plan: Consumers has collected surcharges to fund its renewable energy plan. Amounts not yet spent under the plan are recorded as a regulatory liability, which is amortized as incremental costs are incurred to operate and depreciate Consumers’ wind parks and to purchase RECs under renewable energy purchase agreements. Incremental costs represent costs incurred in excess of amounts recovered through the PSCR process. Renewable Energy Grant: In 2013, Consumers received a $ 69 million renewable energy grant for Lake Winds ® Energy Park, which began operations in 2012. This grant reduces Consumers’ cost of complying with Michigan’s renewable portfolio standard and, accordingly, reduces the overall renewable energy surcharge to be collected from customers. The regulatory liability recorded for the grant will be amortized over the life of Lake Winds ® Energy Park. Energy Optimization Plan: At December 31, 2016 and 2015 , surcharges collected from customers to fund Consumers’ energy optimization plan exceeded Consumers’ spending. The associated regulatory liability is amortized as costs are incurred under Consumers’ energy optimization plan. Consumers Electric Utility 2014 Electric Rate Case: In December 2014, Consumers filed an application with the MPSC seeking an annual rate increase of $163 million, and in June 2015, Consumers self-implemented an annual rate increase of $110 million, subject to refund with interest. The MPSC issued an order in November 2015, authorizing an annual rate increase of $165 million, based on a 10.3 percent authorized rate of return on equity. In April 2016, upon the retirement of seven coal-fueled electric generating units, the annual rate increase was reduced to $126 million. In February 2016, Consumers filed a reconciliation of total revenues collected during self-implementation to those that would have been collected under final rates. In June 2016, the MPSC approved a settlement agreement that resulted in a $1 million refund to customers. 2016 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. The filing requested authority to recover new investment in system reliability, environmental compliance, and technology enhancements. Presented in the following table are the components of the requested increase in revenue:    In Millions  Components of the rate increase  Investment in rate base $ 161  Operating and maintenance costs 21  Gross margin 17  Cost of capital 15  Working capital 11  Total $ 225  The filing also seeks approval of an investment recovery mechanism that would provide for additional annual rate increases of $38 million beginning in 2017, $92 million beginning in 2018, and $92 million beginning in 2019 for incremental investments that Consumers plans to make in those years, subject to reconciliation. In September 2016, Consumers self ‑implemented an annual rate increase of $170 million, subject to refund with interest. In October 2016, Consumers reduced its requested annual rate increase to $208 million. Consumers had a recorded reserve for customer refunds at December 31, 2016 that it believes is adequate. Consumers Gas Utility Gas Rate Case: In July 2015, Consumers filed an application with the MPSC seeking an annual rate increase of $85 million, based on a 10.7 percent authorized return on equity. In January 2016, Consumers self-implemented an annual rate increase of $60 million, subject to refund with interest. In April 2016, the MPSC approved a settlement agreement authorizing a $40 million annual rate increase. In July 2016, Consumers filed a reconciliation of total revenues collected during self-implementation to those that would have been collected under final rates. In November 2016, the MPSC approved a settlement agreement that resulted in a $10 million refund to customers, which Consumers had recorded as a reserve for customer refunds at December 31, 2016. Power Supply Cost Recovery and Gas Cost Recovery The PSCR and GCR ratemaking processes are designed to allow Consumers to recover all of its power supply and purchased natural gas costs if incurred under reasonable and prudent policies and practices. The MPSC reviews these costs, policies, and practices in annual plan and reconciliation proceedings. Consumers adjusts its PSCR and GCR billing charges monthly in order to minimize the underrecovery or overrecovery amount in the annual reconciliations. Underrecoveries represent probable future revenues that will be recovered from customers; overrecoveries represent previously collected revenues that will be refunded to customers. Presented in the following table are the liabilities for PSCR and GCR overrecoveries reflected on Consumers’ consolidated balance sheets:    In Millions  December 31 2016 2015  Liabilities  PSCR overrecoveries $ 8 $ 8  GCR overrecoveries 13 18  Accrued rate refunds $ 21 $ 26  PSCR Plans and Reconciliations: In May 2016, the MPSC issued an order in Consumers’ 2013 PSCR reconciliation, approving full recovery of $1.9 billion of power costs and authorizing Consumers to reflect in its 2014 PSCR plan the overrecovery of $9 million. In May 2016, the MPSC issued an order in Consumers’ 2014 PSCR plan, authorizing the 2014 PSCR factor that Consumers self-implemented beginning in January 2014 and then revised in July 2014 following severe winter weather during the three months ended March 31, 2014. In July 2016, the MPSC issued an order in Consumers’ 2014 PSCR reconciliation, approving full recovery of $2.1 billion of power costs and authorizing Consumers to reflect in its 2015 PSCR plan the overrecovery of $5 million. In June 2016, the MPSC issued an order in Consumers’ 2015 PSCR plan, authorizing the 2015 PSCR factor that Consumers self-implemented beginning in January 2015. In March 2016, Consumers filed its 2015 PSCR reconciliation, requesting full recovery of $1.9 billion of power costs and authorization to reflect in its 2016 PSCR plan the overrecovery of $6 million. In October 2016, the MPSC approved Consumers’ 2016 PSCR plan, with the exception of the recovery of litigation costs related to a complaint that Consumers filed against a rail transportation company, and adjusted the 2016 PSCR factor that Consumers self-implemented in January 2016. In its order, the MPSC indicated that the litigation costs could be included for consideration in a general rate case. In connection with this disallowance, Consumers recognized a charge of $6 million related to litigation costs incurred during 2015 and 2016. GCR Plans and Reconciliations: In July 2016, the MPSC issued an order in Consumers’ 2013-2014 GCR reconciliation, approving full recovery of $0.9 billion of gas costs and authorizing Consumers to reflect in its 2014-2015 GCR plan the underrecovery of $84 million. In September 2016, the MPSC issued an order in Consumers 2014-2015 GCR reconciliation, approving full recovery of $0.8 billion of gas costs and authorizing Consumers to reflect in its 2015-2016 GCR plan the overrecovery of $9 million. In May 2016, the MPSC issued an order in Consumers’ 2015-2016 GCR plan, revising the 2015-2016 GCR factor that Consumers self-implemented beginning in April 2015. Consumers filed its 2015-2016 GCR reconciliation in June 2016, requesting full recovery of $0.5 billion of gas costs and authorization to reflect in its 2016-2017 GCR plan the overrecovery of $2 million. In November 2016, the MPSC issued an order in Consumers’ 2016-2017 GCR plan, authorizing the 2016-2017 GCR factor that Consumers self-implemented beginning in April 2016.

Contingencies And Commitments

Contingencies And Commitments	12 Months Ended
	Dec. 31, 2016
Contingencies And Commitments	4: 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. The following provides more detail on the cases in which CMS Energy or its affiliates were named as parties: · In 2005, CMS Energy, CMS MST, and CMS Field Services were named as defendants in a putative class action filed in Kansas state court, Learjet, Inc., et al. v. Oneok, Inc., et al. The complaint alleges that during the pu tative class period, January 2000 through October 2002, the defendants engaged in a scheme to violate the Kansas Restraint of Trade Act. The plaintiffs are seeking treble damages, statutory full consideration damages consisting of the full consideration paid by the plaintiffs for natural gas purchased during the period, costs, and attorneys’ fees. · In 2007, a class action complaint, Heartland Regional Medical Center, et al. v. Oneok, Inc. et al., was filed as a putative class action in Missouri state court alleging violations of Missouri antitrust laws. The defendants, including CMS Energy, CMS Field Services, and CMS MST, are alleged to have violated the Missouri antitrust law in connection with their natural gas reporting activities during the period January 2000 through October 2002. The plaintiffs are seeking treble damages, costs, and attorneys’ fees. · In 2006, a class action complaint, Arandell Corp., et al. v. XCEL Energy Inc., et al., was filed in Wisconsin state court on behalf of Wisconsin commercial entities that purchased natural gas between January 2000 and October 2002. The defendants, including CMS Energy, CMS ERM, and Cantera Gas Company, are alleged to have violated Wisconsin’s antitrust statute. The plaintiffs are seeking full consideration damages, treble damages, costs, interest, and attorneys’ fees. · In 2009, a class action complaint, Newpage Wisconsin System v. CMS ERM, et al., was filed in circuit court in Wood County, Wisconsin, against CMS Energy, CMS ERM, Cantera Gas Company, and others. The plaintiff is seeking full consideration damages, treble damages, costs, interest, and attorneys’ fees. · In 2005, J.P. Morgan Trust Company, N.A., in its capacity as trustee of the FLI Liquidating Trust, filed an action in Kansas state court against CMS Energy, CMS MST, CMS Field Services, and others. The complaint alleges various claims under the Kansas Restraint of Trade Act. The plaintiff is seeking statutory full consideration damages for its purchases of natural gas in 2000 and 2001, costs, and attorneys’ fees. After removal to federal court, all of the cases described above 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. Plaintiffs filed appeals in all of the cases. The issues on appeal were whether the district court erred in dismissing the cases based on FERC preemption and denying the plaintiffs’ motions for leave to amend their complaints to add a federal Sherman Act antitrust claim. 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 tentative settlement with the plaintiffs in the three Kansas and Missouri cases for an amount that was not material to CMS Energy. Notice of the tentative settlement has been filed in the federal district court. The settlement will be subject to court approval. Other CMS Energy entities remain as defendants in the two Wisconsin class action lawsuits. 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 December 31, 20 16 , CMS Energy had a recorded liability of $ 51 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 $ 65 million. CMS Energy expects to pay the following amounts for long-term liquid disposal and operating and maintenance in each of the next five years:    In Millions  2017 2018 2019 2020 2021  CMS Energy  Long-term liquid disposal and operating and maintenance costs $ 5 $ 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 CMS Energy owes $ 152 million in taxes, plus significant penalties and interest, in connection with the sale. 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 December 31, 20 16 , 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 December 31, 20 16 , 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 December 31, 20 16 , Consumers had a recorded liability of $ 107 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 $ 117 million. Consumers expects to pay the following amounts for remediation and other response activity costs in each of the next five years:    In Millions  2017 2018 2019 2020 2021  Consumers  Remediation and other response activity costs $ 35 $ 14 $ 19 $ 10 $ 5  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 December 31, 20 16 , Consumers had a regulatory asset of $139 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 December 31, 20 16 , 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 and Consumers’ guarantees at December 31, 20 16 :    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 48 -  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. For additional details on this guarantee, see Note 20, Variable Interest Entities. 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 Michigan Sales and Use Tax Litigation: In 2010, the Michigan Department of Treasury finalized a sales and use tax audit of Consumers for the period from October 1997 through December 2004. It determined that Consumers’ electric distribution equipment and its natural gas system were not eligible for an industrial-processing exemption and therefore were subject to the use tax. Consumers paid the tax for the period from 1997 through 2004 and filed a claim in the Michigan Court of Claims disputing the tax determination. Consumers continued to apply the industrial-processing exemption for the years subsequent to 2004. In December 2015 and June 2016, Consumers and the Michigan Department of Treasury reached settlement s under which the Michigan Department of Treasury agreed to refund to Consumers $60 million of use tax that Consumers paid on its electric distribution equipment and its natural gas system from 1997 thr ough 2015. This amount comprised a $42 million refund of taxes paid, a $12 million refund of interest paid, and $6 million of interest owed to Consumers. In December 2015, Consumers recognized the 2015 settlement, which totaled $37 million, in its consolidated financial statements. Accordingly, Consumers recorded a $12 million reduction in other interest expense, $6 million in interest income, and a $19 million reduction in plant, property, and equipment for the portion of the taxes paid that had originally been capitalized as a cost of equipment. Consumers also recorded an additional $5 million reduction in general taxes for the elimination of a loss contingency previously recorded for this matter. In June 2016, Consumers received $13 million of the total settlement amount and recorded a note receivable for the remainder, of which $30 million will be received in 2017 and $17 million in 2018. Also in June 2016, Consumers recorded a $4 million reduction in maintenance and other operating expenses, and the remainder of the settlement amount as a reduction in plant, property, and equipment for the portion of the taxes paid that had originally been capitalized as a cost of equipment. Concurrently with the June 2016 sales and use tax settlement, CMS Energy reached agreement with the Michigan Department of Treasury on two other tax matters that were under dispute relating to Michigan Corporate Income Tax and Michigan Single Business T ax. As a result, CMS Energy recognized a $3 million reduction in income tax expense and a $3 million reduction in general taxes. Other: In addition to the matters disclosed in this Note and Note 3, 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. Contractual Commitments Purchase Obligations: Purchase obligations arise from long-term contracts for the purchase of commodities and related services, and construction and service agreements. The commodities and related services include long-term PPAs, natural gas and associated transportation, and coal and associated transportation. Related - party PPAs are between Consumers and certain affiliates of CMS Enterprises. Presented in the following table are CMS Energy’s and Consumers’ contractual purchase obligations at December 31, 20 16 for each of the periods shown:    In Millions  Payments Due  Total 2017 2018 2019 2020 2021 Beyond 2021  CMS Energy, including Consumers  Total PPAs $ 9,356 $ 1,008 $ 1,031 $ 1,021 $ 1,051 $ 1,044 $ 4,201  Other 1,922 931 376 187 132 32 264  Consumers  PPAs  MCV PPA $ 3,010 $ 326 $ 331 $ 330 $ 344 $ 325 $ 1,354  Palisades PPA 1,994 354 365 376 388 398 113  Related-party PPAs 899 81 82 86 88 88 474  Other PPAs 3,453 247 253 229 231 233 2,260  Total PPAs $ 9,356 $ 1,008 $ 1,031 $ 1,021 $ 1,051 $ 1,044 $ 4,201  Other 1,651 895 347 157 102 19 131  MCV PPA: Consumers has a 35 ‑year PPA that began in 1990 with the MCV Partnership to purchase 1,240 MW of electricity. The MCV PPA, as amended and restated, provides for: · a capacity charge of $ 10.14 per MWh of available capacity · a fixed energy charge based on Consumers’ annual average baseload coal generating plant operating and maintenance cost, fuel inventory, and administrative and general expenses · a variable energy charge based on the MCV Partnership’s cost of production when the plant is dispatched · a $ 5 million annual contribution by the MCV Partnership to a renewable resources program · an option for Consumers to extend the MCV PPA for five years or purchase the MCV Facility at the conclusion of the MCV PPA’s term in March 2025 Capacity and energy charges under the MCV PPA were $ 305 million in 2016 , $ 282 million in 2015 , and $ 300 million in 2014 . Palisades PPA: Consumers has a PPA expiring in 2022 with Entergy to purchase virtually all of the capacity and energy produced by Palisades, up to the annual average capacity of 798 MW. For all delivered energy, the Palisades PPA has escalating capacity and variable energy charges. Total capacity and energy charges under the Palisades PPA were $ 363 million in 2016 , $ 352 million in 2015 , and $ 302 million in 2014 . In December 2016, Consumers and Entergy reached an agreement to terminate the PPA in May 2018 , subject to timely receipt of certain MPSC approvals . The payments due reflect the original terms of the PPA. For further details about Palisades, see Note 10, Leases and Palisades Financing. Other PPAs: Consumers has PPAs expiring through 2036 with various counterparties. The majority of the PPAs have capacity and energy charges for delivered energy. Capacity and energy charges under these PPAs were $348 million in 2016 , $347 million in 2015 , and $354 million in 2014 .
Consumers Energy Company [Member]
Contingencies And Commitments	4: 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. The following provides more detail on the cases in which CMS Energy or its affiliates were named as parties: · In 2005, CMS Energy, CMS MST, and CMS Field Services were named as defendants in a putative class action filed in Kansas state court, Learjet, Inc., et al. v. Oneok, Inc., et al. The complaint alleges that during the pu tative class period, January 2000 through October 2002, the defendants engaged in a scheme to violate the Kansas Restraint of Trade Act. The plaintiffs are seeking treble damages, statutory full consideration damages consisting of the full consideration paid by the plaintiffs for natural gas purchased during the period, costs, and attorneys’ fees. · In 2007, a class action complaint, Heartland Regional Medical Center, et al. v. Oneok, Inc. et al., was filed as a putative class action in Missouri state court alleging violations of Missouri antitrust laws. The defendants, including CMS Energy, CMS Field Services, and CMS MST, are alleged to have violated the Missouri antitrust law in connection with their natural gas reporting activities during the period January 2000 through October 2002. The plaintiffs are seeking treble damages, costs, and attorneys’ fees. · In 2006, a class action complaint, Arandell Corp., et al. v. XCEL Energy Inc., et al., was filed in Wisconsin state court on behalf of Wisconsin commercial entities that purchased natural gas between January 2000 and October 2002. The defendants, including CMS Energy, CMS ERM, and Cantera Gas Company, are alleged to have violated Wisconsin’s antitrust statute. The plaintiffs are seeking full consideration damages, treble damages, costs, interest, and attorneys’ fees. · In 2009, a class action complaint, Newpage Wisconsin System v. CMS ERM, et al., was filed in circuit court in Wood County, Wisconsin, against CMS Energy, CMS ERM, Cantera Gas Company, and others. The plaintiff is seeking full consideration damages, treble damages, costs, interest, and attorneys’ fees. · In 2005, J.P. Morgan Trust Company, N.A., in its capacity as trustee of the FLI Liquidating Trust, filed an action in Kansas state court against CMS Energy, CMS MST, CMS Field Services, and others. The complaint alleges various claims under the Kansas Restraint of Trade Act. The plaintiff is seeking statutory full consideration damages for its purchases of natural gas in 2000 and 2001, costs, and attorneys’ fees. After removal to federal court, all of the cases described above 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. Plaintiffs filed appeals in all of the cases. The issues on appeal were whether the district court erred in dismissing the cases based on FERC preemption and denying the plaintiffs’ motions for leave to amend their complaints to add a federal Sherman Act antitrust claim. 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 tentative settlement with the plaintiffs in the three Kansas and Missouri cases for an amount that was not material to CMS Energy. Notice of the tentative settlement has been filed in the federal district court. The settlement will be subject to court approval. Other CMS Energy entities remain as defendants in the two Wisconsin class action lawsuits. 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 December 31, 20 16 , CMS Energy had a recorded liability of $ 51 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 $ 65 million. CMS Energy expects to pay the following amounts for long-term liquid disposal and operating and maintenance in each of the next five years:    In Millions  2017 2018 2019 2020 2021  CMS Energy  Long-term liquid disposal and operating and maintenance costs $ 5 $ 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 CMS Energy owes $ 152 million in taxes, plus significant penalties and interest, in connection with the sale. 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 December 31, 20 16 , 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 December 31, 20 16 , 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 December 31, 20 16 , Consumers had a recorded liability of $ 107 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 $ 117 million. Consumers expects to pay the following amounts for remediation and other response activity costs in each of the next five years:    In Millions  2017 2018 2019 2020 2021  Consumers  Remediation and other response activity costs $ 35 $ 14 $ 19 $ 10 $ 5  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 December 31, 20 16 , Consumers had a regulatory asset of $139 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 December 31, 20 16 , 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 and Consumers’ guarantees at December 31, 20 16 :    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 48 -  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. For additional details on this guarantee, see Note 20, Variable Interest Entities. 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 Michigan Sales and Use Tax Litigation: In 2010, the Michigan Department of Treasury finalized a sales and use tax audit of Consumers for the period from October 1997 through December 2004. It determined that Consumers’ electric distribution equipment and its natural gas system were not eligible for an industrial-processing exemption and therefore were subject to the use tax. Consumers paid the tax for the period from 1997 through 2004 and filed a claim in the Michigan Court of Claims disputing the tax determination. Consumers continued to apply the industrial-processing exemption for the years subsequent to 2004. In December 2015 and June 2016, Consumers and the Michigan Department of Treasury reached settlement s under which the Michigan Department of Treasury agreed to refund to Consumers $60 million of use tax that Consumers paid on its electric distribution equipment and its natural gas system from 1997 thr ough 2015. This amount comprised a $42 million refund of taxes paid, a $12 million refund of interest paid, and $6 million of interest owed to Consumers. In December 2015, Consumers recognized the 2015 settlement, which totaled $37 million, in its consolidated financial statements. Accordingly, Consumers recorded a $12 million reduction in other interest expense, $6 million in interest income, and a $19 million reduction in plant, property, and equipment for the portion of the taxes paid that had originally been capitalized as a cost of equipment. Consumers also recorded an additional $5 million reduction in general taxes for the elimination of a loss contingency previously recorded for this matter. In June 2016, Consumers received $13 million of the total settlement amount and recorded a note receivable for the remainder, of which $30 million will be received in 2017 and $17 million in 2018. Also in June 2016, Consumers recorded a $4 million reduction in maintenance and other operating expenses, and the remainder of the settlement amount as a reduction in plant, property, and equipment for the portion of the taxes paid that had originally been capitalized as a cost of equipment. Concurrently with the June 2016 sales and use tax settlement, CMS Energy reached agreement with the Michigan Department of Treasury on two other tax matters that were under dispute relating to Michigan Corporate Income Tax and Michigan Single Business T ax. As a result, CMS Energy recognized a $3 million reduction in income tax expense and a $3 million reduction in general taxes. Other: In addition to the matters disclosed in this Note and Note 3, 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. Contractual Commitments Purchase Obligations: Purchase obligations arise from long-term contracts for the purchase of commodities and related services, and construction and service agreements. The commodities and related services include long-term PPAs, natural gas and associated transportation, and coal and associated transportation. Related - party PPAs are between Consumers and certain affiliates of CMS Enterprises. Presented in the following table are CMS Energy’s and Consumers’ contractual purchase obligations at December 31, 20 16 for each of the periods shown:    In Millions  Payments Due  Total 2017 2018 2019 2020 2021 Beyond 2021  CMS Energy, including Consumers  Total PPAs $ 9,356 $ 1,008 $ 1,031 $ 1,021 $ 1,051 $ 1,044 $ 4,201  Other 1,922 931 376 187 132 32 264  Consumers  PPAs  MCV PPA $ 3,010 $ 326 $ 331 $ 330 $ 344 $ 325 $ 1,354  Palisades PPA 1,994 354 365 376 388 398 113  Related-party PPAs 899 81 82 86 88 88 474  Other PPAs 3,453 247 253 229 231 233 2,260  Total PPAs $ 9,356 $ 1,008 $ 1,031 $ 1,021 $ 1,051 $ 1,044 $ 4,201  Other 1,651 895 347 157 102 19 131  MCV PPA: Consumers has a 35 ‑year PPA that began in 1990 with the MCV Partnership to purchase 1,240 MW of electricity. The MCV PPA, as amended and restated, provides for: · a capacity charge of $ 10.14 per MWh of available capacity · a fixed energy charge based on Consumers’ annual average baseload coal generating plant operating and maintenance cost, fuel inventory, and administrative and general expenses · a variable energy charge based on the MCV Partnership’s cost of production when the plant is dispatched · a $ 5 million annual contribution by the MCV Partnership to a renewable resources program · an option for Consumers to extend the MCV PPA for five years or purchase the MCV Facility at the conclusion of the MCV PPA’s term in March 2025 Capacity and energy charges under the MCV PPA were $ 305 million in 2016 , $ 282 million in 2015 , and $ 300 million in 2014 . Palisades PPA: Consumers has a PPA expiring in 2022 with Entergy to purchase virtually all of the capacity and energy produced by Palisades, up to the annual average capacity of 798 MW. For all delivered energy, the Palisades PPA has escalating capacity and variable energy charges. Total capacity and energy charges under the Palisades PPA were $ 363 million in 2016 , $ 352 million in 2015 , and $ 302 million in 2014 . In December 2016, Consumers and Entergy reached an agreement to terminate the PPA in May 2018 , subject to timely receipt of certain MPSC approvals . The payments due reflect the original terms of the PPA. For further details about Palisades, see Note 10, Leases and Palisades Financing. Other PPAs: Consumers has PPAs expiring through 2036 with various counterparties. The majority of the PPAs have capacity and energy charges for delivered energy. Capacity and energy charges under these PPAs were $348 million in 2016 , $347 million in 2015 , and $354 million in 2014 .

Financings And Capitalization

Financings And Capitalization	12 Months Ended
	Dec. 31, 2016
Financings And Capitalization	5: Financings and Capitalization Presented in the following table is CMS Energy’s long-term debt at December 31:    In Millions  Interest Rate (%) Maturity 2016 2015  CMS Energy, including Consumers  CMS Energy, parent only  Senior notes 6.550 2017 $ - $ 250  5.050 2018 - 250  8.750 2019 300 300  6.250 2020 300 300  5.050 2022 300 300  3.875 2024 250 250  3.600 2025 250 250  3.000 2026 300 -  2.950 2027 275 -  4.700 2043 250 250  4.875 2044 300 300  Total senior notes $ 2,525 $ 2,450  Term loan facility variable 1 2018 180 180  EnerBank  Certificates of deposit 1.505 2 2017 -2026 1,198 1,098  Consumers 5,661 5,409  Total principal amount outstanding $ 9,564 $ 9,137  Current amounts (864) (684)  Net unamortized discounts (15) (12)  Unamortized issuance costs (45) (41)  Total long-term debt $ 8,640 $ 8,400  1 Outstanding borrowings bear interest at an annual interest rate of LIBOR plus 0.85 percent ( 1.61 percent at December 31, 2016 ). 2 The weighted-average interest rate for EnerBank’s certificates of deposit was 1.51 percent at December 31, 2016 and 1.36 percent at December 31, 2015 . EnerBank’s primary deposit product consists of brokered certificates of deposit with varying maturities and having a face value of $ 1,000 . Presented in the following table is Consumers’ long-term debt at December 31:    In Millions  Interest Rate (%) Maturity 2016 2015  Consumers  First mortgage bonds 1 5.500 2016 $ - $ 173  5.150 2017 250 250  3.210 2017 100 100  5.650 2018 250 250  6.125 2019 350 350  6.700 2019 500 500  5.650 2020 300 300  3.770 2020 100 100  5.300 2022 250 250  2.850 2022 375 375  3.375 2023 325 325  3.190 2024 52 52  3.125 2024 250 250  3.390 2027 35 35  5.800 2035 175 175  6.170 2040 50 50  4.970 2040 50 50  4.310 2042 263 263  3.950 2043 425 425  4.100 2045 250 250  3.250 2046 450 -  4.350 2064 250 250  Total first mortgage bonds $ 5,050 $ 4,773  Securitization bonds 2.790 2 2020-2029 3 328 353  Senior notes 6.875 2018 180 180  Tax-exempt pollution control revenue bonds various 2018-2035 103 103  Total principal amount outstanding $ 5,661 $ 5,409  Current amounts (375) (198)  Net unamortized discounts (8) (5)  Unamortized issuance costs (25) (23)  Total long-term debt $ 5,253 $ 5,183  1 The weighted-average interest rate for Consumers’ first mortgage bonds was 4.57 percent at December 31, 2016 and 4.73 percent at December 31, 2015 . 2 The weighted-average interest rate for Consumers’ securitization bonds issued through its subsidiary Consumers 2014 Securitization Funding was 2.79 percent at December 31, 2016 and 2.69 percent at December 31, 2015 . 3 Principal and interest payments are made semiannually. Financings: Presented in the following table is a summary of major long-term debt transactions during the year ended December 31, 20 16 :    Principal Issue/Retirement  (In Millions) Interest Rate Date Maturity Date  Debt issuances  CMS Energy, parent only  Senior notes $ 300 3.000 % May 2016 May 2026  Senior notes 275 2.950 November 2016 February 2027  Total CMS Energy, parent only $ 575  Consumers  First mortgage bonds $ 450 3.250 % August 2016 August 2046  Total Consumers $ 450  Total CMS Energy $ 1,025  Debt retirements  CMS Energy, parent only  Senior notes $ 250 6.550 % December 2016 July 2017  Senior notes 250 5.050 December 2016 February 2018  Total CMS Energy, parent only $ 500  Consumers  First mortgage bonds $ 173 5.500 % August 2016 August 2016  Total Consumers $ 173  Total CMS Energy $ 673  First Mortgage Bonds: Consumers secures its first mortgage bonds by a mortgage and lien on substantially all of its property. Consumers’ ability to issue first mortgage bonds is restricted by certain provisions in the First Mortgage Bond Indenture and the need for regulatory approvals under federal law. Restrictive issuance provisions in the First Mortgage Bond Indenture include achieving a two-times interest coverage ratio and having sufficient unfunded net property additions. Term Loan: In April 2016, the maturity date of CMS Energy’s $180 million term loan was extended by one year, through April 2018 . Regulatory Authorization for Financings: Consumers is required to maintain FERC authorization for financings. In June 2016, Consumers received authorization from FERC to have outstanding, at any one time, up to $ 800 million of secured and unsecured short-term securities for general corporate purposes. At December 31, 20 16 , Consumers had entered into short-term borrowing programs allowing it to issue up to $800 million in short-term securities; $398 million of securities were outstanding under these programs. FERC has also authorized Consumers to issue and sell up to $ 1.8 billion of secured and unsecured long-term securities for general corporate purposes. The remaining availability was $ 1.3 b illion at December 31, 20 16 . The authorizations were effective July 1, 2016 and terminate June 30, 2018. Any long-term issuances during the authorization period are exempt from FERC’s competitive bidding and negotiated placement requirements. Securitization Bonds: Certain regulatory assets held by Consumers’ subsidiary, Consumers 2014 Securitization Funding, collateralize Consumers’ securitization bonds. The bondholders have no recourse to Consumers’ assets except for those held by the subsidiary that issued the bonds. Consumers collects securitization surcharges to cover the principal and interest on the bonds as well as certain other qualified costs. The surcharges collected are remitted to a trustee and are not available to creditors of Consumers or creditors of Consumers’ affiliates other than the subsidiary that issued the bonds. Debt Maturities: At December 31, 20 16 , the aggregate annual contractual maturities for long-term debt for the next five years were:    In Millions  2017 2018 2019 2020 2021  CMS Energy, including Consumers  Long-term debt $ 864 $ 975 $ 1,326 $ 850 $ 103  Consumers  Long-term debt $ 375 $ 523 $ 876 $ 426 $ 27  Revolving Credit Facilities: The following secured revolving credit facilities with banks were available at December 31, 20 16 :    In Millions  Amount of Amount Letters of Credit Amount  Expiration Date Facility Borrowed Outstanding Available  CMS Energy, parent only  May 27, 2021 1,3 $ 550 $ - $ 1 $ 549  Consumers  May 27, 2021 1,4 $ 650 $ - $ 7 $ 643  November 23, 2018 2,4 250 - - 250  May 9, 2018 4 30 - 30 -  1 In May 2016, the expiration date of this revolving credit agreement was extended from 2020 to 2021. 2 In November 2016, the expiration date of this revolving credit agreement was extended from 2017 to 2018. 3 During the year ended December 31, 2016, CMS Energy’s average borrowings totaled $ 3 million with a weighted-average interest rate of 1.68 percent. Obligations under this facility are secured by Consumers common stock. 4 Obligations under this facility are secured by first mortgage bonds of Consumers.  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’ $650 million revolving credit facility and may have an aggregate principal amount outstanding of up to $500 million. While the amount of outstanding commercial paper does not reduce the revolver’s available capacity, Consumers does not intend to issue commercial paper in an amount exceeding the available revolver capacity. At December 31, 2016 , $ 398 million of commercial paper notes with a weighted-average annual interest rate of 1. 14 percent w ere outstanding under this program and are recorded as current notes payable on the consolidated balance sheets of CMS Energy and Consumers. Dividend Restrictions: At December 31, 20 16 , payment of dividends by CMS Energy on its common stock was limited to $ 4.3 billion under provisions of the Michigan Business Corporation Act of 1972 . Under the provisions of its articles of incorporation, at December 31, 20 16 , Consumers had $ 1.0 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 year ended December 31, 20 16 , Consumers paid $ 499 million in dividends on its common stock to CMS Energy. Capitalization: The authorized capital stock of CMS Energy consists of: · 350 million shares of CMS Energy Common Stock, par value $ 0.01 per share · 10 million shares of CMS Energy Preferred Stock, par value $ 0.01 per share Issuance of Common Stock: In April 2015, 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 Average Proceeds  Shares Issued Price per Share (In Millions)  2015 888,610 $ 33.76 $ 30  2016 1,449,171 41.40 60  Total 2,337,781 $ 38.50 $ 90  Preferred Stock of Subsidiary: Presented in the following table are details about Consumers’ preferred stock outstanding:    Optional Number of Balance  Redemption Shares Outstanding  Series Price Outstanding (In Millions)  December 31 2016 2015  Cumulative, $100 par value, authorized 7,500,000 shares, with no mandatory redemption $ 4.50 $ 110.00 373,148 $ 37 $ 37 1 
Consumers Energy Company [Member]
Financings And Capitalization	5: Financings and Capitalization Presented in the following table is CMS Energy’s long-term debt at December 31:    In Millions  Interest Rate (%) Maturity 2016 2015  CMS Energy, including Consumers  CMS Energy, parent only  Senior notes 6.550 2017 $ - $ 250  5.050 2018 - 250  8.750 2019 300 300  6.250 2020 300 300  5.050 2022 300 300  3.875 2024 250 250  3.600 2025 250 250  3.000 2026 300 -  2.950 2027 275 -  4.700 2043 250 250  4.875 2044 300 300  Total senior notes $ 2,525 $ 2,450  Term loan facility variable 1 2018 180 180  EnerBank  Certificates of deposit 1.505 2 2017 -2026 1,198 1,098  Consumers 5,661 5,409  Total principal amount outstanding $ 9,564 $ 9,137  Current amounts (864) (684)  Net unamortized discounts (15) (12)  Unamortized issuance costs (45) (41)  Total long-term debt $ 8,640 $ 8,400  1 Outstanding borrowings bear interest at an annual interest rate of LIBOR plus 0.85 percent ( 1.61 percent at December 31, 2016 ). 2 The weighted-average interest rate for EnerBank’s certificates of deposit was 1.51 percent at December 31, 2016 and 1.36 percent at December 31, 2015 . EnerBank’s primary deposit product consists of brokered certificates of deposit with varying maturities and having a face value of $ 1,000 . Presented in the following table is Consumers’ long-term debt at December 31:    In Millions  Interest Rate (%) Maturity 2016 2015  Consumers  First mortgage bonds 1 5.500 2016 $ - $ 173  5.150 2017 250 250  3.210 2017 100 100  5.650 2018 250 250  6.125 2019 350 350  6.700 2019 500 500  5.650 2020 300 300  3.770 2020 100 100  5.300 2022 250 250  2.850 2022 375 375  3.375 2023 325 325  3.190 2024 52 52  3.125 2024 250 250  3.390 2027 35 35  5.800 2035 175 175  6.170 2040 50 50  4.970 2040 50 50  4.310 2042 263 263  3.950 2043 425 425  4.100 2045 250 250  3.250 2046 450 -  4.350 2064 250 250  Total first mortgage bonds $ 5,050 $ 4,773  Securitization bonds 2.790 2 2020-2029 3 328 353  Senior notes 6.875 2018 180 180  Tax-exempt pollution control revenue bonds various 2018-2035 103 103  Total principal amount outstanding $ 5,661 $ 5,409  Current amounts (375) (198)  Net unamortized discounts (8) (5)  Unamortized issuance costs (25) (23)  Total long-term debt $ 5,253 $ 5,183  1 The weighted-average interest rate for Consumers’ first mortgage bonds was 4.57 percent at December 31, 2016 and 4.73 percent at December 31, 2015 . 2 The weighted-average interest rate for Consumers’ securitization bonds issued through its subsidiary Consumers 2014 Securitization Funding was 2.79 percent at December 31, 2016 and 2.69 percent at December 31, 2015 . 3 Principal and interest payments are made semiannually. Financings: Presented in the following table is a summary of major long-term debt transactions during the year ended December 31, 20 16 :    Principal Issue/Retirement  (In Millions) Interest Rate Date Maturity Date  Debt issuances  CMS Energy, parent only  Senior notes $ 300 3.000 % May 2016 May 2026  Senior notes 275 2.950 November 2016 February 2027  Total CMS Energy, parent only $ 575  Consumers  First mortgage bonds $ 450 3.250 % August 2016 August 2046  Total Consumers $ 450  Total CMS Energy $ 1,025  Debt retirements  CMS Energy, parent only  Senior notes $ 250 6.550 % December 2016 July 2017  Senior notes 250 5.050 December 2016 February 2018  Total CMS Energy, parent only $ 500  Consumers  First mortgage bonds $ 173 5.500 % August 2016 August 2016  Total Consumers $ 173  Total CMS Energy $ 673  First Mortgage Bonds: Consumers secures its first mortgage bonds by a mortgage and lien on substantially all of its property. Consumers’ ability to issue first mortgage bonds is restricted by certain provisions in the First Mortgage Bond Indenture and the need for regulatory approvals under federal law. Restrictive issuance provisions in the First Mortgage Bond Indenture include achieving a two-times interest coverage ratio and having sufficient unfunded net property additions. Term Loan: In April 2016, the maturity date of CMS Energy’s $180 million term loan was extended by one year, through April 2018 . Regulatory Authorization for Financings: Consumers is required to maintain FERC authorization for financings. In June 2016, Consumers received authorization from FERC to have outstanding, at any one time, up to $ 800 million of secured and unsecured short-term securities for general corporate purposes. At December 31, 20 16 , Consumers had entered into short-term borrowing programs allowing it to issue up to $800 million in short-term securities; $398 million of securities were outstanding under these programs. FERC has also authorized Consumers to issue and sell up to $ 1.8 billion of secured and unsecured long-term securities for general corporate purposes. The remaining availability was $ 1.3 b illion at December 31, 20 16 . The authorizations were effective July 1, 2016 and terminate June 30, 2018. Any long-term issuances during the authorization period are exempt from FERC’s competitive bidding and negotiated placement requirements. Securitization Bonds: Certain regulatory assets held by Consumers’ subsidiary, Consumers 2014 Securitization Funding, collateralize Consumers’ securitization bonds. The bondholders have no recourse to Consumers’ assets except for those held by the subsidiary that issued the bonds. Consumers collects securitization surcharges to cover the principal and interest on the bonds as well as certain other qualified costs. The surcharges collected are remitted to a trustee and are not available to creditors of Consumers or creditors of Consumers’ affiliates other than the subsidiary that issued the bonds. Debt Maturities: At December 31, 20 16 , the aggregate annual contractual maturities for long-term debt for the next five years were:    In Millions  2017 2018 2019 2020 2021  CMS Energy, including Consumers  Long-term debt $ 864 $ 975 $ 1,326 $ 850 $ 103  Consumers  Long-term debt $ 375 $ 523 $ 876 $ 426 $ 27  Revolving Credit Facilities: The following secured revolving credit facilities with banks were available at December 31, 20 16 :    In Millions  Amount of Amount Letters of Credit Amount  Expiration Date Facility Borrowed Outstanding Available  CMS Energy, parent only  May 27, 2021 1,3 $ 550 $ - $ 1 $ 549  Consumers  May 27, 2021 1,4 $ 650 $ - $ 7 $ 643  November 23, 2018 2,4 250 - - 250  May 9, 2018 4 30 - 30 -  1 In May 2016, the expiration date of this revolving credit agreement was extended from 2020 to 2021. 2 In November 2016, the expiration date of this revolving credit agreement was extended from 2017 to 2018. 3 During the year ended December 31, 2016, CMS Energy’s average borrowings totaled $ 3 million with a weighted-average interest rate of 1.68 percent. Obligations under this facility are secured by Consumers common stock. 4 Obligations under this facility are secured by first mortgage bonds of Consumers.  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’ $650 million revolving credit facility and may have an aggregate principal amount outstanding of up to $500 million. While the amount of outstanding commercial paper does not reduce the revolver’s available capacity, Consumers does not intend to issue commercial paper in an amount exceeding the available revolver capacity. At December 31, 2016 , $ 398 million of commercial paper notes with a weighted-average annual interest rate of 1. 14 percent w ere outstanding under this program and are recorded as current notes payable on the consolidated balance sheets of CMS Energy and Consumers. Dividend Restrictions: At December 31, 20 16 , payment of dividends by CMS Energy on its common stock was limited to $ 4.3 billion under provisions of the Michigan Business Corporation Act of 1972 . Under the provisions of its articles of incorporation, at December 31, 20 16 , Consumers had $ 1.0 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 year ended December 31, 20 16 , Consumers paid $ 499 million in dividends on its common stock to CMS Energy. Capitalization: The authorized capital stock of CMS Energy consists of: · 350 million shares of CMS Energy Common Stock, par value $ 0.01 per share · 10 million shares of CMS Energy Preferred Stock, par value $ 0.01 per share Issuance of Common Stock: In April 2015, 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 Average Proceeds  Shares Issued Price per Share (In Millions)  2015 888,610 $ 33.76 $ 30  2016 1,449,171 41.40 60  Total 2,337,781 $ 38.50 $ 90  Preferred Stock of Subsidiary: Presented in the following table are details about Consumers’ preferred stock outstanding:    Optional Number of Balance  Redemption Shares Outstanding  Series Price Outstanding (In Millions)  December 31 2016 2015  Cumulative, $100 par value, authorized 7,500,000 shares, with no mandatory redemption $ 4.50 $ 110.00 373,148 $ 37 $ 37 1 

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Measurements	6: F air V alue M easurements 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  December 31 2016 2015 2016 2015  Assets 1  Cash equivalents $ 44 $ 158 $ - $ -  Restricted cash equivalents 19 19 19 19  CMS Energy common stock - - 33 29  Nonqualified deferred compensation plan assets 12 10 8 7  DB SERP  Cash equivalents 3 2 2 2  Mutual funds 141 146 102 104  Derivative instruments  Commodity contracts 1 1 1 1  Total $ 220 $ 336 $ 165 $ 162  Liabilities 1  Nonqualified deferred compensation plan liabilities $ 12 $ 10 $ 8 $ 7  Total $ 12 $ 10 $ 8 $ 7  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 NAVs. 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 NAVs. 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 7, 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 derivatives classified as Level 3 are FTRs held by Consumers. Due to the lack of quoted pricing information, Consumers determines the fair value of its FTRs based on Consumers’ average historical settlements. Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Level 3 Inputs Presented in the following table are reconciliations of changes in the fair values of Level 3 assets and liabilities at CMS Energy and Consumers :    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Balance at beginning of period $ 1 $ 1 $ 4  Total gains (losses) included in earnings 1 1 (1) -  Total gains (losses) offset through regulatory accounting (2) 2 (15)  Purchases 2 1 (1)  Settlements (1) (2) 13  Balance at end of period $ 1 $ 1 $ 1  Consumers  Balance at beginning of period $ 1 $ 1 $ 4  Total gains included in earnings 1 1 - -  Total gains (losses) offset through regulatory accounting (2) 2 (15)  Purchases 2 - (1)  Settlements (1) (2) 13  Balance at end of period $ 1 $ 1 $ 1  1 CMS Energy and Consumers record realized gains and losses for Level 3 recurring fair value measurements in earnings as a component of maintenance and other operating expenses or purchased and interchange power on their consolidated statements of income.
Consumers Energy Company [Member]
Fair Value Measurements	6: F air V alue M easurements 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  December 31 2016 2015 2016 2015  Assets 1  Cash equivalents $ 44 $ 158 $ - $ -  Restricted cash equivalents 19 19 19 19  CMS Energy common stock - - 33 29  Nonqualified deferred compensation plan assets 12 10 8 7  DB SERP  Cash equivalents 3 2 2 2  Mutual funds 141 146 102 104  Derivative instruments  Commodity contracts 1 1 1 1  Total $ 220 $ 336 $ 165 $ 162  Liabilities 1  Nonqualified deferred compensation plan liabilities $ 12 $ 10 $ 8 $ 7  Total $ 12 $ 10 $ 8 $ 7  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 NAVs. 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 NAVs. 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 7, 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 derivatives classified as Level 3 are FTRs held by Consumers. Due to the lack of quoted pricing information, Consumers determines the fair value of its FTRs based on Consumers’ average historical settlements. Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Level 3 Inputs Presented in the following table are reconciliations of changes in the fair values of Level 3 assets and liabilities at CMS Energy and Consumers :    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Balance at beginning of period $ 1 $ 1 $ 4  Total gains (losses) included in earnings 1 1 (1) -  Total gains (losses) offset through regulatory accounting (2) 2 (15)  Purchases 2 1 (1)  Settlements (1) (2) 13  Balance at end of period $ 1 $ 1 $ 1  Consumers  Balance at beginning of period $ 1 $ 1 $ 4  Total gains included in earnings 1 1 - -  Total gains (losses) offset through regulatory accounting (2) 2 (15)  Purchases 2 - (1)  Settlements (1) (2) 13  Balance at end of period $ 1 $ 1 $ 1  1 CMS Energy and Consumers record realized gains and losses for Level 3 recurring fair value measurements in earnings as a component of maintenance and other operating expenses or purchased and interchange power on their consolidated statements of income.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2016
Financial Instruments	7: F inancial I nstruments 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 6, Fair Value Measurements.    In Millions  December 31, 2016 December 31, 2015  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 $ - $ - $ - $ - $ -  Notes receivable 2 1,326 1,415 - - 1,415 1,161 1,228 - - 1,228  Securities held to maturity 13 13 - 13 - 11 11 - 11 -  Liabilities  Long-term debt 3 9,504 9,953 - 8,990 963 9,084 9,599 - 8,648 951  Long-term payables 4 17 17 - - 17 14 14 - - 14  Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ - $ - $ - $ - $ -  Notes receivable 5 45 45 - - 45 - - - - -  Liabilities  Long-term debt 6 5,628 5,903 - 4,940 963 5,381 5,684 - 4,733 951  1 Includes current accounts receivable of $12 million at December 31, 2016 . 2 Includes current portion of notes receivable of $ 219 million at December 31, 2016 and $ 144 million at December 31, 2015 . 3 Includes current portion of long-term debt of $ 864 million at December 31, 2016 and $ 684 million at December 31, 2015 . 4 Includes current portion of long-term payables of $ 1 million at December 31, 2016 and 2015 . 5 Includes current portion of notes receivable of $29 million at Decemb er 31, 2 016 . 6 Includes current portion of long-term debt of $ 375 million at December 31, 2016 and $ 198 million at December 31, 2015 . At CMS Energy, n otes 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 December 31, 2016 and 2015 , 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  December 31, 2016 December 31, 2015  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 $ 141 $ - $ - $ 141 $ 152 $ - $ 6 $ 146  Held to maturity  Debt securities 13 - - 13 11 - - 11  Consumers  Available for sale  DB SERP  Mutual funds $ 102 $ - $ - $ 102 $ 108 $ - $ 4 $ 104  CMS Energy common stock 4 29 - 33 4 25 - 29  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. CMS Energy and Consumers determined that the unrealized losses on the mutual funds in the DB SERP were other than temporary at December 31, 2016. Accordingly, CMS Energy reclassified unrealized losses of $5 million ( $3 million, net of tax) from AOCI to other expense on the consolidated statements of income and established a new cost basis of $141 million for these investments, which was equal to fair value at December 31, 2016. Consumers reclassified net unrealized losses of $4 million ( $2 million, net of tax) from AOCI to other expense on the consolidated statements of income and established a new cost basis of $102 million for these investments, which was equal to fair value at December 31, 2016. Presented in the following table is a summary of the sales activity for CMS Energy’s and Consumers’ investment securities:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Proceeds from sales of investment securities $ 6 $ 3 $ 8  Consumers  Proceeds from sales of investment securities $ 4 $ 2 $ 6  The sales proceeds for all periods represent sales of investments that were held within the DB SERP and classified as available for sale. Realized gains and losses on the sales were insignificant for CMS Energy and Consumers during each period. Consumers recognized a gain of $9 million in 2015 from transferring shares of CMS Energy common stock to a related charitable foundation. The gains reflected the excess of fair value over cost of the stock donated and were recorded in other income on Consumers’ consolidated statements of income. The gains were eliminated on CMS Energy’s consolidated statements of income. Consumers did not transfer shares in 2016 or 2014.
Consumers Energy Company [Member]
Financial Instruments	7: F inancial I nstruments 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 6, Fair Value Measurements.    In Millions  December 31, 2016 December 31, 2015  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 $ - $ - $ - $ - $ -  Notes receivable 2 1,326 1,415 - - 1,415 1,161 1,228 - - 1,228  Securities held to maturity 13 13 - 13 - 11 11 - 11 -  Liabilities  Long-term debt 3 9,504 9,953 - 8,990 963 9,084 9,599 - 8,648 951  Long-term payables 4 17 17 - - 17 14 14 - - 14  Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ - $ - $ - $ - $ -  Notes receivable 5 45 45 - - 45 - - - - -  Liabilities  Long-term debt 6 5,628 5,903 - 4,940 963 5,381 5,684 - 4,733 951  1 Includes current accounts receivable of $12 million at December 31, 2016 . 2 Includes current portion of notes receivable of $ 219 million at December 31, 2016 and $ 144 million at December 31, 2015 . 3 Includes current portion of long-term debt of $ 864 million at December 31, 2016 and $ 684 million at December 31, 2015 . 4 Includes current portion of long-term payables of $ 1 million at December 31, 2016 and 2015 . 5 Includes current portion of notes receivable of $29 million at Decemb er 31, 2 016 . 6 Includes current portion of long-term debt of $ 375 million at December 31, 2016 and $ 198 million at December 31, 2015 . At CMS Energy, n otes 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 December 31, 2016 and 2015 , 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  December 31, 2016 December 31, 2015  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 $ 141 $ - $ - $ 141 $ 152 $ - $ 6 $ 146  Held to maturity  Debt securities 13 - - 13 11 - - 11  Consumers  Available for sale  DB SERP  Mutual funds $ 102 $ - $ - $ 102 $ 108 $ - $ 4 $ 104  CMS Energy common stock 4 29 - 33 4 25 - 29  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. CMS Energy and Consumers determined that the unrealized losses on the mutual funds in the DB SERP were other than temporary at December 31, 2016. Accordingly, CMS Energy reclassified unrealized losses of $5 million ( $3 million, net of tax) from AOCI to other expense on the consolidated statements of income and established a new cost basis of $141 million for these investments, which was equal to fair value at December 31, 2016. Consumers reclassified net unrealized losses of $4 million ( $2 million, net of tax) from AOCI to other expense on the consolidated statements of income and established a new cost basis of $102 million for these investments, which was equal to fair value at December 31, 2016. Presented in the following table is a summary of the sales activity for CMS Energy’s and Consumers’ investment securities:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Proceeds from sales of investment securities $ 6 $ 3 $ 8  Consumers  Proceeds from sales of investment securities $ 4 $ 2 $ 6  The sales proceeds for all periods represent sales of investments that were held within the DB SERP and classified as available for sale. Realized gains and losses on the sales were insignificant for CMS Energy and Consumers during each period. Consumers recognized a gain of $9 million in 2015 from transferring shares of CMS Energy common stock to a related charitable foundation. The gains reflected the excess of fair value over cost of the stock donated and were recorded in other income on Consumers’ consolidated statements of income. The gains were eliminated on CMS Energy’s consolidated statements of income. Consumers did not transfer shares in 2016 or 2014.

Notes Receivable

Notes Receivable	12 Months Ended
	Dec. 31, 2016
Notes Receivable	8: N otes R eceivable Presented in the following table are details of CMS Energy’s and Consumers’ current and non ‑current notes receivable:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  Current  EnerBank notes receivable, net of allowance for loan losses $ 151 $ 128  EnerBank notes receivable held for sale 39 16  State of Michigan tax settlement 29 -  Non-current  EnerBank notes receivable 1,088 1,017  State of Michigan tax settlement 19 -  Total notes receivable $ 1,326 $ 1,161  Consumers  Current  State of Michigan tax settlement $ 29 $ -  Non-current  State of Michigan tax settlement 16 -  Total notes receivable $ 45 $ -  EnerBank notes receivable are unsecured consumer installment loans for financing home improvements. EnerBank records its notes receivable at cost, less an a llowance for loan losses. At December 31, 2016 , $ 39 million of notes receivable were 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 . Unearned income associated with loan fees was $84 million at December 31, 2016 and $82 million at December 31, 2015. Unearned income associated with loan fees for notes receivable held for sale was $8 million at December 31, 2016 and $3 million at December 31, 2015 . 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. Presented in the following table are the changes in the allowance for loan losses:    In Millions  Years Ended December 31 2016 2015  Balance at beginning of period $ 9 $ 8  Charge-offs (14) (8)  Recoveries 2 1  Provision for loan losses 19 8  Balance at end of period $ 16 $ 9  Loans that are 30 days or more past due are considered delinquent. The balance of EnerBank’s delinquent consumer loans was $ 11 million at December 31, 2016 and $ 8 million at December 31, 2015 . At December 31, 2016 and 2015 , $ 1 million of EnerBank’s loans had been modified as troubled debt restructurings.
Consumers Energy Company [Member]
Notes Receivable	8: N otes R eceivable Presented in the following table are details of CMS Energy’s and Consumers’ current and non ‑current notes receivable:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  Current  EnerBank notes receivable, net of allowance for loan losses $ 151 $ 128  EnerBank notes receivable held for sale 39 16  State of Michigan tax settlement 29 -  Non-current  EnerBank notes receivable 1,088 1,017  State of Michigan tax settlement 19 -  Total notes receivable $ 1,326 $ 1,161  Consumers  Current  State of Michigan tax settlement $ 29 $ -  Non-current  State of Michigan tax settlement 16 -  Total notes receivable $ 45 $ -  EnerBank notes receivable are unsecured consumer installment loans for financing home improvements. EnerBank records its notes receivable at cost, less an a llowance for loan losses. At December 31, 2016 , $ 39 million of notes receivable were 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 . Unearned income associated with loan fees was $84 million at December 31, 2016 and $82 million at December 31, 2015. Unearned income associated with loan fees for notes receivable held for sale was $8 million at December 31, 2016 and $3 million at December 31, 2015 . 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. Presented in the following table are the changes in the allowance for loan losses:    In Millions  Years Ended December 31 2016 2015  Balance at beginning of period $ 9 $ 8  Charge-offs (14) (8)  Recoveries 2 1  Provision for loan losses 19 8  Balance at end of period $ 16 $ 9  Loans that are 30 days or more past due are considered delinquent. The balance of EnerBank’s delinquent consumer loans was $ 11 million at December 31, 2016 and $ 8 million at December 31, 2015 . At December 31, 2016 and 2015 , $ 1 million of EnerBank’s loans had been modified as troubled debt restructurings.

Plant, Property, and Equipment

Plant, Property, and Equipment	12 Months Ended
	Dec. 31, 2016
Plant, Property, and Equipment	9: P lant , P roperty , and E quipment Presented in the following table are details of CMS Energy’s and Consumers’ plant, property, and equipment:    In Millions  December 31 Estimated Depreciable Life in Years 2016 2015  CMS Energy, including Consumers  Plant, property, and equipment, gross  Consumers 5 - 125 $ 20,838 $ 18,797  Enterprises  Independent power production 3 - 30 141 95  Other 3 - 40 16 25  Other 1 - 7 15 26  Plant, property, and equipment, gross $ 21,010 $ 18,943  Construction work in progress 761 1,509  Less accumulated depreciation and amortization (6,056) (5,747)  Total plant, property, and equipment 1 $ 15,715 $ 14,705  Consumers  Plant, property, and equipment, gross  Electric  Generation 22 - 125 $ 5,900 $ 4,925  Distribution 20 - 75 7,149 6,809  Transmission 46 - 75 59 -  Other 5 - 50 1,137 1,039  Assets under capital leases and financing obligation 295 286  Gas  Distribution 28 - 80 3,806 3,497  Transmission 17 - 75 1,124 981  Underground storage facilities 2 29 - 65 630 601  Other 5 - 50 708 630  Capital leases 15 14  Other non-utility property 8 - 51 15 15  Plant, property, and equipment, gross $ 20,838 $ 18,797  Construction work in progress 759 1,467  Less accumulated depreciation and amortization (5,994) (5,676)  Total plant, property, and equipment 1 $ 15,603 $ 14,588  1 For the year ended December 31, 20 16 , Consumers’ plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 20 15 , Consumers’ plant additions were $ 1.4 billion and plant retirements were $ 187 million. 2 Underground storage includes base natural gas of $26 million at December 31, 20 16 and 2015 . Base natural gas is not subject to depreciation. Capitalization : CMS Energy and Consumers record plant, property, and equipment at original cost when placed into service. The cost includes labor, material, applicable taxes, overhead such as pension and other benefits, and AFUDC, if applicable. Consumers’ plant, property, and equipment is generally recoverable through its general rate making process. With the exception of utility property for which the remaining book value has been securitized, mothballed utility property stays in rate base and continues to be depreciated at the same rate as before the mothball period. When utility property is retired or otherwise disposed of in the ordinary course of business, Consumers records the original cost to accumulated depreciation, along with associated cost of removal, net of salvage. CMS Energy and Consumers recognize gains or losses on the retirement or disposal of non ‑regulated assets in income. Consumers records cost of removal collected from customers, but not spent, as a regulatory liability. Software : CMS Energy and Consumers capitalize the costs to purchase and develop internal-use computer software. These costs are expensed evenly over the estimated useful life of the internal-use computer software. If computer software is integral to computer hardware, then its cost is capitalized and depreciated with the hardware. AFUDC : Consumers capitalizes AFUDC on regulated major construction projects, except pollution control facilities on its fossil-fuel-fired power plants. AFUDC represents the estimated cost of debt and authorized return-on-equity funds used to finance construction additions. Consumers records the offsetting credit as a reduction of interest for the amount representing the borrowed funds component and as other income for the equity funds component on the consolidated statements of income. When construction is completed and the property is placed in service, Consumers depreciates and recovers the capitalized AFUDC from customers over the life of the related asset . Presented in the following table are Consumers’ composite AFUDC capitalization rates:    Years Ended December 31 2016 2015 2014  AFUDC capitalization rate 7.0 % 7.1 % 7.2 %  Electric Transmission: In October 2015, Consumers became registered under NERC standards as a transmission owner, transmission planner, and transmission operator. Consumers had previously received approval from the MPSC in 2014 and from FERC in 2015 to reclassify $34 million of net plant assets from distribution to transmission. In March 2016, Consumers received FERC approval to begin collecting transmission revenues under MISO’s transmission tariff effective April 2016. Consumers completed the reclassification of plant assets from distribution to transmission in April 2016. Electric Plant Purchase: In December 2015, Consumers completed the purchase of a 540 ‑MW natural gas-fueled electric generating plant located in Jackson, Michigan for $155 million from AlphaGen Power LLC and DPC Juniper, LLC, affiliates of JPMorgan Chase & Co. Consumers purchased the plant to help address its future capacity requirements. Consumers accounted for the purchase as a business combination and prepared a valuation analysis of the assets acquired and liabilities assumed to determine their fair values. The cash consideration of $155 million was allocated based on the underlying fair values of the assets acquired, which were primarily plant, property, and equipment, and the liabilities assumed. No goodwill was recorded as a result of this purchase. The pro forma results of operations have not been presented, as the effects of the acquisition would not have been material to CMS Energy’s or Consumers’ consolidated results of operations in 2015. Assets Under Capital Leases and Financing Obligation : Presented in the following table are further details about changes in Consumers’ assets under capital leases and financing obligation :    In Millions  Years Ended December 31 2016 2015  Consumers  Balance at beginning of period $ 300 $ 295  Additions 13 17  Net retirements and other adjustments (3) (12)  Balance at end of period $ 310 $ 300  Assets under capital leases and financing obligation are presented as gross amounts. Accumulated amortization of assets under capital leases and financing obligation was $172 million at December 31, 2016 and $ 152 million at December 31, 2015 for Consumers. Depreciation and Amortization : Presented in the following table are further details about CMS Energy’s and Consumers’ accumulated depreciation and amortization:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  Utility plant assets $ 5,993 $ 5,674  Non-utility plant assets 63 73  Consumers  Utility plant assets $ 5,993 $ 5,674  Non-utility plant assets 1 2  Consumers depreciates utility property on an asset-group basis, in which it applies a single MPSC-approved depreciation rate to the gross investment in a particular class of property within the electric and gas segments. Consumers performs depreciation studies periodically to determine appropriate group lives. Presented in the following table are the composite depreciation rates for Consumers’ segment properties:    Years Ended December 31 2016 2015 2014  Electric utility property 3.9 % 3.5 % 3.5 %  Gas utility property 2.9 2.8 2.8  Other property 9.8 8.7 7.7  CMS Energy and Consumers record property repairs and minor property replacement as maintenance expense. CMS Energy and Consumers record planned major maintenance activities as operating expense unless the cost represents the acquisition of additional long-lived assets or the replacement of an existing long-lived asset. Pre sented in the following table are the components of CMS Energy’s and Consumers’ depreciation and amortization expe nse :    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Depreciation expense – plant, property, and equipment $ 687 $ 591 $ 551  Amortization expense  Software 96 70 50  Other intangible assets 3 4 4  Securitized regulatory assets 25 83 75  Other regulatory assets - 2 5  Total depreciation and amortization expense $ 811 $ 750 $ 685  Consumers  Depreciation expense – plant, property, and equipment $ 680 $ 586 $ 546  Amortization expense  Software 95 69 49  Other intangible assets 3 4 3  Securitized regulatory assets 25 83 75  Other regulatory assets - 2 5  Total depreciation and amortization expense $ 803 $ 744 $ 678  Presented in the following table is CMS Energy’s and Consumers’ estimated amortization expense on intangible assets for each of the next five years:    In Millions  2017 2018 2019 2020 2021  CMS Energy, including Consumers  Intangible asset amortization expense $ 115 $ 120 $ 112 $ 95 $ 77  Consumers  Intangible assets amortization expense $ 114 $ 119 $ 111 $ 94 $ 77  Intangible Assets: Included in net plant, property, and equipment are intangible assets. Presented in the following table are details about CMS Energy’s and Consumers’ intangible assets:    In Millions  December 31, 2016 December 31, 2015  Description Amortization Life in Years Gross Cost 1 Accumulated Amortization Gross Cost 1 Accumulated Amortization  CMS Energy, including Consumers  Software development 1 - 15 $ 853 $ 367 $ 734 $ 294  Rights of way 50 - 75 155 48 153 46  Franchises and consents 5 - 30 15 8 15 8  Leasehold improvements various 2 7 6 7 5  Other intangibles various 22 15 21 15  Total $ 1,052 $ 444 $ 930 $ 368  Consumers  Software development 3 - 15 $ 845 $ 363 $ 729 $ 291  Rights of way 50 - 75 155 48 153 46  Franchises and consents 5 - 30 15 8 15 8  Leasehold improvements various 2 7 6 7 5  Other intangibles various 21 15 21 15  Total $ 1,043 $ 440 $ 925 $ 365  1 For the year ended December 31, 20 16 , Consumers’ intangible asset additions were $141 million and intangible asset retirements were $23 million. For the year ended December 31, 20 15 , Consumers’ intangible asset additions were $ 140 million and there were no retirements . 2 Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended. Jointly Owned Regulated Utility Facilities Presented in the following table are Consumers’ investments in jointly owned regulated utility facilities at December 31, 20 16 :    In Millions, Except Ownership Share  J.H. Campbell Unit 3 Ludington Distribution  Ownership share 93.3 % 51.0 % various  Utility plant in service $ 1,648 $ 291 $ 206  Accumulated depreciation (529) (150) (63)  Construction work in progress 13 157 7  Net investment $ 1,132 $ 298 $ 150  Consumers includes its share of the direct expenses of the jointly owned plants in operating expenses. Consumers shares operation, maintenance, and other expenses of these jointly owned utility facilities in proportion to each participant’s undivided ownership interest. Consumers is required to provide only its share of financing for the jointly owned utility facilities.
Consumers Energy Company [Member]
Plant, Property, and Equipment	9: P lant , P roperty , and E quipment Presented in the following table are details of CMS Energy’s and Consumers’ plant, property, and equipment:    In Millions  December 31 Estimated Depreciable Life in Years 2016 2015  CMS Energy, including Consumers  Plant, property, and equipment, gross  Consumers 5 - 125 $ 20,838 $ 18,797  Enterprises  Independent power production 3 - 30 141 95  Other 3 - 40 16 25  Other 1 - 7 15 26  Plant, property, and equipment, gross $ 21,010 $ 18,943  Construction work in progress 761 1,509  Less accumulated depreciation and amortization (6,056) (5,747)  Total plant, property, and equipment 1 $ 15,715 $ 14,705  Consumers  Plant, property, and equipment, gross  Electric  Generation 22 - 125 $ 5,900 $ 4,925  Distribution 20 - 75 7,149 6,809  Transmission 46 - 75 59 -  Other 5 - 50 1,137 1,039  Assets under capital leases and financing obligation 295 286  Gas  Distribution 28 - 80 3,806 3,497  Transmission 17 - 75 1,124 981  Underground storage facilities 2 29 - 65 630 601  Other 5 - 50 708 630  Capital leases 15 14  Other non-utility property 8 - 51 15 15  Plant, property, and equipment, gross $ 20,838 $ 18,797  Construction work in progress 759 1,467  Less accumulated depreciation and amortization (5,994) (5,676)  Total plant, property, and equipment 1 $ 15,603 $ 14,588  1 For the year ended December 31, 20 16 , Consumers’ plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 20 15 , Consumers’ plant additions were $ 1.4 billion and plant retirements were $ 187 million. 2 Underground storage includes base natural gas of $26 million at December 31, 20 16 and 2015 . Base natural gas is not subject to depreciation. Capitalization : CMS Energy and Consumers record plant, property, and equipment at original cost when placed into service. The cost includes labor, material, applicable taxes, overhead such as pension and other benefits, and AFUDC, if applicable. Consumers’ plant, property, and equipment is generally recoverable through its general rate making process. With the exception of utility property for which the remaining book value has been securitized, mothballed utility property stays in rate base and continues to be depreciated at the same rate as before the mothball period. When utility property is retired or otherwise disposed of in the ordinary course of business, Consumers records the original cost to accumulated depreciation, along with associated cost of removal, net of salvage. CMS Energy and Consumers recognize gains or losses on the retirement or disposal of non ‑regulated assets in income. Consumers records cost of removal collected from customers, but not spent, as a regulatory liability. Software : CMS Energy and Consumers capitalize the costs to purchase and develop internal-use computer software. These costs are expensed evenly over the estimated useful life of the internal-use computer software. If computer software is integral to computer hardware, then its cost is capitalized and depreciated with the hardware. AFUDC : Consumers capitalizes AFUDC on regulated major construction projects, except pollution control facilities on its fossil-fuel-fired power plants. AFUDC represents the estimated cost of debt and authorized return-on-equity funds used to finance construction additions. Consumers records the offsetting credit as a reduction of interest for the amount representing the borrowed funds component and as other income for the equity funds component on the consolidated statements of income. When construction is completed and the property is placed in service, Consumers depreciates and recovers the capitalized AFUDC from customers over the life of the related asset . Presented in the following table are Consumers’ composite AFUDC capitalization rates:    Years Ended December 31 2016 2015 2014  AFUDC capitalization rate 7.0 % 7.1 % 7.2 %  Electric Transmission: In October 2015, Consumers became registered under NERC standards as a transmission owner, transmission planner, and transmission operator. Consumers had previously received approval from the MPSC in 2014 and from FERC in 2015 to reclassify $34 million of net plant assets from distribution to transmission. In March 2016, Consumers received FERC approval to begin collecting transmission revenues under MISO’s transmission tariff effective April 2016. Consumers completed the reclassification of plant assets from distribution to transmission in April 2016. Electric Plant Purchase: In December 2015, Consumers completed the purchase of a 540 ‑MW natural gas-fueled electric generating plant located in Jackson, Michigan for $155 million from AlphaGen Power LLC and DPC Juniper, LLC, affiliates of JPMorgan Chase & Co. Consumers purchased the plant to help address its future capacity requirements. Consumers accounted for the purchase as a business combination and prepared a valuation analysis of the assets acquired and liabilities assumed to determine their fair values. The cash consideration of $155 million was allocated based on the underlying fair values of the assets acquired, which were primarily plant, property, and equipment, and the liabilities assumed. No goodwill was recorded as a result of this purchase. The pro forma results of operations have not been presented, as the effects of the acquisition would not have been material to CMS Energy’s or Consumers’ consolidated results of operations in 2015. Assets Under Capital Leases and Financing Obligation : Presented in the following table are further details about changes in Consumers’ assets under capital leases and financing obligation :    In Millions  Years Ended December 31 2016 2015  Consumers  Balance at beginning of period $ 300 $ 295  Additions 13 17  Net retirements and other adjustments (3) (12)  Balance at end of period $ 310 $ 300  Assets under capital leases and financing obligation are presented as gross amounts. Accumulated amortization of assets under capital leases and financing obligation was $172 million at December 31, 2016 and $ 152 million at December 31, 2015 for Consumers. Depreciation and Amortization : Presented in the following table are further details about CMS Energy’s and Consumers’ accumulated depreciation and amortization:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  Utility plant assets $ 5,993 $ 5,674  Non-utility plant assets 63 73  Consumers  Utility plant assets $ 5,993 $ 5,674  Non-utility plant assets 1 2  Consumers depreciates utility property on an asset-group basis, in which it applies a single MPSC-approved depreciation rate to the gross investment in a particular class of property within the electric and gas segments. Consumers performs depreciation studies periodically to determine appropriate group lives. Presented in the following table are the composite depreciation rates for Consumers’ segment properties:    Years Ended December 31 2016 2015 2014  Electric utility property 3.9 % 3.5 % 3.5 %  Gas utility property 2.9 2.8 2.8  Other property 9.8 8.7 7.7  CMS Energy and Consumers record property repairs and minor property replacement as maintenance expense. CMS Energy and Consumers record planned major maintenance activities as operating expense unless the cost represents the acquisition of additional long-lived assets or the replacement of an existing long-lived asset. Pre sented in the following table are the components of CMS Energy’s and Consumers’ depreciation and amortization expe nse :    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Depreciation expense – plant, property, and equipment $ 687 $ 591 $ 551  Amortization expense  Software 96 70 50  Other intangible assets 3 4 4  Securitized regulatory assets 25 83 75  Other regulatory assets - 2 5  Total depreciation and amortization expense $ 811 $ 750 $ 685  Consumers  Depreciation expense – plant, property, and equipment $ 680 $ 586 $ 546  Amortization expense  Software 95 69 49  Other intangible assets 3 4 3  Securitized regulatory assets 25 83 75  Other regulatory assets - 2 5  Total depreciation and amortization expense $ 803 $ 744 $ 678  Presented in the following table is CMS Energy’s and Consumers’ estimated amortization expense on intangible assets for each of the next five years:    In Millions  2017 2018 2019 2020 2021  CMS Energy, including Consumers  Intangible asset amortization expense $ 115 $ 120 $ 112 $ 95 $ 77  Consumers  Intangible assets amortization expense $ 114 $ 119 $ 111 $ 94 $ 77  Intangible Assets: Included in net plant, property, and equipment are intangible assets. Presented in the following table are details about CMS Energy’s and Consumers’ intangible assets:    In Millions  December 31, 2016 December 31, 2015  Description Amortization Life in Years Gross Cost 1 Accumulated Amortization Gross Cost 1 Accumulated Amortization  CMS Energy, including Consumers  Software development 1 - 15 $ 853 $ 367 $ 734 $ 294  Rights of way 50 - 75 155 48 153 46  Franchises and consents 5 - 30 15 8 15 8  Leasehold improvements various 2 7 6 7 5  Other intangibles various 22 15 21 15  Total $ 1,052 $ 444 $ 930 $ 368  Consumers  Software development 3 - 15 $ 845 $ 363 $ 729 $ 291  Rights of way 50 - 75 155 48 153 46  Franchises and consents 5 - 30 15 8 15 8  Leasehold improvements various 2 7 6 7 5  Other intangibles various 21 15 21 15  Total $ 1,043 $ 440 $ 925 $ 365  1 For the year ended December 31, 20 16 , Consumers’ intangible asset additions were $141 million and intangible asset retirements were $23 million. For the year ended December 31, 20 15 , Consumers’ intangible asset additions were $ 140 million and there were no retirements . 2 Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended. Jointly Owned Regulated Utility Facilities Presented in the following table are Consumers’ investments in jointly owned regulated utility facilities at December 31, 20 16 :    In Millions, Except Ownership Share  J.H. Campbell Unit 3 Ludington Distribution  Ownership share 93.3 % 51.0 % various  Utility plant in service $ 1,648 $ 291 $ 206  Accumulated depreciation (529) (150) (63)  Construction work in progress 13 157 7  Net investment $ 1,132 $ 298 $ 150  Consumers includes its share of the direct expenses of the jointly owned plants in operating expenses. Consumers shares operation, maintenance, and other expenses of these jointly owned utility facilities in proportion to each participant’s undivided ownership interest. Consumers is required to provide only its share of financing for the jointly owned utility facilities.

Leases And Palisades Financing

Leases And Palisades Financing	12 Months Ended
	Dec. 31, 2016
Leases And Palisades Financing	10: Leases and Palisades Financing CMS Energy and Consumers lease various assets, including railcars, service vehicles, gas pipeline capacity, and buildings. In addition, CMS Energy and Consumers account for a number of their PPAs as capital and operating leases. Operating leases for coal-carrying railcars have original lease terms ranging from one to 15 years, expiring without extension provisions over the next seven years and with extension provisions over the next ten years. These leases contain fair market value extension and buyout provisions. Capital leases for Consumers’ vehicle fleet operations have a maximum term of 120 months with some having end-of-lease rental adjustment clauses based on the proceeds received from the sale or disposition of the ve hicles, and others having fixed- percentage purchase options. Consumers has capital leases for gas transportation pipelines to the D.E. Karn generating complex and Zeeland. The capital lease for the gas transportation pipeline into the D.E. Karn generating complex has a term of 15 years with a provision to extend the contract from month to month. The remaining term of the contract was five years at December 31, 20 16 . The capital lease for the gas transportation pipeline to Zeeland has a term of five years with a renewal provision of an additional five years at the end of the contract. The remaining term of the contract was one year at December 31, 20 16 . The remaining terms of Consumers’ long-term PPAs accounted for as leases range between one and 16 years. Most of these PPAs contain provisions at the end of the initial contract terms to renew the agreements annually. Presented in the following table are Consumers’ minimum lease expense and contingent rental expense. For each of the years ended December 31, 20 16 , 2015 , and 2014 , all of CMS Energy’s minimum lease expense and contingent rental expense were attributable to Consumers.    In Millions  Years Ended December 31 2016 2015 2014  Consumers  Minimum operating lease expense  PPAs $ 6 $ 6 $ 6  Other agreements 14 19 19  Contingent rental expense 1 82 82 85  1 Contingent rental expense is related to capital and operating lease PPAs and is based on delivery of energy and capacity in excess of minimum lease payments. Consumers is authorized by the MPSC to record operating lease payments as operating expense and recover the total cost from customers. Presented in the following table are the minimum annual rental commitments under Consumers’ non ‑cancelable leases at December 31, 20 16 . All of CMS Energy’s non ‑cancelable leases at December 31, 20 16 were attributable to Consumers.    In Millions  Capital Leases Palisades Financing Operating Leases  Consumers  2017 $ 15 $ 17 $ 20  2018 14 16 16  2019 14 15 10  2020 12 14 10  2021 11 14 10  2022 and thereafter 25 3 15  Total minimum lease payments $ 91 $ 79 $ 81  Less imputed interest 28 10  Present value of net minimum lease payments $ 63 $ 69  Less current portion 9 13  Non-current portion $ 54 $ 56  Palisades Financing In 2007, Consumers sold Palisades to Entergy and entered into a 15 -year PPA to purchase virtually all of the capacity and energy produced by Palisades, up to the annual average capacity of 798 MW. Consumers accounted for this transaction as a financing because of its continuing involvement with Palisades through security provided to Entergy for the PPA obligation and other arrangements. Palisades has therefore remained on Consumers’ consolidated balance sheets and Consumers has continued to depreciate it. At the time of the sale, Consumers recorded the sales proceeds as a financing obligation, and has subsequently recorded a portion of the payments under the PPA as interest expense and as a reduction of the financing obligation. Total amortization and interest charges under the financing were $17 million for the year ended December 31, 2016, $18 million for the year ended December 31, 2015, and $19 million for the year ended December 31, 2014. At December 31, 2016, the Palisades asset and financing obligation both had a balance of $69 million . The prices that Consumers pays under the PPA, and which it recovers from its electric customers through the PSCR, are presently higher than the cost to purchase electricity from the market. In December 2016, Consumers and Entergy reached an agreement t o terminate the PPA in May 2018 . In exchange for early termination, Consumers agreed to pay Entergy $172 million on the termination date. The agreement is contingent upon Consumers’ receipt of an MPSC order authorizing it to recover the termination payment from its electric customers. Consumers has indicated to the MPSC that it plans to request authorization to recover the termination payment through securitization. In an order issued in January 2017, the MPSC indicated that it will make a final determination on the securitization filing by September 2017, after full evaluation of the prudency of the termination payment and of how the termination will impact Michigan’s electric reliability and resource adequacy. If the MPSC does not approve Consumers’ request by September 30, 2017, the agreement will be null and void (unless otherwise extended) and the PPA will continue until April 2022 under its original terms. The amounts shown in the table above reflect the original terms of the PPA. Because Consumers accounted for its sale of Palisades to Entergy as a financing transaction, the early termination of the PPA represents a substantial modification of the terms of an existing debt instrument, and Consumers will therefore account for the termination agreement as an extinguishment of debt. Accordingly, in the period in which the termination agreement becomes effective, Consumers will remove from its consolidated balance sheets the existing financing obligation and will record a new financing obligation and a regulatory asset. Consumers will amortize the new financing obligation and will continue to depreciate the Palisades asset until the date of the PPA termination in May 2018 (assuming such termination occurs), when it will recognize the sale of Palisades.
Consumers Energy Company [Member]
Leases And Palisades Financing	10: Leases and Palisades Financing CMS Energy and Consumers lease various assets, including railcars, service vehicles, gas pipeline capacity, and buildings. In addition, CMS Energy and Consumers account for a number of their PPAs as capital and operating leases. Operating leases for coal-carrying railcars have original lease terms ranging from one to 15 years, expiring without extension provisions over the next seven years and with extension provisions over the next ten years. These leases contain fair market value extension and buyout provisions. Capital leases for Consumers’ vehicle fleet operations have a maximum term of 120 months with some having end-of-lease rental adjustment clauses based on the proceeds received from the sale or disposition of the ve hicles, and others having fixed- percentage purchase options. Consumers has capital leases for gas transportation pipelines to the D.E. Karn generating complex and Zeeland. The capital lease for the gas transportation pipeline into the D.E. Karn generating complex has a term of 15 years with a provision to extend the contract from month to month. The remaining term of the contract was five years at December 31, 20 16 . The capital lease for the gas transportation pipeline to Zeeland has a term of five years with a renewal provision of an additional five years at the end of the contract. The remaining term of the contract was one year at December 31, 20 16 . The remaining terms of Consumers’ long-term PPAs accounted for as leases range between one and 16 years. Most of these PPAs contain provisions at the end of the initial contract terms to renew the agreements annually. Presented in the following table are Consumers’ minimum lease expense and contingent rental expense. For each of the years ended December 31, 20 16 , 2015 , and 2014 , all of CMS Energy’s minimum lease expense and contingent rental expense were attributable to Consumers.    In Millions  Years Ended December 31 2016 2015 2014  Consumers  Minimum operating lease expense  PPAs $ 6 $ 6 $ 6  Other agreements 14 19 19  Contingent rental expense 1 82 82 85  1 Contingent rental expense is related to capital and operating lease PPAs and is based on delivery of energy and capacity in excess of minimum lease payments. Consumers is authorized by the MPSC to record operating lease payments as operating expense and recover the total cost from customers. Presented in the following table are the minimum annual rental commitments under Consumers’ non ‑cancelable leases at December 31, 20 16 . All of CMS Energy’s non ‑cancelable leases at December 31, 20 16 were attributable to Consumers.    In Millions  Capital Leases Palisades Financing Operating Leases  Consumers  2017 $ 15 $ 17 $ 20  2018 14 16 16  2019 14 15 10  2020 12 14 10  2021 11 14 10  2022 and thereafter 25 3 15  Total minimum lease payments $ 91 $ 79 $ 81  Less imputed interest 28 10  Present value of net minimum lease payments $ 63 $ 69  Less current portion 9 13  Non-current portion $ 54 $ 56  Palisades Financing In 2007, Consumers sold Palisades to Entergy and entered into a 15 -year PPA to purchase virtually all of the capacity and energy produced by Palisades, up to the annual average capacity of 798 MW. Consumers accounted for this transaction as a financing because of its continuing involvement with Palisades through security provided to Entergy for the PPA obligation and other arrangements. Palisades has therefore remained on Consumers’ consolidated balance sheets and Consumers has continued to depreciate it. At the time of the sale, Consumers recorded the sales proceeds as a financing obligation, and has subsequently recorded a portion of the payments under the PPA as interest expense and as a reduction of the financing obligation. Total amortization and interest charges under the financing were $17 million for the year ended December 31, 2016, $18 million for the year ended December 31, 2015, and $19 million for the year ended December 31, 2014. At December 31, 2016, the Palisades asset and financing obligation both had a balance of $69 million . The prices that Consumers pays under the PPA, and which it recovers from its electric customers through the PSCR, are presently higher than the cost to purchase electricity from the market. In December 2016, Consumers and Entergy reached an agreement t o terminate the PPA in May 2018 . In exchange for early termination, Consumers agreed to pay Entergy $172 million on the termination date. The agreement is contingent upon Consumers’ receipt of an MPSC order authorizing it to recover the termination payment from its electric customers. Consumers has indicated to the MPSC that it plans to request authorization to recover the termination payment through securitization. In an order issued in January 2017, the MPSC indicated that it will make a final determination on the securitization filing by September 2017, after full evaluation of the prudency of the termination payment and of how the termination will impact Michigan’s electric reliability and resource adequacy. If the MPSC does not approve Consumers’ request by September 30, 2017, the agreement will be null and void (unless otherwise extended) and the PPA will continue until April 2022 under its original terms. The amounts shown in the table above reflect the original terms of the PPA. Because Consumers accounted for its sale of Palisades to Entergy as a financing transaction, the early termination of the PPA represents a substantial modification of the terms of an existing debt instrument, and Consumers will therefore account for the termination agreement as an extinguishment of debt. Accordingly, in the period in which the termination agreement becomes effective, Consumers will remove from its consolidated balance sheets the existing financing obligation and will record a new financing obligation and a regulatory asset. Consumers will amortize the new financing obligation and will continue to depreciate the Palisades asset until the date of the PPA termination in May 2018 (assuming such termination occurs), when it will recognize the sale of Palisades.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2016
Asset Retirement Obligations	11: A sset R etirement O bligations CMS Energy and Consumers record the fair value of the cost to remove assets at the end of their useful lives, if there is a l egal obligation to remove them. If a reasonable estimate of fair value cannot be made in the period in which the ARO is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. CMS Energy and Consumers have not recorded liabilities for assets that have insignificant cumulative disposal costs, such as substation batteries. CMS Energy and Consumers calculate the fair value of ARO liabilities using an expected present-value technique that reflects assumptions about costs and inflation, and uses a credit-adjusted risk-free rate to discount the expected cash flows. CMS Energy’s ARO liabilities are primarily at Consumers. As a regulated entity, Consumers defers the effects of any changes in assumptions on the fair values of its ARO liabilities, adjusting the associated regulatory assets or liabilities rather than recognizing such effects in earnings. Presented below are the categories of assets that CMS Energy and Consumers have legal obligations to remove at the end of their useful lives and for which they have an ARO liability recorded:    Company and ARO Description In-Service Date Long-Lived Assets  CMS Energy, including Consumers  Closure of gas treating plant and gas wells Various Gas transmission and storage  Closure of coal ash disposal areas Various Generating plants coal ash areas  Gas distribution cut, purge, and cap Various Gas distribution mains and services  Asbestos abatement 1973 Electric and gas utility plant  Closure of renewable generation assets 2012,2014,2016 Wind and solar generation facilities  Consumers  Closure of coal ash disposal areas Various Generating plants coal ash areas  Gas distribution cut, purge, and cap Various Gas distribution mains and services  Asbestos abatement 1973 Electric and gas utility plant  Closure of renewable generation assets 2012,2014,2016 Wind and solar generation facilities  No assets have been restricted for purposes of settling AROs. Presented in the following tables are the changes in CMS Energy’s and Consumers’ ARO liabilities:    In Millions  ARO ARO  Liability Cash flow Liability  Company and ARO Description 12/31/2015 Incurred Settled Accretion Revisions 12/31/2016  CMS Energy, including Consumers  Consumers $ 438 $ 3 $ (18) $ 23 $ - $ 446  Gas treating plant and gas wells 1 - - - - 1  Total CMS Energy $ 439 $ 3 $ (18) $ 23 $ - $ 447  Consumers  Coal ash disposal areas $ 200 $ - $ (8) $ 9 $ - $ 201  Gas distribution cut, purge, and cap 178 2 (9) 11 - 182  Asbestos abatement 54 - (1) 3 - 56  Renewable generation assets 6 1 - - - 7  Total Consumers $ 438 $ 3 $ (18) $ 23 $ - $ 446     In Millions  ARO ARO  Liability Cash flow Liability  Company and ARO Description 12/31/2014 Incurred Settled Accretion Revisions 12/31/2015  CMS Energy, including Consumers  Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438  Gas treating plant and gas wells 1 - - - - 1  Total CMS Energy $ 340 $ 11 $ (6) $ 20 $ 74 $ 439  Consumers  Coal ash disposal areas $ 120 $ - $ - $ 6 $ 74 $ 200  Gas distribution cut, purge, and cap 162 11 (6) 11 - 178  Asbestos abatement 51 - - 3 - 54  Renewable generation assets 6 - - - - 6  Total Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438  In 2015, Consumers increased its ARO liability for coal ash disposal areas. The increase was attributable to proposed changes in state regulations based on the EPA’s final rule regarding CCRs, which provided Consumers with sufficient information to reasonably estimate an additional ARO liability associated with closure work at certain waste management facilities.
Consumers Energy Company [Member]
Asset Retirement Obligations	11: A sset R etirement O bligations CMS Energy and Consumers record the fair value of the cost to remove assets at the end of their useful lives, if there is a l egal obligation to remove them. If a reasonable estimate of fair value cannot be made in the period in which the ARO is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. CMS Energy and Consumers have not recorded liabilities for assets that have insignificant cumulative disposal costs, such as substation batteries. CMS Energy and Consumers calculate the fair value of ARO liabilities using an expected present-value technique that reflects assumptions about costs and inflation, and uses a credit-adjusted risk-free rate to discount the expected cash flows. CMS Energy’s ARO liabilities are primarily at Consumers. As a regulated entity, Consumers defers the effects of any changes in assumptions on the fair values of its ARO liabilities, adjusting the associated regulatory assets or liabilities rather than recognizing such effects in earnings. Presented below are the categories of assets that CMS Energy and Consumers have legal obligations to remove at the end of their useful lives and for which they have an ARO liability recorded:    Company and ARO Description In-Service Date Long-Lived Assets  CMS Energy, including Consumers  Closure of gas treating plant and gas wells Various Gas transmission and storage  Closure of coal ash disposal areas Various Generating plants coal ash areas  Gas distribution cut, purge, and cap Various Gas distribution mains and services  Asbestos abatement 1973 Electric and gas utility plant  Closure of renewable generation assets 2012,2014,2016 Wind and solar generation facilities  Consumers  Closure of coal ash disposal areas Various Generating plants coal ash areas  Gas distribution cut, purge, and cap Various Gas distribution mains and services  Asbestos abatement 1973 Electric and gas utility plant  Closure of renewable generation assets 2012,2014,2016 Wind and solar generation facilities  No assets have been restricted for purposes of settling AROs. Presented in the following tables are the changes in CMS Energy’s and Consumers’ ARO liabilities:    In Millions  ARO ARO  Liability Cash flow Liability  Company and ARO Description 12/31/2015 Incurred Settled Accretion Revisions 12/31/2016  CMS Energy, including Consumers  Consumers $ 438 $ 3 $ (18) $ 23 $ - $ 446  Gas treating plant and gas wells 1 - - - - 1  Total CMS Energy $ 439 $ 3 $ (18) $ 23 $ - $ 447  Consumers  Coal ash disposal areas $ 200 $ - $ (8) $ 9 $ - $ 201  Gas distribution cut, purge, and cap 178 2 (9) 11 - 182  Asbestos abatement 54 - (1) 3 - 56  Renewable generation assets 6 1 - - - 7  Total Consumers $ 438 $ 3 $ (18) $ 23 $ - $ 446     In Millions  ARO ARO  Liability Cash flow Liability  Company and ARO Description 12/31/2014 Incurred Settled Accretion Revisions 12/31/2015  CMS Energy, including Consumers  Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438  Gas treating plant and gas wells 1 - - - - 1  Total CMS Energy $ 340 $ 11 $ (6) $ 20 $ 74 $ 439  Consumers  Coal ash disposal areas $ 120 $ - $ - $ 6 $ 74 $ 200  Gas distribution cut, purge, and cap 162 11 (6) 11 - 178  Asbestos abatement 51 - - 3 - 54  Renewable generation assets 6 - - - - 6  Total Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438  In 2015, Consumers increased its ARO liability for coal ash disposal areas. The increase was attributable to proposed changes in state regulations based on the EPA’s final rule regarding CCRs, which provided Consumers with sufficient information to reasonably estimate an additional ARO liability associated with closure work at certain waste management facilities.

Retirement Benefits

Retirement Benefits	12 Months Ended
	Dec. 31, 2016
Retirement Benefits	12: R etirement B enefits Benefit Plans: CMS Energy and Consumers provide pension, OPEB, and other retirement benefits to employees under a number of different plans. These plans include: · a non ‑contributory, qualified DB Pension Plan (closed to new non ‑union participants as of July 1, 2003 and closed to new union partic ipants as of September 1, 2005) · a qualified Cash Balance Pension Plan for certain employees hired between J uly 1, 2003 and August 31, 2005 · a non ‑contributory, qualified DCCP for employees hire d on or after September 1, 2005 · benefits to certain management employees under a non ‑contributory, nonqualified DB SERP (closed to new par ticipants as of March 31, 2006) · a non ‑contributory, non qualified DC SERP for certain management employees hired or pro moted on or after April 1, 2006 · a contributory, qualified d efined contribution 401(k) plan · health care and life insura nce benefits under an OPEB Plan DB Pension Plan: Participants in the DB Pension Plan include present and former employees of CMS Energy and Consumers, including certain present and former affiliates and subsidiaries. DB Pension Plan trust assets are not distinguishable by company. DCCP and Cash Balance Pension Plan: CMS Energy and Consumers provide an employer contribution to the DCCP 401(k) plan for employees hired on or after September 1, 2005. The contribution ranges from five to seven percent of base pay, depending on years of service. Employees are not required to contribute in order to receive the plan’s employer contribution. Participants in the Cash Balance Pension Plan, effective July 1, 2003 to August 31, 2005, also participate in the DCCP as of September 1, 2005. Additional pay credits under the Cash Balance Pension Plan were discontinued as of September 1, 2005 . DCCP expense for CMS Energy , including Consumers, was $20 million for the year ended December 31, 2016 , $16 million for the year ended December 31, 2015 , and $13 million for the year ended December 31, 2014 . DCCP expense for Consumers was $19 million for the year ended December 31, 2016 , $16 million for the year ended December 31, 2015 , and $13 million for the year ended December 31, 2014. DB SERP: The DB SERP is a non qualified plan as defined by the Internal Revenue Code. DB SERP benefits are paid from a rabbi trust established in 1988. DB SERP rabbi trust earnings are taxable. Presented in the following table are the fair values of trust assets, ABO, and contributions for CMS Energy’s and Consumers’ DB SERP:    In Millions  Years Ended December 31 2016 2015  CMS Energy, including Consumers  Trust assets $ 144 $ 148  ABO 143 140  Contributions - 25  Consumers  Trust assets $ 104 $ 106  ABO 101 97  Contributions - 17  DC SERP: On April 1, 2006, CMS Energy and Consumers implemented a DC SERP and froze further new participation in the DB SERP. The DC SERP provides participants benefits ranging from 5 percent to 15 percent of total compensation. The DC SERP requires a minimum of five years of participation before vesting. CMS Energy’s and Consumers’ contributions to the plan, if any, are placed in a grantor trust. For CMS Energy and Consumers, trust assets were $3 million and $2 million at December 31, 2016 and 2015 . DC SERP assets are included in other non ‑current assets on CMS Energy’s and Consumers’ consolidated balance sheets. CMS Energy’s and Consumers’ DC SERP expense was less than $ 1 million for each of the years ended December 31, 2016 , 2015 , and 2014 . 401(k) Plan: T he 401(k) plan employer match equal s 100 percent of eligible contributions up to the first three percent of an employee’s wages and 50 percent of eligible contributions up to the next two percent of an employee’s wages . The total 401(k) plan cost for CMS Energy, including Consumers , was $24 million for the year ended December 31, 2016 , $ 19 million for the year ended December 31, 2015 , and $ 18 million for the year ended December 31, 2014 . The total 401(k) plan cost for Consumers was $23 million for the year ended December 31, 2016 , $19 million for the year ended December 31, 2015 , and $ 18 million for the year ended December 31, 2014. OPEB Plan: Participants in the OPEB Plan include all regular full-time employees covered by the employee health care plan on the day before retirement from either CMS Energy or Consumers at age 55 or older with at least ten full years of applicable continuous service. Regular full-time employees who qualify for DB Pension Plan disability retirement or are disabled and covered by the DCCP and who have 15 years of applicable continuous service may also participate in the OPEB Plan. Retiree health care costs were based on the assumption that costs would increase 7.00 percent in 201 7 and 7.25 percent in 201 6 for those under 65 and would increase 7.75 percent in 2017 and 8.00 percent in 2016 for those over 65 . The rate of increase was assumed to decline to 4.75 percent by 2027 and thereafter for all retirees . The assumptions used in the health care cost-trend rate affect service, interest, and PBO costs. Presented in the following table are the effects of a one-percentage-point change in the health care cost-trend assumption:    In Millions  One Percentage One Percentage  Year Ended December 31, 2016 Point Increase Point Decrease  CMS Energy, including Consumers  Effect on total service and interest cost component $ 13 $ (10)  Effect on PBO 201 (163)  Consumers  Effect on total service and interest cost component $ 13 $ (10)  Effect on PBO 196 (159)  Assumptions: Presented in the following table are the weighted-average assumptions used in CMS Energy’s and Consumers’ retirement benefits plans to determine benefit obligations and net periodic benefit cost:    December 31 2016 2015 2014  CMS Energy, including Consumers  Weighted average for benefit obligations 1  Discount rate 2,3  DB Pension Plan 4.30 % 4.52 % 4.10 %  DB SERP 4.16 4.43 4.10  OPEB Plan 4.49 4.70 4.30  Rate of compensation increase  DB Pension Plan 3.60 3.00 3.00  DB SERP 5.50 5.50 5.50  Weighted average for net periodic benefit cost 1  Service cost discount rate 2,3  DB Pension Plan 4.79 4.10 4.90  DB SERP 4.87 4.10 4.90  OPEB Plan 4.75 4.30 5.10  Interest cost discount rate 2,3  DB Pension Plan 3.66 4.10 4.90  DB SERP 3.64 4.10 4.90  OPEB Plan 3.89 4.30 5.10  Expected long-term rate of return on plan assets 4  DB Pension Plan 7.25 7.50 7.50  OPEB Plan 7.25 7.25 7.25  Rate of compensation increase  DB Pension Plan 3.00 3.00 3.00  DB SERP 5.50 5.50 5.50  1 The mortality assumption for benefit obligations was based on the RP- 2014 mortality table, with projection scales MP-2016 for 2016, MP-2015 for 2015, and MP-2014 for 2014 . The mortality assumption for net periodic benefit cost for 2016 and 2015 was based on the RP - 2014 mortality table , with projection scales MP-2015 for 2016 and MP-2014 for 2015, and for 201 4 was based on the RP - 2000 mortality table. 2 The discount rate reflects the rate at which benefits could be effectively settled and is equal to the equivalent single rate resulting from a yield - curve analysis. This analysis incorporated the projected benefit payments specific to CMS Energy’s and Consumers’ DB Pension Plan and OPEB Plan and the yields on high - quality corporate bonds rated Aa or better. 3 In January 2016, CMS Energy and Consumers changed the method they use to determine the discount rate used to calculate the service cost and interest cost components of net periodic benefit costs for the DB Pension and OPEB Plans. Historically, the discount rate used for this purpose represented a single weighted - average rate derived from the yield curve used to determine the benefit obligation. CMS Energy and Consumers have elected to use instead a full - yield - curve approach in the estimation of service cost and interest cost ; this approach is more accurate in that it applies individual spot rates along the yield curve to future projected benefit payments based on the time of payment. This change represented a change in accounting estimate and did not impact years prior to 2016. As a result of changing to the full-yield-curve approach to determine the discount rate, for the year ended December 31, 2016, the service cost and interest cost components of net periodic benefit costs were reduced by $23 million for the DB Pension Plan and $12 million for the OPEB Plan for CMS Energy and by $22 million for the DB Pension Plan and $11 million for the OPEB Plan for Consumers. 4 CMS Energy and Consumers determined the long-term rate of return using historical market returns, the present and expected future economic environment, the capital market principles of risk and return, and the expert opinions of individuals and firms with financial market knowledge. CMS Energy and Consumers considered the asset allocation of the portfolio in forecasting the future expected total return of the portfolio. The goal was to determine a long-term rate of return that could be incorporated into the planning of future cash flow requirements in conjunction with the change in the liability. Annually, CMS Energy and Consumers review for reasonableness and appropriateness the forecasted returns for various classes of assets used to construct an expected return model. CMS Energy’s and Consumers’ expected long-term rate of return on DB Pension Plan assets was 7. 2 5 percent in 2016 . The actual return (loss) on DB Pension Plan assets was 8.0 percent in 2016 , (2.0) percent in 2015 , and 7.4 percent in 2014 . Costs: 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 and DB SERP OPEB Plan  Years Ended December 31 2016 2015 2014 2016 2015 2014  CMS Energy, including Consumers  Net periodic cost (credit)  Service cost $ 42 $ 50 $ 42 $ 18 $ 25 $ 20  Interest cost 90 108 105 46 58 56  Expected return on plan assets (147) (138) (135) (85) (91) (88)  Amortization of:  Net loss 71 97 60 21 21 2  Prior service cost (credit) 4 1 1 (41) (41) (41)  Net periodic cost (credit) $ 60 $ 118 $ 73 $ (41) $ (28) $ (51)  Consumers  Net periodic cost (credit)  Service cost $ 41 $ 49 $ 41 $ 17 $ 25 $ 20  Interest cost 87 103 100 45 56 54  Expected return on plan assets (143) (134) (131) (80) (86) (83)  Amortization of:  Net loss 68 93 59 22 22 3  Prior service cost (credit) 4 1 1 (40) (40) (40)  Net periodic cost (credit) $ 57 $ 112 $ 70 $ (36) $ (23) $ (46)  Presented in the following table are the estimated net loss and prior service cost (credit) that will be amortized into net periodic benefit cost in 201 7 from or to the associated regulatory asset and AOCI:    In Millions  DB Pension Plan OPEB Plan  CMS Energy, including Consumers  Regulatory asset $ 82 $ (2)  AOCI 2 (2)  Consumers  Regulatory asset $ 82 $ (2)  CMS Energy and Consumers amortize net gains and losses in excess of ten percent of the greater of the PBO or the MRV over the average remaining service period. The estimated period of amortization of gains and losses for CMS Energy and Consumers was ten years for the DB Pension Plan for the years ended December 31, 2016 , 2015 , and 2014 and for the OPEB Plan was 11 years for the year ended December 31, 2016 and 13 years for the years ended December 31, 2015 and 2014 . Prior service cost (credit) amortization is established in the year in which the prior service cost (credit) first occurred, and is based on the same amortization period for all future years until the prior service cost (credit) is fully amortized. CMS Energy and Consumers had a new prior service credit for OPEB in 2015 and new prior service cost for the DB Pension Plan in 2015 . The estimated pe riod of amortization of the s e new prior service costs ( credit s) for CMS Energy and Consumers is ten years. CMS Energy and Consumers determine the MR V for DB Pension Plan assets as the fair value of plan assets on the measurement date, adjusted by the gains or losses that will not be admitted into the MRV until future years. CMS Energy and Consumers reflect each year’s gain or loss in the MRV in equal amounts over a five -year period beginning on the date the original amount was determined. CMS Energy and Consumers determine the MRV for OPEB Plan assets as the fair value of assets on the measurement date. Reconciliations: Presented in the following table are reconciliations of the funded status of CMS Energy’s and Consumers’ retirement benefits plans with their retirement benefits plans’ liabilities:    In Millions  DB Pension Plan DB SERP OPEB Plan  Years Ended December 31 2016 2015 2016 2015 2016 2015  CMS Energy, including Consumers  Benefit obligation at beginning of period $ 2,403 $ 2,547 $ 150 $ 156 $ 1,227 $ 1,378  Service cost 42 49 - 1 18 25  Interest cost 85 102 5 6 46 58  Plan amendments - 13 - - - (25)  Actuarial (gain) loss 196 1 (153) 1 4 (5) 171 1 (152) 1  Benefits paid (164) (155) (8) (8) (54) (57)  Benefit obligation at end of period $ 2,562 $ 2,403 $ 151 $ 150 $ 1,408 $ 1,227  Plan assets at fair value at beginning of period $ 2,013 $ 1,979 $ - $ - $ 1,208 $ 1,265  Actual return on plan assets 152 (36) - - 109 (29)  Company contribution 100 225 8 8 - 29  Actual benefits paid (164) (155) (8) (8) (53) (57)  Plan assets at fair value at end of period $ 2,101 $ 2,013 $ - $ - $ 1,264 $ 1,208  Funded status $ (461) 2 $ (390) 2 $ (151) $ (150) $ (144) $ (19)  Consumers  Benefit obligation at beginning of period $ 106 $ 111 $ 1,188 $ 1,336  Service cost - 1 17 25  Interest cost 4 4 45 56  Plan amendments - - - (24)  Actuarial (gain) loss 4 (5) 167 1 (150) 1  Benefits paid (5) (5) (52) (55)  Benefit obligation at end of period $ 109 $ 106 $ 1,365 $ 1,188  Plan assets at fair value at beginning of period $ - $ - $ 1,133 $ 1,186  Actual return on plan assets - - 103 (27)  Company contribution 5 5 - 29  Actual benefits paid (5) (5) (52) (55)  Plan assets at fair value at end of period $ - $ - $ 1,184 $ 1,133  Funded status $ (109) $ (106) $ (181) $ (55)  1 The actuarial loss for 2016 was primarily the result of claims, experience, and lowering the discount rates used in calculating the plans’ obligations. The actuarial gain for 2015 was primarily the result of increasing the discount rates used in calculating the plans’ obligations. 2 At December 31, 2016 , $ 441 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses. At December 31, 2015 , $ 368 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses. Presented in the following table is the classification of CMS Energy’s and Consumers’ retirement benefit plans’ liabilities:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  Current liabilities  DB SERP $ 8 $ 8  Non-current liabilities  DB Pension Plan 461 390  DB SERP 143 142  OPEB Plan 144 19  Consumers  Current liabilities  DB SERP $ 5 $ 5  Non-current liabilities  DB Pension Plan 441 368  DB SERP 104 101  OPEB Plan 181 55  Presented in the following table are the DB Pension Plan PBO, ABO, and fair value of plan assets:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  DB Pension Plan PBO $ 2,562 $ 2,403  DB Pension Plan ABO 2,250 2,140  Fair value of DB Pension Plan assets 2,101 2,013  Items Not Yet Recognized as a Component of Net Periodic Benefit Cost: Presented in the following table are the amounts recognized in regulatory assets and AOCI that have not been recognized as components of net periodic benefit cost. For additional details on regulatory assets and liabilities, see Note 3, Regulatory Matters.    In Millions  DB Pension Plan and DB SERP OPEB Plan  Years Ended December 31 2016 2015 2016 2015  CMS Energy, including Consumers  Regulatory assets  Net loss $ 1,062 $ 944 $ 483 $ 360  Prior service cost (credit) 15 19 (187) (227)  Regulatory assets $ 1,077 $ 963 $ 296 $ 133  AOCI  Net loss (gain) 93 86 (8) (11)  Prior service cost (credit) 1 1 (6) (8)  Total amounts recognized in regulatory assets and AOCI $ 1,171 $ 1,050 $ 282 $ 114  Consumers  Regulatory assets  Net loss $ 1,062 $ 944 $ 483 $ 360  Prior service cost (credit) 15 19 (187) (227)  Regulatory assets $ 1,077 $ 963 $ 296 $ 133  AOCI  Net loss 33 29 - -  Total amounts recognized in regulatory assets and AOCI $ 1,110 $ 992 $ 296 $ 133  Plan Assets: Presented in the following tables are the fair values of CMS Energy’s DB Pension Plan and OPEB Plan assets, by asset category and by level within the fair value hierarchy. For additional details regarding the fair value hierarchy, see Note 6, Fair Value Measurements.    In Millions  DB Pension Plan  December 31, 2016 December 31, 2015  Total Level 1 Level 2 Total Level 1 Level 2  CMS Energy, including Consumers  Cash and short-term investments $ 110 $ 110 $ - $ 215 $ 215 $ -  U.S. government and agencies securities 1 - 1 19 - 19  Corporate debt 266 - 266 243 - 243  State and municipal bonds 9 - 9 8 - 8  Foreign corporate bonds 25 - 25 16 - 16  Mutual funds 571 571 - 538 538 -  $ 982 $ 681 $ 301 $ 1,039 $ 753 $ 286  Pooled funds 1,119 974  Total $ 2,101 $ 2,013     In Millions  OPEB Plan  December 31, 2016 December 31, 2015  Total Level 1 Level 2 Total Level 1 Level 2  CMS Energy, including Consumers  Cash and short-term investments $ 39 $ 39 $ - $ 51 $ 51 $ -  U.S. government and agencies securities - - - 3 - 3  Corporate debt 38 - 38 34 - 34  State and municipal bonds 1 - 1 1 - 1  Foreign corporate bonds 4 - 4 2 - 2  Common stocks 44 44 - 54 54 -  Mutual funds 563 563 - 456 456 -  $ 689 $ 646 $ 43 $ 601 $ 561 $ 40  Pooled funds 575 607  Total $ 1,264 $ 1,208  Cash and Short-Term Investments: Cash and short-term investments consist of money market funds with daily liquidity. U.S. Government and Agencies Securities: U.S. government and agencies securities consist of U.S. Treasury notes and other debt securities backed by the U.S. government and related agencies. These securities were valued based on quoted market prices. Corporate Debt: Corporate debt investments consisted of investment grade bonds of U.S. issuers from diverse industries. These securities are valued based on quoted market prices, when available, or yields presently available on comparable securities of issuers with similar credit ratings. State and Municipal Bonds: State and municipal bonds were valued using a matrix-pricing model that incorporates Level 2 market-based information. The fair value of the bonds was derived from various observable inputs, including benchmark yields, reported securities trades, broker/dealer quotes, bond ratings, and general information on market movements for investment grade state and municipal securities normally considered by market participants when pricing such debt securities. Foreign Corporate Bonds: Foreign corporate debt securities were valued based on quoted market prices, when available, or on yields available on comparable securities of issuers with similar credit ratings. Common Stocks: Common stocks in the OPEB Plan consist of equity securities with low transaction costs that were actively managed and tracked by the S&P 500 Index. These securities were valued at their quoted closing prices. Mutual Funds: Mutual funds represent shares in registered investment companies that are priced based on the daily quoted NAVs that are publicly available and are the basis for transactions to buy or sell shares in the funds. Pooled Funds: Pooled funds include both common and collective trust funds as well as special funds that contain only employee benefit plan assets from two or more unrelated benefit plans. Presented in the following table are the investment components of these funds:    DB Pension Plan OPEB Plan  December 31 2016 2015 2016 2015  U.S. equity securities 67 % 62 % 72 % 58 %  Foreign equity securities 16 18 13 13  U.S. fixed-income securities 9 11 8 22  Foreign fixed-income securities 4 6 4 5  Alternative investments 4 3 3 2  100 % 100 % 100 % 100 %  Since these investments were valued at their NAV as a practical expedient, they are not classified in the fair value hierarchy. Target Asset Allocations: CMS Energy’s target asset allocation for DB Pension Plan assets is 53 percent equity, 32 percent fixed income, and 15 percent alternative-strategy investments. This target asset allocation is expected to continue to maximize the long-term return on plan assets, while maintaining a prudent level of risk. The level of acceptable risk is a function of the liabilities of the plan. Equity investments are diversified mostly across the S&P 500 Index, with lesser allocations to the S&P MidCap and SmallCap Indexes and Foreign Equity Funds. Fixed-income investments are diversified across investment grade instruments of government and corporate issuers as well as high-yield and global bond funds. Alternative strategies are diversified across absolute return investment approaches and global tactical asset allocation. CMS Energy use s annual liability measurements, quarterly portfolio reviews, and periodic asset/liability studies to evaluate the need for adjustments to the portfolio allocation. CMS Energy established union and non ‑union VEBA trusts to fund future retiree health and life insurance benefits. These trusts are funded through the ratemaking process for Consumers and through direct contributions from the non ‑utility subsidiaries. CMS Energy’s target asset allocation for the health trusts is 50 percent equity, 30 percent fixed income, and 20 percent alternative - strategy investments. CMS Energy’s target asset allocation for the life trusts is 42 percent equity, 28 percent fixed income, and 30 percent alternative - strategy investments . These target allocations are expected to continue to maximize the long-term return on plan assets, while maintaining a prudent level of risk. The level of acceptable risk is a function of the liabilities of the plan s . Equity investments are diversified mostly across the S&P 500 Index, with lesser allocations to the S&P SmallCap Index and Foreign Equity Funds. Fixed-income investments are diversified across investment grade instruments of government and corporate issuers. Alternative strategies are diversified across absolute return investment approaches and global tactical asset allocation. CMS Energy use s annual liability measurements, quarterly portfolio reviews, and periodic asset/liability studies to evaluate the need for adjustments to the portfolio allocation. Contributions: Presented in the following table are the contributions to CMS Energy’s and Consumers’ OPEB Plan and DB Pension Plan:    In Millions  Years Ended December 31 2016 2015  CMS Energy, including Consumers  OPEB Plan $ - $ 29  DB Pension Plan 100 225  Consumers  OPEB Plan $ - $ 29  DB Pension Plan 93 209  Contributions comprise required amounts and discretionary contributions. Neither CMS Energy nor Consumers plans to contribute to the OPEB or DB Pension Plans in 2017. Actual future contributions will depend on future investment performance, discount rates, and various factors related to the DB Pension Plan and OPEB Plan participants. Following amendments to the OPEB Plan in July 2013, Consumers’ OPEB costs decreased substantially and, as a result, the OPEB Plan was fully funded at December 31, 2013. In May 2014, Consumers filed an application with the MPSC requesting approval to suspend contributions to Consumers’ OPEB Plan during 2014 and 2015 if the OPEB Plan continued to be fully funded. Consumers’ electric and gas rates still reflect the higher OPEB costs, and previous MPSC orders required Consumers to contribute to the OPEB Plan the associated amount collected in rates annually. In September 2014, the MPSC approved a settlement agreement addressing Consumers’ OPEB Plan funding application. Under the settlement agreement, Consumers contributed $ 25 million to the plan in 2014 and $ 29 million in February 2015. Consumers will suspend further contributions until the MPSC determines funding requirements in future general rate cases. Benefit Payments: Presented in the following table are the expected benefit payments for each of the next five years and the five-year period thereafter:    In Millions  DB Pension Plan DB SERP OPEB Plan  CMS Energy, including Consumers  2017 $ 153 $ 8 $ 59  2018 159 8 63  2019 163 9 66  2020 165 11 69  2021 166 10 72  2022-2026 827 50 385  Consumers  2017 $ 149 $ 5 $ 57  2018 155 5 61  2019 159 6 64  2020 161 7 67  2021 161 7 70  2022-2026 803 32 371  Collective Bargaining Agreements: At December 31, 2016 , unions represented 39 percent of CMS Energy’s employees and 41 percent of Consumers’ employees. The UWUA represents Consumers’ operating, maintenance, construction, and call center employees. The USW represents Zeeland employees. Union contracts expire in 2020.
Consumers Energy Company [Member]
Retirement Benefits	12: R etirement B enefits Benefit Plans: CMS Energy and Consumers provide pension, OPEB, and other retirement benefits to employees under a number of different plans. These plans include: · a non ‑contributory, qualified DB Pension Plan (closed to new non ‑union participants as of July 1, 2003 and closed to new union partic ipants as of September 1, 2005) · a qualified Cash Balance Pension Plan for certain employees hired between J uly 1, 2003 and August 31, 2005 · a non ‑contributory, qualified DCCP for employees hire d on or after September 1, 2005 · benefits to certain management employees under a non ‑contributory, nonqualified DB SERP (closed to new par ticipants as of March 31, 2006) · a non ‑contributory, non qualified DC SERP for certain management employees hired or pro moted on or after April 1, 2006 · a contributory, qualified d efined contribution 401(k) plan · health care and life insura nce benefits under an OPEB Plan DB Pension Plan: Participants in the DB Pension Plan include present and former employees of CMS Energy and Consumers, including certain present and former affiliates and subsidiaries. DB Pension Plan trust assets are not distinguishable by company. DCCP and Cash Balance Pension Plan: CMS Energy and Consumers provide an employer contribution to the DCCP 401(k) plan for employees hired on or after September 1, 2005. The contribution ranges from five to seven percent of base pay, depending on years of service. Employees are not required to contribute in order to receive the plan’s employer contribution. Participants in the Cash Balance Pension Plan, effective July 1, 2003 to August 31, 2005, also participate in the DCCP as of September 1, 2005. Additional pay credits under the Cash Balance Pension Plan were discontinued as of September 1, 2005 . DCCP expense for CMS Energy , including Consumers, was $20 million for the year ended December 31, 2016 , $16 million for the year ended December 31, 2015 , and $13 million for the year ended December 31, 2014 . DCCP expense for Consumers was $19 million for the year ended December 31, 2016 , $16 million for the year ended December 31, 2015 , and $13 million for the year ended December 31, 2014. DB SERP: The DB SERP is a non qualified plan as defined by the Internal Revenue Code. DB SERP benefits are paid from a rabbi trust established in 1988. DB SERP rabbi trust earnings are taxable. Presented in the following table are the fair values of trust assets, ABO, and contributions for CMS Energy’s and Consumers’ DB SERP:    In Millions  Years Ended December 31 2016 2015  CMS Energy, including Consumers  Trust assets $ 144 $ 148  ABO 143 140  Contributions - 25  Consumers  Trust assets $ 104 $ 106  ABO 101 97  Contributions - 17  DC SERP: On April 1, 2006, CMS Energy and Consumers implemented a DC SERP and froze further new participation in the DB SERP. The DC SERP provides participants benefits ranging from 5 percent to 15 percent of total compensation. The DC SERP requires a minimum of five years of participation before vesting. CMS Energy’s and Consumers’ contributions to the plan, if any, are placed in a grantor trust. For CMS Energy and Consumers, trust assets were $3 million and $2 million at December 31, 2016 and 2015 . DC SERP assets are included in other non ‑current assets on CMS Energy’s and Consumers’ consolidated balance sheets. CMS Energy’s and Consumers’ DC SERP expense was less than $ 1 million for each of the years ended December 31, 2016 , 2015 , and 2014 . 401(k) Plan: T he 401(k) plan employer match equal s 100 percent of eligible contributions up to the first three percent of an employee’s wages and 50 percent of eligible contributions up to the next two percent of an employee’s wages . The total 401(k) plan cost for CMS Energy, including Consumers , was $24 million for the year ended December 31, 2016 , $ 19 million for the year ended December 31, 2015 , and $ 18 million for the year ended December 31, 2014 . The total 401(k) plan cost for Consumers was $23 million for the year ended December 31, 2016 , $19 million for the year ended December 31, 2015 , and $ 18 million for the year ended December 31, 2014. OPEB Plan: Participants in the OPEB Plan include all regular full-time employees covered by the employee health care plan on the day before retirement from either CMS Energy or Consumers at age 55 or older with at least ten full years of applicable continuous service. Regular full-time employees who qualify for DB Pension Plan disability retirement or are disabled and covered by the DCCP and who have 15 years of applicable continuous service may also participate in the OPEB Plan. Retiree health care costs were based on the assumption that costs would increase 7.00 percent in 201 7 and 7.25 percent in 201 6 for those under 65 and would increase 7.75 percent in 2017 and 8.00 percent in 2016 for those over 65 . The rate of increase was assumed to decline to 4.75 percent by 2027 and thereafter for all retirees . The assumptions used in the health care cost-trend rate affect service, interest, and PBO costs. Presented in the following table are the effects of a one-percentage-point change in the health care cost-trend assumption:    In Millions  One Percentage One Percentage  Year Ended December 31, 2016 Point Increase Point Decrease  CMS Energy, including Consumers  Effect on total service and interest cost component $ 13 $ (10)  Effect on PBO 201 (163)  Consumers  Effect on total service and interest cost component $ 13 $ (10)  Effect on PBO 196 (159)  Assumptions: Presented in the following table are the weighted-average assumptions used in CMS Energy’s and Consumers’ retirement benefits plans to determine benefit obligations and net periodic benefit cost:    December 31 2016 2015 2014  CMS Energy, including Consumers  Weighted average for benefit obligations 1  Discount rate 2,3  DB Pension Plan 4.30 % 4.52 % 4.10 %  DB SERP 4.16 4.43 4.10  OPEB Plan 4.49 4.70 4.30  Rate of compensation increase  DB Pension Plan 3.60 3.00 3.00  DB SERP 5.50 5.50 5.50  Weighted average for net periodic benefit cost 1  Service cost discount rate 2,3  DB Pension Plan 4.79 4.10 4.90  DB SERP 4.87 4.10 4.90  OPEB Plan 4.75 4.30 5.10  Interest cost discount rate 2,3  DB Pension Plan 3.66 4.10 4.90  DB SERP 3.64 4.10 4.90  OPEB Plan 3.89 4.30 5.10  Expected long-term rate of return on plan assets 4  DB Pension Plan 7.25 7.50 7.50  OPEB Plan 7.25 7.25 7.25  Rate of compensation increase  DB Pension Plan 3.00 3.00 3.00  DB SERP 5.50 5.50 5.50  1 The mortality assumption for benefit obligations was based on the RP- 2014 mortality table, with projection scales MP-2016 for 2016, MP-2015 for 2015, and MP-2014 for 2014 . The mortality assumption for net periodic benefit cost for 2016 and 2015 was based on the RP - 2014 mortality table , with projection scales MP-2015 for 2016 and MP-2014 for 2015, and for 201 4 was based on the RP - 2000 mortality table. 2 The discount rate reflects the rate at which benefits could be effectively settled and is equal to the equivalent single rate resulting from a yield - curve analysis. This analysis incorporated the projected benefit payments specific to CMS Energy’s and Consumers’ DB Pension Plan and OPEB Plan and the yields on high - quality corporate bonds rated Aa or better. 3 In January 2016, CMS Energy and Consumers changed the method they use to determine the discount rate used to calculate the service cost and interest cost components of net periodic benefit costs for the DB Pension and OPEB Plans. Historically, the discount rate used for this purpose represented a single weighted - average rate derived from the yield curve used to determine the benefit obligation. CMS Energy and Consumers have elected to use instead a full - yield - curve approach in the estimation of service cost and interest cost ; this approach is more accurate in that it applies individual spot rates along the yield curve to future projected benefit payments based on the time of payment. This change represented a change in accounting estimate and did not impact years prior to 2016. As a result of changing to the full-yield-curve approach to determine the discount rate, for the year ended December 31, 2016, the service cost and interest cost components of net periodic benefit costs were reduced by $23 million for the DB Pension Plan and $12 million for the OPEB Plan for CMS Energy and by $22 million for the DB Pension Plan and $11 million for the OPEB Plan for Consumers. 4 CMS Energy and Consumers determined the long-term rate of return using historical market returns, the present and expected future economic environment, the capital market principles of risk and return, and the expert opinions of individuals and firms with financial market knowledge. CMS Energy and Consumers considered the asset allocation of the portfolio in forecasting the future expected total return of the portfolio. The goal was to determine a long-term rate of return that could be incorporated into the planning of future cash flow requirements in conjunction with the change in the liability. Annually, CMS Energy and Consumers review for reasonableness and appropriateness the forecasted returns for various classes of assets used to construct an expected return model. CMS Energy’s and Consumers’ expected long-term rate of return on DB Pension Plan assets was 7. 2 5 percent in 2016 . The actual return (loss) on DB Pension Plan assets was 8.0 percent in 2016 , (2.0) percent in 2015 , and 7.4 percent in 2014 . Costs: 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 and DB SERP OPEB Plan  Years Ended December 31 2016 2015 2014 2016 2015 2014  CMS Energy, including Consumers  Net periodic cost (credit)  Service cost $ 42 $ 50 $ 42 $ 18 $ 25 $ 20  Interest cost 90 108 105 46 58 56  Expected return on plan assets (147) (138) (135) (85) (91) (88)  Amortization of:  Net loss 71 97 60 21 21 2  Prior service cost (credit) 4 1 1 (41) (41) (41)  Net periodic cost (credit) $ 60 $ 118 $ 73 $ (41) $ (28) $ (51)  Consumers  Net periodic cost (credit)  Service cost $ 41 $ 49 $ 41 $ 17 $ 25 $ 20  Interest cost 87 103 100 45 56 54  Expected return on plan assets (143) (134) (131) (80) (86) (83)  Amortization of:  Net loss 68 93 59 22 22 3  Prior service cost (credit) 4 1 1 (40) (40) (40)  Net periodic cost (credit) $ 57 $ 112 $ 70 $ (36) $ (23) $ (46)  Presented in the following table are the estimated net loss and prior service cost (credit) that will be amortized into net periodic benefit cost in 201 7 from or to the associated regulatory asset and AOCI:    In Millions  DB Pension Plan OPEB Plan  CMS Energy, including Consumers  Regulatory asset $ 82 $ (2)  AOCI 2 (2)  Consumers  Regulatory asset $ 82 $ (2)  CMS Energy and Consumers amortize net gains and losses in excess of ten percent of the greater of the PBO or the MRV over the average remaining service period. The estimated period of amortization of gains and losses for CMS Energy and Consumers was ten years for the DB Pension Plan for the years ended December 31, 2016 , 2015 , and 2014 and for the OPEB Plan was 11 years for the year ended December 31, 2016 and 13 years for the years ended December 31, 2015 and 2014 . Prior service cost (credit) amortization is established in the year in which the prior service cost (credit) first occurred, and is based on the same amortization period for all future years until the prior service cost (credit) is fully amortized. CMS Energy and Consumers had a new prior service credit for OPEB in 2015 and new prior service cost for the DB Pension Plan in 2015 . The estimated pe riod of amortization of the s e new prior service costs ( credit s) for CMS Energy and Consumers is ten years. CMS Energy and Consumers determine the MR V for DB Pension Plan assets as the fair value of plan assets on the measurement date, adjusted by the gains or losses that will not be admitted into the MRV until future years. CMS Energy and Consumers reflect each year’s gain or loss in the MRV in equal amounts over a five -year period beginning on the date the original amount was determined. CMS Energy and Consumers determine the MRV for OPEB Plan assets as the fair value of assets on the measurement date. Reconciliations: Presented in the following table are reconciliations of the funded status of CMS Energy’s and Consumers’ retirement benefits plans with their retirement benefits plans’ liabilities:    In Millions  DB Pension Plan DB SERP OPEB Plan  Years Ended December 31 2016 2015 2016 2015 2016 2015  CMS Energy, including Consumers  Benefit obligation at beginning of period $ 2,403 $ 2,547 $ 150 $ 156 $ 1,227 $ 1,378  Service cost 42 49 - 1 18 25  Interest cost 85 102 5 6 46 58  Plan amendments - 13 - - - (25)  Actuarial (gain) loss 196 1 (153) 1 4 (5) 171 1 (152) 1  Benefits paid (164) (155) (8) (8) (54) (57)  Benefit obligation at end of period $ 2,562 $ 2,403 $ 151 $ 150 $ 1,408 $ 1,227  Plan assets at fair value at beginning of period $ 2,013 $ 1,979 $ - $ - $ 1,208 $ 1,265  Actual return on plan assets 152 (36) - - 109 (29)  Company contribution 100 225 8 8 - 29  Actual benefits paid (164) (155) (8) (8) (53) (57)  Plan assets at fair value at end of period $ 2,101 $ 2,013 $ - $ - $ 1,264 $ 1,208  Funded status $ (461) 2 $ (390) 2 $ (151) $ (150) $ (144) $ (19)  Consumers  Benefit obligation at beginning of period $ 106 $ 111 $ 1,188 $ 1,336  Service cost - 1 17 25  Interest cost 4 4 45 56  Plan amendments - - - (24)  Actuarial (gain) loss 4 (5) 167 1 (150) 1  Benefits paid (5) (5) (52) (55)  Benefit obligation at end of period $ 109 $ 106 $ 1,365 $ 1,188  Plan assets at fair value at beginning of period $ - $ - $ 1,133 $ 1,186  Actual return on plan assets - - 103 (27)  Company contribution 5 5 - 29  Actual benefits paid (5) (5) (52) (55)  Plan assets at fair value at end of period $ - $ - $ 1,184 $ 1,133  Funded status $ (109) $ (106) $ (181) $ (55)  1 The actuarial loss for 2016 was primarily the result of claims, experience, and lowering the discount rates used in calculating the plans’ obligations. The actuarial gain for 2015 was primarily the result of increasing the discount rates used in calculating the plans’ obligations. 2 At December 31, 2016 , $ 441 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses. At December 31, 2015 , $ 368 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses. Presented in the following table is the classification of CMS Energy’s and Consumers’ retirement benefit plans’ liabilities:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  Current liabilities  DB SERP $ 8 $ 8  Non-current liabilities  DB Pension Plan 461 390  DB SERP 143 142  OPEB Plan 144 19  Consumers  Current liabilities  DB SERP $ 5 $ 5  Non-current liabilities  DB Pension Plan 441 368  DB SERP 104 101  OPEB Plan 181 55  Presented in the following table are the DB Pension Plan PBO, ABO, and fair value of plan assets:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  DB Pension Plan PBO $ 2,562 $ 2,403  DB Pension Plan ABO 2,250 2,140  Fair value of DB Pension Plan assets 2,101 2,013  Items Not Yet Recognized as a Component of Net Periodic Benefit Cost: Presented in the following table are the amounts recognized in regulatory assets and AOCI that have not been recognized as components of net periodic benefit cost. For additional details on regulatory assets and liabilities, see Note 3, Regulatory Matters.    In Millions  DB Pension Plan and DB SERP OPEB Plan  Years Ended December 31 2016 2015 2016 2015  CMS Energy, including Consumers  Regulatory assets  Net loss $ 1,062 $ 944 $ 483 $ 360  Prior service cost (credit) 15 19 (187) (227)  Regulatory assets $ 1,077 $ 963 $ 296 $ 133  AOCI  Net loss (gain) 93 86 (8) (11)  Prior service cost (credit) 1 1 (6) (8)  Total amounts recognized in regulatory assets and AOCI $ 1,171 $ 1,050 $ 282 $ 114  Consumers  Regulatory assets  Net loss $ 1,062 $ 944 $ 483 $ 360  Prior service cost (credit) 15 19 (187) (227)  Regulatory assets $ 1,077 $ 963 $ 296 $ 133  AOCI  Net loss 33 29 - -  Total amounts recognized in regulatory assets and AOCI $ 1,110 $ 992 $ 296 $ 133  Plan Assets: Presented in the following tables are the fair values of CMS Energy’s DB Pension Plan and OPEB Plan assets, by asset category and by level within the fair value hierarchy. For additional details regarding the fair value hierarchy, see Note 6, Fair Value Measurements.    In Millions  DB Pension Plan  December 31, 2016 December 31, 2015  Total Level 1 Level 2 Total Level 1 Level 2  CMS Energy, including Consumers  Cash and short-term investments $ 110 $ 110 $ - $ 215 $ 215 $ -  U.S. government and agencies securities 1 - 1 19 - 19  Corporate debt 266 - 266 243 - 243  State and municipal bonds 9 - 9 8 - 8  Foreign corporate bonds 25 - 25 16 - 16  Mutual funds 571 571 - 538 538 -  $ 982 $ 681 $ 301 $ 1,039 $ 753 $ 286  Pooled funds 1,119 974  Total $ 2,101 $ 2,013     In Millions  OPEB Plan  December 31, 2016 December 31, 2015  Total Level 1 Level 2 Total Level 1 Level 2  CMS Energy, including Consumers  Cash and short-term investments $ 39 $ 39 $ - $ 51 $ 51 $ -  U.S. government and agencies securities - - - 3 - 3  Corporate debt 38 - 38 34 - 34  State and municipal bonds 1 - 1 1 - 1  Foreign corporate bonds 4 - 4 2 - 2  Common stocks 44 44 - 54 54 -  Mutual funds 563 563 - 456 456 -  $ 689 $ 646 $ 43 $ 601 $ 561 $ 40  Pooled funds 575 607  Total $ 1,264 $ 1,208  Cash and Short-Term Investments: Cash and short-term investments consist of money market funds with daily liquidity. U.S. Government and Agencies Securities: U.S. government and agencies securities consist of U.S. Treasury notes and other debt securities backed by the U.S. government and related agencies. These securities were valued based on quoted market prices. Corporate Debt: Corporate debt investments consisted of investment grade bonds of U.S. issuers from diverse industries. These securities are valued based on quoted market prices, when available, or yields presently available on comparable securities of issuers with similar credit ratings. State and Municipal Bonds: State and municipal bonds were valued using a matrix-pricing model that incorporates Level 2 market-based information. The fair value of the bonds was derived from various observable inputs, including benchmark yields, reported securities trades, broker/dealer quotes, bond ratings, and general information on market movements for investment grade state and municipal securities normally considered by market participants when pricing such debt securities. Foreign Corporate Bonds: Foreign corporate debt securities were valued based on quoted market prices, when available, or on yields available on comparable securities of issuers with similar credit ratings. Common Stocks: Common stocks in the OPEB Plan consist of equity securities with low transaction costs that were actively managed and tracked by the S&P 500 Index. These securities were valued at their quoted closing prices. Mutual Funds: Mutual funds represent shares in registered investment companies that are priced based on the daily quoted NAVs that are publicly available and are the basis for transactions to buy or sell shares in the funds. Pooled Funds: Pooled funds include both common and collective trust funds as well as special funds that contain only employee benefit plan assets from two or more unrelated benefit plans. Presented in the following table are the investment components of these funds:    DB Pension Plan OPEB Plan  December 31 2016 2015 2016 2015  U.S. equity securities 67 % 62 % 72 % 58 %  Foreign equity securities 16 18 13 13  U.S. fixed-income securities 9 11 8 22  Foreign fixed-income securities 4 6 4 5  Alternative investments 4 3 3 2  100 % 100 % 100 % 100 %  Since these investments were valued at their NAV as a practical expedient, they are not classified in the fair value hierarchy. Target Asset Allocations: CMS Energy’s target asset allocation for DB Pension Plan assets is 53 percent equity, 32 percent fixed income, and 15 percent alternative-strategy investments. This target asset allocation is expected to continue to maximize the long-term return on plan assets, while maintaining a prudent level of risk. The level of acceptable risk is a function of the liabilities of the plan. Equity investments are diversified mostly across the S&P 500 Index, with lesser allocations to the S&P MidCap and SmallCap Indexes and Foreign Equity Funds. Fixed-income investments are diversified across investment grade instruments of government and corporate issuers as well as high-yield and global bond funds. Alternative strategies are diversified across absolute return investment approaches and global tactical asset allocation. CMS Energy use s annual liability measurements, quarterly portfolio reviews, and periodic asset/liability studies to evaluate the need for adjustments to the portfolio allocation. CMS Energy established union and non ‑union VEBA trusts to fund future retiree health and life insurance benefits. These trusts are funded through the ratemaking process for Consumers and through direct contributions from the non ‑utility subsidiaries. CMS Energy’s target asset allocation for the health trusts is 50 percent equity, 30 percent fixed income, and 20 percent alternative - strategy investments. CMS Energy’s target asset allocation for the life trusts is 42 percent equity, 28 percent fixed income, and 30 percent alternative - strategy investments . These target allocations are expected to continue to maximize the long-term return on plan assets, while maintaining a prudent level of risk. The level of acceptable risk is a function of the liabilities of the plan s . Equity investments are diversified mostly across the S&P 500 Index, with lesser allocations to the S&P SmallCap Index and Foreign Equity Funds. Fixed-income investments are diversified across investment grade instruments of government and corporate issuers. Alternative strategies are diversified across absolute return investment approaches and global tactical asset allocation. CMS Energy use s annual liability measurements, quarterly portfolio reviews, and periodic asset/liability studies to evaluate the need for adjustments to the portfolio allocation. Contributions: Presented in the following table are the contributions to CMS Energy’s and Consumers’ OPEB Plan and DB Pension Plan:    In Millions  Years Ended December 31 2016 2015  CMS Energy, including Consumers  OPEB Plan $ - $ 29  DB Pension Plan 100 225  Consumers  OPEB Plan $ - $ 29  DB Pension Plan 93 209  Contributions comprise required amounts and discretionary contributions. Neither CMS Energy nor Consumers plans to contribute to the OPEB or DB Pension Plans in 2017. Actual future contributions will depend on future investment performance, discount rates, and various factors related to the DB Pension Plan and OPEB Plan participants. Following amendments to the OPEB Plan in July 2013, Consumers’ OPEB costs decreased substantially and, as a result, the OPEB Plan was fully funded at December 31, 2013. In May 2014, Consumers filed an application with the MPSC requesting approval to suspend contributions to Consumers’ OPEB Plan during 2014 and 2015 if the OPEB Plan continued to be fully funded. Consumers’ electric and gas rates still reflect the higher OPEB costs, and previous MPSC orders required Consumers to contribute to the OPEB Plan the associated amount collected in rates annually. In September 2014, the MPSC approved a settlement agreement addressing Consumers’ OPEB Plan funding application. Under the settlement agreement, Consumers contributed $ 25 million to the plan in 2014 and $ 29 million in February 2015. Consumers will suspend further contributions until the MPSC determines funding requirements in future general rate cases. Benefit Payments: Presented in the following table are the expected benefit payments for each of the next five years and the five-year period thereafter:    In Millions  DB Pension Plan DB SERP OPEB Plan  CMS Energy, including Consumers  2017 $ 153 $ 8 $ 59  2018 159 8 63  2019 163 9 66  2020 165 11 69  2021 166 10 72  2022-2026 827 50 385  Consumers  2017 $ 149 $ 5 $ 57  2018 155 5 61  2019 159 6 64  2020 161 7 67  2021 161 7 70  2022-2026 803 32 371  Collective Bargaining Agreements: At December 31, 2016 , unions represented 39 percent of CMS Energy’s employees and 41 percent of Consumers’ employees. The UWUA represents Consumers’ operating, maintenance, construction, and call center employees. The USW represents Zeeland employees. Union contracts expire in 2020.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2016
Stock-Based Compensation	13: S tock -B ased C ompensation CMS Energy and Consumers provide a PISP to officers, employees, and non ‑employee directors based on their contributions to the successful management of the company. The PISP has a ten -year term, expiring in May 2024. In 201 6 , all awards were in the form of restricted stock or restricted stock units. The PISP also allows for unrestricted common stock, stock options, stock appreciation rights, phantom shares, performance units, and incentive options, none of which was granted in 201 6 , 201 5 , or 201 4 . Shares awarded or subject to stock options, phantom shares, or performance units may not exceed 6.5 million shares from June 2014 through May 2024, nor may such awards to any recipient exceed 500,000 shares in any calendar year. CMS Energy and Consumers may issue awards of up to 4,983,931 shares of common stock under the PISP as of December 31, 20 16 . Shares for which payment or exercise is in cash, as well as shares that expire, terminate, or are cancelled or forfeited, may be awarded or granted again under the PISP. All awards under the PISP vest fully upon death. Upon a change of control of CMS Energy or termination under an officer separation agreement, the awards will vest in accordance with specific officer agreements. If stated in the award, for restricted stock recipients who terminate employment due to retirement or disability, a pro-rata portion of the award will vest upon termination, with any market-based award also contingent upon the outcome of the market condition and any performance-based award contingent upon the outcome of the performance condition. The pro-rata portion is equal to the portion of the service period served between the award grant date and the employee’s termination date. The remaining portion of the awards will be forfeited. All awards for directors vest fully upon r etirement. Restricted shares may be forfeited if employment terminates for any other reason or if the minimum service requirements are not met, as described in the award document. Restricted Stock Awards: Restricted stock awards for employees under the PISP are in the form of performance-based, market-based, a nd time-lapse restricted stock. Award recipients receive shares of CMS Energy common stock that have dividend and voting rights. The dividends on time-lapse restricted stock are paid in cash or in CMS Energy common stock. T he dividends on performance-based and market-based restricted stock are paid in restricted shares equal to the value of the dividends. These additional restricted shares are subject to the same vesting conditions as the underlying restricted stock shares. Performance-based restricted stock vesting is contingent on meeting at least a 36 ‑month service requirement and a performance condition. The performance condition is based on an adjusted measure of CMS Energy’s EPS growth relative to a peer group over a three -year period. The awards granted in 201 6, 2015, and 2014 require a 38 ‑month service period. Market-based restricted stock vesting is generally contingent on meeting a three -year service requirement and a market condition. The market condition is based on a comparison of CMS Energy’s total shareholder return with the median total shareholder return of a peer group over the same three -year period. Depending on the outcome of the performance condition or the market condition, a recipient may earn a total award ranging from zero to 200 percent of the initial grant. Time-lapse restricted stock generally vests after a service period of three years. Restricted Stock Units: In 201 6 and 2015 , CMS Energy and Consumers granted restricted stock units to certain non ‑ employee directors who elected to defer their restricted stock awards. The restricted stock units generally vest after a service period of one year or, if earlier, at the next annual meeting. The restricted stock units will be distributed to the recipients as shares in accordance with the directors’ deferral agreements. Restricted stock units do not have voting rights, but do have dividend rights. In lieu of cash dividend payments, the dividends on restricted stock units are paid in additional units equal to the value of the dividends. These additional restricted stock units are subject to the same vesting and distribution conditions as the underlying restricted stock units. No restricted stock units were forfeited during 2016 . Presented in the following tables is the activity for restricted stock and restricted stock units under the 2009 and 2014 PISPs:    CMS Energy, including Consumers Consumers  Year Ended December 31, 2016 Number of Shares Weighted-Average Grant Date Fair Value per Share Number of Shares Weighted-Average Grant Date Fair Value per Share  Nonvested at beginning of period 1,624,934 $ 29.08 1,557,657 $ 29.06  Granted  Restricted stock 826,075 31.74 786,328 31.77  Restricted stock units 15,338 39.12 14,907 39.12  Vested  Restricted stock (819,658) 24.37 (782,505) 24.39  Restricted stock units (13,588) 33.22 (13,233) 33.23  Forfeited - restricted stock (245,504) 35.18 (234,523) 35.17  Nonvested at end of period 1,387,597 $ 32.44 1,328,631 $ 32.41     Year Ended December 31, 2016 CMS Energy, including Consumers Consumers  Granted  Time-lapse awards 188,303 180,958  Market-based awards 185,464 175,818  Performance-based awards 185,464 175,818  Restricted stock units 14,595 14,186  Dividends on market-based awards 38,652 36,646  Dividends on performance-based awards 14,438 13,704  Dividends on restricted stock units 743 721  Additional market-based shares based on achievement of condition 213,754 203,384  Total granted 841,413 801,235  CMS Energy and Consumers charge the fair value of the restricted stock awards to expense over the required service period and charge the fair value of the restricted stock units to expense immediately. For performance-based awards, CMS Energy and Consumers estimate the number of shares expected to vest at the end of the performance period based on the probable achievement of the performance objective. Performance-based and market-based restricted stock awards have graded vesting features for retirement-eligible employees, and CMS Energy and Consumers recognize expense for those awards on a graded vesting schedule over the required service period. Expense for performance-based and market-based restricted stock awards for non ‑retirement-eligible employees and time-lapse awards is recognized on a straight-line basis over the required service period. The fair value of performance-based and time-lapse restricted stock and restricted stock units is based on the price of CMS Energy’s common stock on the grant date. The fair value of market-based restricted stock awards is calculated on the grant date using a Monte Carlo simulation. CMS Energy and Consumers base expected volatilities on the historical volatility of the price of CMS Energy common stock. The risk-free rate for valuation of the market-based restricted stock awards was based on the three-year U.S. Treasury yield at the award grant date. Presented in the following table are the most important assumptions used to estimate the fair value of the market-based restricted stock awards:    Years Ended December 31 2016 2015 2014  Expected volatility 16.7 % 14.1 % 15.6 %  Expected dividend yield 3.2 3.3 3.7  Risk-free rate 1.0 0.8 0.8  Presented in the following table is the weighted-average grant-date fair value of all awards under the PISP:    Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Weighted-average grant-date fair value per share  Restricted stock granted $ 31.74 $ 36.84 $ 26.15  Restricted stock units granted 39.12 34.25 -  Consumers  Weighted-average grant-date fair value per share  Restricted stock granted $ 31.77 $ 36.83 $ 26.18  Restricted stock units granted 39.12 34.25 -  Presented in the following table are amounts related to restricted stock awards and restricted stock units:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Fair value of shares that vested during the year $ 31 $ 29 $ 16  Compensation expense recognized 16 20 14  Income tax benefit recognized 7 8 5  Consumers  Fair value of shares that vested during the year $ 30 $ 28 $ 15  Compensation expense recognized 16 19 13  Income tax benefit recognized 6 7 5  At December 31, 20 16 , $ 15 million of total unrecognized compensation cost was related to restricted stock for CMS Energy, including Consumers, and $ 14 million of total unrecognized compensation cost was related to restricted stock for Consumers. CMS Energy and Consumers expect to recognize this cost over a weighted-average period of 1.8 years.
Consumers Energy Company [Member]
Stock-Based Compensation	13: S tock -B ased C ompensation CMS Energy and Consumers provide a PISP to officers, employees, and non ‑employee directors based on their contributions to the successful management of the company. The PISP has a ten -year term, expiring in May 2024. In 201 6 , all awards were in the form of restricted stock or restricted stock units. The PISP also allows for unrestricted common stock, stock options, stock appreciation rights, phantom shares, performance units, and incentive options, none of which was granted in 201 6 , 201 5 , or 201 4 . Shares awarded or subject to stock options, phantom shares, or performance units may not exceed 6.5 million shares from June 2014 through May 2024, nor may such awards to any recipient exceed 500,000 shares in any calendar year. CMS Energy and Consumers may issue awards of up to 4,983,931 shares of common stock under the PISP as of December 31, 20 16 . Shares for which payment or exercise is in cash, as well as shares that expire, terminate, or are cancelled or forfeited, may be awarded or granted again under the PISP. All awards under the PISP vest fully upon death. Upon a change of control of CMS Energy or termination under an officer separation agreement, the awards will vest in accordance with specific officer agreements. If stated in the award, for restricted stock recipients who terminate employment due to retirement or disability, a pro-rata portion of the award will vest upon termination, with any market-based award also contingent upon the outcome of the market condition and any performance-based award contingent upon the outcome of the performance condition. The pro-rata portion is equal to the portion of the service period served between the award grant date and the employee’s termination date. The remaining portion of the awards will be forfeited. All awards for directors vest fully upon r etirement. Restricted shares may be forfeited if employment terminates for any other reason or if the minimum service requirements are not met, as described in the award document. Restricted Stock Awards: Restricted stock awards for employees under the PISP are in the form of performance-based, market-based, a nd time-lapse restricted stock. Award recipients receive shares of CMS Energy common stock that have dividend and voting rights. The dividends on time-lapse restricted stock are paid in cash or in CMS Energy common stock. T he dividends on performance-based and market-based restricted stock are paid in restricted shares equal to the value of the dividends. These additional restricted shares are subject to the same vesting conditions as the underlying restricted stock shares. Performance-based restricted stock vesting is contingent on meeting at least a 36 ‑month service requirement and a performance condition. The performance condition is based on an adjusted measure of CMS Energy’s EPS growth relative to a peer group over a three -year period. The awards granted in 201 6, 2015, and 2014 require a 38 ‑month service period. Market-based restricted stock vesting is generally contingent on meeting a three -year service requirement and a market condition. The market condition is based on a comparison of CMS Energy’s total shareholder return with the median total shareholder return of a peer group over the same three -year period. Depending on the outcome of the performance condition or the market condition, a recipient may earn a total award ranging from zero to 200 percent of the initial grant. Time-lapse restricted stock generally vests after a service period of three years. Restricted Stock Units: In 201 6 and 2015 , CMS Energy and Consumers granted restricted stock units to certain non ‑ employee directors who elected to defer their restricted stock awards. The restricted stock units generally vest after a service period of one year or, if earlier, at the next annual meeting. The restricted stock units will be distributed to the recipients as shares in accordance with the directors’ deferral agreements. Restricted stock units do not have voting rights, but do have dividend rights. In lieu of cash dividend payments, the dividends on restricted stock units are paid in additional units equal to the value of the dividends. These additional restricted stock units are subject to the same vesting and distribution conditions as the underlying restricted stock units. No restricted stock units were forfeited during 2016 . Presented in the following tables is the activity for restricted stock and restricted stock units under the 2009 and 2014 PISPs:    CMS Energy, including Consumers Consumers  Year Ended December 31, 2016 Number of Shares Weighted-Average Grant Date Fair Value per Share Number of Shares Weighted-Average Grant Date Fair Value per Share  Nonvested at beginning of period 1,624,934 $ 29.08 1,557,657 $ 29.06  Granted  Restricted stock 826,075 31.74 786,328 31.77  Restricted stock units 15,338 39.12 14,907 39.12  Vested  Restricted stock (819,658) 24.37 (782,505) 24.39  Restricted stock units (13,588) 33.22 (13,233) 33.23  Forfeited - restricted stock (245,504) 35.18 (234,523) 35.17  Nonvested at end of period 1,387,597 $ 32.44 1,328,631 $ 32.41     Year Ended December 31, 2016 CMS Energy, including Consumers Consumers  Granted  Time-lapse awards 188,303 180,958  Market-based awards 185,464 175,818  Performance-based awards 185,464 175,818  Restricted stock units 14,595 14,186  Dividends on market-based awards 38,652 36,646  Dividends on performance-based awards 14,438 13,704  Dividends on restricted stock units 743 721  Additional market-based shares based on achievement of condition 213,754 203,384  Total granted 841,413 801,235  CMS Energy and Consumers charge the fair value of the restricted stock awards to expense over the required service period and charge the fair value of the restricted stock units to expense immediately. For performance-based awards, CMS Energy and Consumers estimate the number of shares expected to vest at the end of the performance period based on the probable achievement of the performance objective. Performance-based and market-based restricted stock awards have graded vesting features for retirement-eligible employees, and CMS Energy and Consumers recognize expense for those awards on a graded vesting schedule over the required service period. Expense for performance-based and market-based restricted stock awards for non ‑retirement-eligible employees and time-lapse awards is recognized on a straight-line basis over the required service period. The fair value of performance-based and time-lapse restricted stock and restricted stock units is based on the price of CMS Energy’s common stock on the grant date. The fair value of market-based restricted stock awards is calculated on the grant date using a Monte Carlo simulation. CMS Energy and Consumers base expected volatilities on the historical volatility of the price of CMS Energy common stock. The risk-free rate for valuation of the market-based restricted stock awards was based on the three-year U.S. Treasury yield at the award grant date. Presented in the following table are the most important assumptions used to estimate the fair value of the market-based restricted stock awards:    Years Ended December 31 2016 2015 2014  Expected volatility 16.7 % 14.1 % 15.6 %  Expected dividend yield 3.2 3.3 3.7  Risk-free rate 1.0 0.8 0.8  Presented in the following table is the weighted-average grant-date fair value of all awards under the PISP:    Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Weighted-average grant-date fair value per share  Restricted stock granted $ 31.74 $ 36.84 $ 26.15  Restricted stock units granted 39.12 34.25 -  Consumers  Weighted-average grant-date fair value per share  Restricted stock granted $ 31.77 $ 36.83 $ 26.18  Restricted stock units granted 39.12 34.25 -  Presented in the following table are amounts related to restricted stock awards and restricted stock units:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Fair value of shares that vested during the year $ 31 $ 29 $ 16  Compensation expense recognized 16 20 14  Income tax benefit recognized 7 8 5  Consumers  Fair value of shares that vested during the year $ 30 $ 28 $ 15  Compensation expense recognized 16 19 13  Income tax benefit recognized 6 7 5  At December 31, 20 16 , $ 15 million of total unrecognized compensation cost was related to restricted stock for CMS Energy, including Consumers, and $ 14 million of total unrecognized compensation cost was related to restricted stock for Consumers. CMS Energy and Consumers expect to recognize this cost over a weighted-average period of 1.8 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Taxes	14: I ncome T axes CMS Energy and its subsidiaries file a consolidated U.S. federal income tax return and a unitary Michigan income tax return. Income taxes are allocated based on each company’s separate taxable income in accordance with the CMS Energy tax sharing agreement. Presented in the following table is the difference between actual income tax expense on continuing operations and income tax expense computed by applying the statutory U.S. federal income tax rate:    In Millions, Except Tax Rate  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Income from continuing operations before income taxes $ 826 $ 796 $ 729   Income tax expense at statutory rate 289 279 255  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 37 39 36  Accelerated flow-through of regulatory tax benefits 1 (39) (39) (39)  Employee share-based awards 2 (7) - -  Other, net (7) (8) (2)  Income tax expense $ 273 $ 271 $ 250  Effective tax rate 33.1 % 34.0 % 34.3 %  Consumers  Income from continuing operations before income taxes $ 936 $ 896 $ 873   Income tax expense at statutory rate 328 314 306  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 44 42 42  Accelerated flow-through of regulatory tax benefits 1 (39) (39) (39)  Employee share-based awards 2 (6) - -  Other, net (7) (15) (3)  Income tax expense $ 320 $ 302 $ 306  Effective tax rate 34.2 % 33.7 % 35.1 %  1 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 $ 39 million for each of the years ended December 31, 2016 , 2015 , and 2014. 2 CMS Energy and Consumers elected to adopt ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , as of January 1, 2016. For further details on the implementation of this standard, see Note 2, New Accounting Standards. Presented in the following table are the significant components of income tax expense on continuing operations:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Current income taxes  Federal $ - $ - $ -  State and local 9 24 24  $ 9 $ 24 $ 24  Deferred income taxes  Federal $ 200 $ 192 $ 198  State and local 47 36 31  $ 247 $ 228 $ 229  Deferred income tax credit 17 19 (3)  Tax expense $ 273 $ 271 $ 250  Consumers  Current income taxes  Federal $ 9 $ 66 $ 8  State and local 22 32 36  $ 31 $ 98 $ 44  Deferred income taxes  Federal $ 227 $ 153 $ 236  State and local 45 32 29  $ 272 $ 185 $ 265  Deferred income tax credit 17 19 (3)  Tax expense $ 320 $ 302 $ 306  Presented in the following table are the principal components of deferred income tax assets (liabilities) recognized:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  Employee benefits $ (158) $ (127)  Gas inventory (65) (96)  Plant, property, and equipment (2,902) (2,429)  Net regulatory tax liability 27 50  Reserves and accruals 69 59  Securitized costs (118) (122)  Tax loss and credit carryforwards 871 657  Other (6) (5)  $ (2,282) $ (2,013)  Less valuation allowance (5) (4)  Total net deferred income tax liabilities $ (2,287) $ (2,017)  Deferred tax assets, net of valuation reserves $ 962 $ 762  Deferred tax liabilities (3,249) (2,779)  Total net deferred income tax liabilities $ (2,287) $ (2,017)  Consumers  Employee benefits $ (181) $ (156)  Gas inventory (65) (96)  Plant, property, and equipment (2,924) (2,457)  Net regulatory tax liability 27 50  Reserves and accruals 37 30  Securitized costs (118) (122)  Tax loss and credit carryforwards 190 46  Other (8) (5)  Total net deferred income tax liabilities $ (3,042) $ (2,710)  Deferred tax assets, net of valuation reserves $ 254 $ 126  Deferred tax liabilities (3,296) (2,836)  Total net deferred income tax liabilities $ (3,042) $ (2,710)  Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts on CMS Energy’s and Consumers’ co nsolidated financial statements . Presented in the following table are the tax loss and credit carryforwards at December 31, 20 16 :    In Millions  Gross Amount Tax Attribute Expiration  CMS Energy, including Consumers  Federal net operating loss carryforward $ 1,415 $ 495 2025 – 2036  Local net operating loss carryforwards 408 4 2023 – 2036  Alternative minimum tax credits 270 270 No expiration  General business credits 102 102 2018 – 2036  Total tax attributes $ 871  Consumers  Federal net operating loss carryforward $ 447 $ 157 2025 – 2036  General business credits 33 33 2032 – 2036  Total tax attributes $ 190  CMS Energy has provided a valuation allowance of $ 2 million for the local tax loss carryforward , and $3 million for general business credits . CMS Energy and Consumers expect to utilize fully tax loss and credit carryforwards for which no valuation allowance has been provided. It is reasonably possible that further adjustments will be made to the valuation allowances within one year. Presented in the following table is a reconciliation of the beginning and ending amount of uncertain tax benefits:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Balance at beginning of period $ 6 $ 5 $ 4  Additions for current-year tax positions - 1 2  Additions for prior-year tax positions - 1 1  Reductions for prior-year tax positions - (1) (2)  Settlements (1) - -  Balance at end of period $ 5 $ 6 $ 5  Consumers  Balance at beginning of period $ 6 $ 5 $ 4  Additions for current-year tax positions - 1 2  Additions for prior-year tax positions - 1 1  Reductions for prior-year tax positions - (1) (2)  Settlements (1) - -  Balance at end of period $ 5 $ 6 $ 5  If recognized, all of these uncertain tax benefits would affect CMS Energy’s and Consumers’ annual effective tax rates in fu ture years. CMS Energy and Consumers recognize accrued interest and penalties, where applicable, as part of income tax expense. CMS Energy, including Consumers, recognized no interest or penalties for the years ended December 31, 20 16 , 2015 , or 2014 . In April 2014, the IRS completed its audit of the federal income tax returns of CMS Energy and its subsidiaries for 2010 and 2011. The audit resulted in no significant adjustments to CMS Energy’s or Consumers’ taxable income or income tax expense. CMS Energy’s fed eral income tax returns for 2013 and subsequent years remain subject to examination by the IRS. CMS Energy’s M ichigan C orporate I ncome T ax and M ichigan B usiness T ax returns for 2008 and subsequent years remain subject to examination by the State of Michigan. The amount of income taxes paid is subject to ongoing audits by federal, state, local, and foreign tax authorities, which can result in proposed assessments. CMS Energy’s and Consumers’ estimate of the potential outcome for any uncertain tax issue is highly judgmental. CMS Energy and Consumers believe that their accrued tax liabilities at December 31, 20 16 were adequate for all years.
Consumers Energy Company [Member]
Income Taxes	14: I ncome T axes CMS Energy and its subsidiaries file a consolidated U.S. federal income tax return and a unitary Michigan income tax return. Income taxes are allocated based on each company’s separate taxable income in accordance with the CMS Energy tax sharing agreement. Presented in the following table is the difference between actual income tax expense on continuing operations and income tax expense computed by applying the statutory U.S. federal income tax rate:    In Millions, Except Tax Rate  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Income from continuing operations before income taxes $ 826 $ 796 $ 729   Income tax expense at statutory rate 289 279 255  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 37 39 36  Accelerated flow-through of regulatory tax benefits 1 (39) (39) (39)  Employee share-based awards 2 (7) - -  Other, net (7) (8) (2)  Income tax expense $ 273 $ 271 $ 250  Effective tax rate 33.1 % 34.0 % 34.3 %  Consumers  Income from continuing operations before income taxes $ 936 $ 896 $ 873   Income tax expense at statutory rate 328 314 306  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 44 42 42  Accelerated flow-through of regulatory tax benefits 1 (39) (39) (39)  Employee share-based awards 2 (6) - -  Other, net (7) (15) (3)  Income tax expense $ 320 $ 302 $ 306  Effective tax rate 34.2 % 33.7 % 35.1 %  1 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 $ 39 million for each of the years ended December 31, 2016 , 2015 , and 2014. 2 CMS Energy and Consumers elected to adopt ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , as of January 1, 2016. For further details on the implementation of this standard, see Note 2, New Accounting Standards. Presented in the following table are the significant components of income tax expense on continuing operations:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Current income taxes  Federal $ - $ - $ -  State and local 9 24 24  $ 9 $ 24 $ 24  Deferred income taxes  Federal $ 200 $ 192 $ 198  State and local 47 36 31  $ 247 $ 228 $ 229  Deferred income tax credit 17 19 (3)  Tax expense $ 273 $ 271 $ 250  Consumers  Current income taxes  Federal $ 9 $ 66 $ 8  State and local 22 32 36  $ 31 $ 98 $ 44  Deferred income taxes  Federal $ 227 $ 153 $ 236  State and local 45 32 29  $ 272 $ 185 $ 265  Deferred income tax credit 17 19 (3)  Tax expense $ 320 $ 302 $ 306  Presented in the following table are the principal components of deferred income tax assets (liabilities) recognized:    In Millions  December 31 2016 2015  CMS Energy, including Consumers  Employee benefits $ (158) $ (127)  Gas inventory (65) (96)  Plant, property, and equipment (2,902) (2,429)  Net regulatory tax liability 27 50  Reserves and accruals 69 59  Securitized costs (118) (122)  Tax loss and credit carryforwards 871 657  Other (6) (5)  $ (2,282) $ (2,013)  Less valuation allowance (5) (4)  Total net deferred income tax liabilities $ (2,287) $ (2,017)  Deferred tax assets, net of valuation reserves $ 962 $ 762  Deferred tax liabilities (3,249) (2,779)  Total net deferred income tax liabilities $ (2,287) $ (2,017)  Consumers  Employee benefits $ (181) $ (156)  Gas inventory (65) (96)  Plant, property, and equipment (2,924) (2,457)  Net regulatory tax liability 27 50  Reserves and accruals 37 30  Securitized costs (118) (122)  Tax loss and credit carryforwards 190 46  Other (8) (5)  Total net deferred income tax liabilities $ (3,042) $ (2,710)  Deferred tax assets, net of valuation reserves $ 254 $ 126  Deferred tax liabilities (3,296) (2,836)  Total net deferred income tax liabilities $ (3,042) $ (2,710)  Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts on CMS Energy’s and Consumers’ co nsolidated financial statements . Presented in the following table are the tax loss and credit carryforwards at December 31, 20 16 :    In Millions  Gross Amount Tax Attribute Expiration  CMS Energy, including Consumers  Federal net operating loss carryforward $ 1,415 $ 495 2025 – 2036  Local net operating loss carryforwards 408 4 2023 – 2036  Alternative minimum tax credits 270 270 No expiration  General business credits 102 102 2018 – 2036  Total tax attributes $ 871  Consumers  Federal net operating loss carryforward $ 447 $ 157 2025 – 2036  General business credits 33 33 2032 – 2036  Total tax attributes $ 190  CMS Energy has provided a valuation allowance of $ 2 million for the local tax loss carryforward , and $3 million for general business credits . CMS Energy and Consumers expect to utilize fully tax loss and credit carryforwards for which no valuation allowance has been provided. It is reasonably possible that further adjustments will be made to the valuation allowances within one year. Presented in the following table is a reconciliation of the beginning and ending amount of uncertain tax benefits:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Balance at beginning of period $ 6 $ 5 $ 4  Additions for current-year tax positions - 1 2  Additions for prior-year tax positions - 1 1  Reductions for prior-year tax positions - (1) (2)  Settlements (1) - -  Balance at end of period $ 5 $ 6 $ 5  Consumers  Balance at beginning of period $ 6 $ 5 $ 4  Additions for current-year tax positions - 1 2  Additions for prior-year tax positions - 1 1  Reductions for prior-year tax positions - (1) (2)  Settlements (1) - -  Balance at end of period $ 5 $ 6 $ 5  If recognized, all of these uncertain tax benefits would affect CMS Energy’s and Consumers’ annual effective tax rates in fu ture years. CMS Energy and Consumers recognize accrued interest and penalties, where applicable, as part of income tax expense. CMS Energy, including Consumers, recognized no interest or penalties for the years ended December 31, 20 16 , 2015 , or 2014 . In April 2014, the IRS completed its audit of the federal income tax returns of CMS Energy and its subsidiaries for 2010 and 2011. The audit resulted in no significant adjustments to CMS Energy’s or Consumers’ taxable income or income tax expense. CMS Energy’s fed eral income tax returns for 2013 and subsequent years remain subject to examination by the IRS. CMS Energy’s M ichigan C orporate I ncome T ax and M ichigan B usiness T ax returns for 2008 and subsequent years remain subject to examination by the State of Michigan. The amount of income taxes paid is subject to ongoing audits by federal, state, local, and foreign tax authorities, which can result in proposed assessments. CMS Energy’s and Consumers’ estimate of the potential outcome for any uncertain tax issue is highly judgmental. CMS Energy and Consumers believe that their accrued tax liabilities at December 31, 20 16 were adequate for all years.

Earnings Per Share - CMS Energy

Earnings Per Share - CMS Energy	12 Months Ended
	Dec. 31, 2016
Earnings Per Share - CMS Energy [Abstract]
Earnings Per Share - CMS Energy	15: E arnings P er S hare —CMS E nergy Presented in the following table are CMS Energy’s basic and diluted EPS computations based on net income:    In Millions, Except Per Share Amounts  Years Ended December 31 2016 2015 2014  Income available to common stockholders  Net income $ 553 $ 525 $ 479  Less income attributable to noncontrolling interests 2 2 2  Net income available to common stockholders – basic and diluted $ 551 $ 523 $ 477  Average common shares outstanding  Weighted-average shares – basic 277.9 275.6 270.6  Add dilutive contingently convertible securities - - 3.1  Add dilutive nonvested stock awards 1.0 0.9 0.9  Weighted-average shares – diluted 278.9 276.5 274.6  Net income per average common share available to common stockholders  Basic $ 1.99 $ 1.90 $ 1.76  Diluted 1.98 1.89 1.74   Dividends declared per common share $ 1.24 $ 1.16 $ 1.08  Contingently Convertible Securities In June 2014, CMS Energy redeemed its remaining contingently convertible securities. For the periods those securities were outstanding, they diluted EPS to the extent that the conversion value of the securities, which was based on the average market price of CMS Energy common stock, exceeded their principal value. Non vested Stock Awards CMS Energy’s non vested 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 recipi ent forfeits the award, the non vested stock awards are considered participating securities. As such, the participating non vested 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.

Other Income and Other Expense

Other Income and Other Expense	12 Months Ended
	Dec. 31, 2016
Other Income and Other Expense	16: O ther I ncome and O ther E xpense P resented in the following table are the components of other income and other expense at CMS Energy and Consumers:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Other income  Fee income $ 6 $ 9 $ 8  All other 2 1 3  Total other income – CMS Energy $ 8 $ 10 $ 11  Consumers  Other income  Fee income $ 6 $ 9 $ 8  Gain on CMS Energy common stock - 9 -  All other 2 1 2  Total other income – Consumers $ 8 $ 19 $ 10  CMS Energy, including Consumers  Other expense  Civic and political expenditures $ (21) $ (10) $ (14)  Donations (23) (1) (15)  Loss on reacquired and extinguished debt (18) - (20)  Unrealized investment loss (5) - -  All other (8) (6) (6)  Total other expense – CMS Energy $ (75) $ (17) $ (55)  Consumers  Other expense  Civic and political expenditures $ (21) $ (10) $ (14)  Donations (23) (1) (15)  Unrealized investment loss (4) - -  All other (7) (6) (6)  Total other expense – Consumers $ (55) $ (17) $ (35) 
Consumers Energy Company [Member]
Other Income and Other Expense	16: O ther I ncome and O ther E xpense P resented in the following table are the components of other income and other expense at CMS Energy and Consumers:    In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Other income  Fee income $ 6 $ 9 $ 8  All other 2 1 3  Total other income – CMS Energy $ 8 $ 10 $ 11  Consumers  Other income  Fee income $ 6 $ 9 $ 8  Gain on CMS Energy common stock - 9 -  All other 2 1 2  Total other income – Consumers $ 8 $ 19 $ 10  CMS Energy, including Consumers  Other expense  Civic and political expenditures $ (21) $ (10) $ (14)  Donations (23) (1) (15)  Loss on reacquired and extinguished debt (18) - (20)  Unrealized investment loss (5) - -  All other (8) (6) (6)  Total other expense – CMS Energy $ (75) $ (17) $ (55)  Consumers  Other expense  Civic and political expenditures $ (21) $ (10) $ (14)  Donations (23) (1) (15)  Unrealized investment loss (4) - -  All other (7) (6) (6)  Total other expense – Consumers $ (55) $ (17) $ (35) 

Cash And Cash Equivalents

Cash And Cash Equivalents	12 Months Ended
	Dec. 31, 2016
Cash And Cash Equivalents	17: 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  December 31 2016 2015  CMS Energy, including Consumers  Cash and cash equivalents $ 235 $ 266  Restricted cash and cash equivalents 19 19  Other non-current assets 3 3  Cash and cash equivalents, including restricted amounts $ 257 $ 288  Consumers  Cash and cash equivalents $ 131 $ 50  Restricted cash and cash equivalents 19 19  Other non-current assets 2 2  Cash and cash equivalents, including restricted amounts $ 152 $ 71  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-Current Assets: The majority of 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 6, Fair Value Measurements and Note 12, Retirement Benefits for more information regarding the DB SERP.
Consumers Energy Company [Member]
Cash And Cash Equivalents	17: 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  December 31 2016 2015  CMS Energy, including Consumers  Cash and cash equivalents $ 235 $ 266  Restricted cash and cash equivalents 19 19  Other non-current assets 3 3  Cash and cash equivalents, including restricted amounts $ 257 $ 288  Consumers  Cash and cash equivalents $ 131 $ 50  Restricted cash and cash equivalents 19 19  Other non-current assets 2 2  Cash and cash equivalents, including restricted amounts $ 152 $ 71  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-Current Assets: The majority of 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 6, Fair Value Measurements and Note 12, Retirement Benefits for more information regarding the DB SERP.

Reportable Segments

Reportable Segments	12 Months Ended
	Dec. 31, 2016
Reportable Segments	18 : R eportable 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. Accounting policies for CMS Energy’s and Consumers’ segments are as described in Note 1, Significant Accounting Policies. The consolidated financial statements reflect the assets, liabilities, revenues, and expenses of the individual segments when appropriate. Accounts are allocated among the segments when common accounts are attributable to more than one segment. The allocations are based on certain measures of business activities, such as revenue, labor dollars, customers, other operation and maintenance expense, construction expense, leased property, taxes, or functional surveys. For example, customer receivables are allocated based on revenue, and pension provisions are allocated based on labor dollars. Inter-segment sales and transfers are accounted for at current market prices and are eliminated in consolidated net income available to common stockholders by segment. 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 product ion 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 distribu tion 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  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Operating revenue  Electric utility $ 4,379 $ 4,249 $ 4,436  Gas utility 1,685 1,916 2,363  Enterprises 215 190 299  Other reconciling items 120 101 81  Total operating revenue – CMS Energy $ 6,399 $ 6,456 $ 7,179  Consumers  Operating revenue  Electric utility $ 4,379 $ 4,249 $ 4,436  Gas utility 1,685 1,916 2,363  Other reconciling items - - 1  Total operating revenue – Consumers $ 6,064 $ 6,165 $ 6,800  CMS Energy, including Consumers  Depreciation and amortization  Electric utility $ 603 $ 567 $ 522  Gas utility 200 177 156  Enterprises 5 4 4  Other reconciling items 3 2 3  Total depreciation and amortization – CMS Energy $ 811 $ 750 $ 685  Consumers  Depreciation and amortization  Electric utility $ 603 $ 567 $ 522  Gas utility 200 177 156  Total depreciation and amortization – Consumers $ 803 $ 744 $ 678  CMS Energy, including Consumers  Income from equity method investees 1  Enterprises $ 13 $ 14 $ 15  Total income from equity method investees – CMS Energy $ 13 $ 14 $ 15  CMS Energy, including Consumers  Interest charges  Electric utility $ 196 $ 178 $ 181  Gas utility 72 71 67  Enterprises 1 - -  Other reconciling items 166 147 159  Total interest charges – CMS Energy $ 435 $ 396 $ 407  Consumers  Interest charges  Electric utility $ 196 $ 178 $ 181  Gas utility 72 71 67  Other reconciling items - 1 2  Total interest charges – Consumers $ 268 $ 250 $ 250     In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Income tax expense (benefit)  Electric utility $ 246 $ 224 $ 211  Gas utility 74 78 95  Enterprises 10 3 (1)  Other reconciling items (57) (34) (55)  Total income tax expense – CMS Energy $ 273 $ 271 $ 250  Consumers  Income tax expense  Electric utility $ 246 $ 224 $ 211  Gas utility 74 78 95  Total income tax expense – Consumers $ 320 $ 302 $ 306  CMS Energy, including Consumers  Net income (loss) available to common stockholders  Electric utility $ 458 $ 437 $ 384  Gas utility 155 154 179  Enterprises 17 4 (1)  Other reconciling items (79) (72) (85)  Total net income available to common stockholders – CMS Energy $ 551 $ 523 $ 477  Consumers  Net income available to common stockholder  Electric utility $ 458 $ 437 $ 384  Gas utility 155 154 179  Other reconciling items 1 1 2  Total net income available to common stockholder – Consumers $ 614 $ 592 $ 565  CMS Energy, including Consumers  Plant, property, and equipment, gross  Electric utility $ 14,540 $ 13,059 $ 12,230  Gas utility 6,283 5,723 5,335  Enterprises 157 120 115  Other reconciling items 30 41 41  Total plant, property, and equipment, gross – CMS Energy $ 21,010 $ 18,943 $ 17,721  Consumers  Plant, property, and equipment, gross  Electric utility $ 14,540 $ 13,059 $ 12,230  Gas utility 6,283 5,723 5,335  Other reconciling items 15 15 15  Total plant, property, and equipment, gross – Consumers $ 20,838 $ 18,797 $ 17,580  CMS Energy, including Consumers  Investments in equity method investees 1  Enterprises $ 62 $ 61 $ 58  Other reconciling items 3 3 3  Total investments in equity method investees – CMS Energy $ 65 $ 64 $ 61     In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Total assets  Electric utility 2 $ 13,429 $ 12,660 $ 11,565  Gas utility 2 6,446 5,912 5,385  Enterprises 269 270 231  Other reconciling items 1,478 1,457 1,962  Total assets – CMS Energy $ 21,622 $ 20,299 $ 19,143  Consumers  Total assets  Electric utility 2 $ 13,430 $ 12,660 $ 11,565  Gas utility 2 6,446 5,912 5,385  Other reconciling items 70 63 874  Total assets – Consumers $ 19,946 $ 18,635 $ 17,824  CMS Energy, including Consumers  Capital expenditures 3  Electric utility $ 1,007 $ 1,136 $ 1,139  Gas utility 611 558 473  Enterprises 10 44 3  Other reconciling items 5 3 1  Total capital expenditures – CMS Energy $ 1,633 $ 1,741 $ 1,616  Consumers  Capital expenditures 3  Electric utility $ 1,007 $ 1,136 $ 1,139  Gas utility 611 558 473  Total capital expenditures – Consumers $ 1,618 $ 1,694 $ 1,612  1 Consumers had no significant equity method investments. 2 Amounts include a portion of Consumers’ other common assets attributable to both the electric and gas utility businesses. 3 Amounts include purchase of capital lease additions. Amounts also include a portion of Consumers’ capital expenditures for plant and equipment attributable to both the electric and gas utility businesses.
Consumers Energy Company [Member]
Reportable Segments	18 : R eportable 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. Accounting policies for CMS Energy’s and Consumers’ segments are as described in Note 1, Significant Accounting Policies. The consolidated financial statements reflect the assets, liabilities, revenues, and expenses of the individual segments when appropriate. Accounts are allocated among the segments when common accounts are attributable to more than one segment. The allocations are based on certain measures of business activities, such as revenue, labor dollars, customers, other operation and maintenance expense, construction expense, leased property, taxes, or functional surveys. For example, customer receivables are allocated based on revenue, and pension provisions are allocated based on labor dollars. Inter-segment sales and transfers are accounted for at current market prices and are eliminated in consolidated net income available to common stockholders by segment. 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 product ion 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 distribu tion 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  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Operating revenue  Electric utility $ 4,379 $ 4,249 $ 4,436  Gas utility 1,685 1,916 2,363  Enterprises 215 190 299  Other reconciling items 120 101 81  Total operating revenue – CMS Energy $ 6,399 $ 6,456 $ 7,179  Consumers  Operating revenue  Electric utility $ 4,379 $ 4,249 $ 4,436  Gas utility 1,685 1,916 2,363  Other reconciling items - - 1  Total operating revenue – Consumers $ 6,064 $ 6,165 $ 6,800  CMS Energy, including Consumers  Depreciation and amortization  Electric utility $ 603 $ 567 $ 522  Gas utility 200 177 156  Enterprises 5 4 4  Other reconciling items 3 2 3  Total depreciation and amortization – CMS Energy $ 811 $ 750 $ 685  Consumers  Depreciation and amortization  Electric utility $ 603 $ 567 $ 522  Gas utility 200 177 156  Total depreciation and amortization – Consumers $ 803 $ 744 $ 678  CMS Energy, including Consumers  Income from equity method investees 1  Enterprises $ 13 $ 14 $ 15  Total income from equity method investees – CMS Energy $ 13 $ 14 $ 15  CMS Energy, including Consumers  Interest charges  Electric utility $ 196 $ 178 $ 181  Gas utility 72 71 67  Enterprises 1 - -  Other reconciling items 166 147 159  Total interest charges – CMS Energy $ 435 $ 396 $ 407  Consumers  Interest charges  Electric utility $ 196 $ 178 $ 181  Gas utility 72 71 67  Other reconciling items - 1 2  Total interest charges – Consumers $ 268 $ 250 $ 250     In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Income tax expense (benefit)  Electric utility $ 246 $ 224 $ 211  Gas utility 74 78 95  Enterprises 10 3 (1)  Other reconciling items (57) (34) (55)  Total income tax expense – CMS Energy $ 273 $ 271 $ 250  Consumers  Income tax expense  Electric utility $ 246 $ 224 $ 211  Gas utility 74 78 95  Total income tax expense – Consumers $ 320 $ 302 $ 306  CMS Energy, including Consumers  Net income (loss) available to common stockholders  Electric utility $ 458 $ 437 $ 384  Gas utility 155 154 179  Enterprises 17 4 (1)  Other reconciling items (79) (72) (85)  Total net income available to common stockholders – CMS Energy $ 551 $ 523 $ 477  Consumers  Net income available to common stockholder  Electric utility $ 458 $ 437 $ 384  Gas utility 155 154 179  Other reconciling items 1 1 2  Total net income available to common stockholder – Consumers $ 614 $ 592 $ 565  CMS Energy, including Consumers  Plant, property, and equipment, gross  Electric utility $ 14,540 $ 13,059 $ 12,230  Gas utility 6,283 5,723 5,335  Enterprises 157 120 115  Other reconciling items 30 41 41  Total plant, property, and equipment, gross – CMS Energy $ 21,010 $ 18,943 $ 17,721  Consumers  Plant, property, and equipment, gross  Electric utility $ 14,540 $ 13,059 $ 12,230  Gas utility 6,283 5,723 5,335  Other reconciling items 15 15 15  Total plant, property, and equipment, gross – Consumers $ 20,838 $ 18,797 $ 17,580  CMS Energy, including Consumers  Investments in equity method investees 1  Enterprises $ 62 $ 61 $ 58  Other reconciling items 3 3 3  Total investments in equity method investees – CMS Energy $ 65 $ 64 $ 61     In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Total assets  Electric utility 2 $ 13,429 $ 12,660 $ 11,565  Gas utility 2 6,446 5,912 5,385  Enterprises 269 270 231  Other reconciling items 1,478 1,457 1,962  Total assets – CMS Energy $ 21,622 $ 20,299 $ 19,143  Consumers  Total assets  Electric utility 2 $ 13,430 $ 12,660 $ 11,565  Gas utility 2 6,446 5,912 5,385  Other reconciling items 70 63 874  Total assets – Consumers $ 19,946 $ 18,635 $ 17,824  CMS Energy, including Consumers  Capital expenditures 3  Electric utility $ 1,007 $ 1,136 $ 1,139  Gas utility 611 558 473  Enterprises 10 44 3  Other reconciling items 5 3 1  Total capital expenditures – CMS Energy $ 1,633 $ 1,741 $ 1,616  Consumers  Capital expenditures 3  Electric utility $ 1,007 $ 1,136 $ 1,139  Gas utility 611 558 473  Total capital expenditures – Consumers $ 1,618 $ 1,694 $ 1,612  1 Consumers had no significant equity method investments. 2 Amounts include a portion of Consumers’ other common assets attributable to both the electric and gas utility businesses. 3 Amounts include purchase of capital lease additions. Amounts also include a portion of Consumers’ capital expenditures for plant and equipment attributable to both the electric and gas utility businesses.

Related Party Transactions - Co

Related Party Transactions - Consumers	12 Months Ended
	Dec. 31, 2016
Consumers Energy Company [Member]
Related Party Transactions - Consumers	19 : R elated -P arty T ransactions —C onsumers Consumers enters into a number of transactions with related parties. These transactions include: · purchases of electricity from affiliates of CMS Enterprises · payments to and from CMS Energy related to parent company overhead costs · investment in CMS Energy common stock Transactions involving power supply purchases from certain affiliates of CMS Enterprises are based on avoided costs under the Public Utility Regulatory Policies Act of 1978, state law, and competitive bidding. The payment of parent company overhead costs is based on the use of accepted industry allocation methodologies. These payments are for costs that occur in the normal course of business. Presented in the following table is Consumers ’ expense recorded from related- party transactions for the years ended December 31:    In Millions  Description Related Party 2016 2015 2014  Purchases of capacity and energy Affiliates of CMS Enterprises $ 88 $ 83 $ 89  Amounts payable to related parties for purchased power and other services were $24 million at December 31, 2016 and $23 million at December 31, 2015 . Accounts receivable from related parties were $9 million at December 31, 2016 . Accounts receivable from related parties were $17 million at December 31, 2015 , primarily representing Consumers’ payment of postretirement benefits contributions on behalf of CMS Energy. Consumers owned shares of CMS Energy common stock with a fair value of $ 33 million at December 31, 2016 and $ 29 million at December 31, 2015 . For additional details on Consumers’ investment in CMS Energy common stock, see Note 7, Financial Instruments. In October 2016, Consumers entered into two transactions with CMS ERM for the purchase of capacity for future years. The purchases, which were the result of competitive bidding, total $4 million. In January 201 7 , Consumers renewed a short-term credit agreement with CMS Energy, permitting Consumers to borrow up to $300 million. At December 31, 2016 , there were no outstanding loans under the agreement.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2016
Variable Interest Entities [Abstract]
Variable Interest Entities	20 : V ariable I nterest E ntities CMS Energy has variable interests in T .E.S. Filer City, Grayling, Genesee , and Craven . CMS Energy is not the primary beneficiary of any of these partnerships because decision making is shared among unrelated parties , and no one party has the ability to direct activities, such as operations and maintenance, plant dispatch, and fuel strategy, that most significantly impact the entities’ economic performance. The partners must agree on all major decisions for each of the partnerships. Presented in the following table is information about these partnerships:    Name (Ownership Interest) Nature of the Entity Financing of Partnership  T.E.S. Filer City ( 50% ) Coal-fueled power generator Line of credit secured by T.E.S. Filer City’s coal inventory   Grayling ( 50% ) Wood waste-fueled power generator Line of credit secured by specific assets of Grayling. This line of credit expired in 2016.   Genesee ( 50% ) Wood waste-fueled power generator Sale of revenue bonds that mature in 2021 and bear interest at fixed rates. The debt is non-recourse to the partners and secured by a CMS Energy guarantee capped at $3 million annually.   Craven ( 50% ) Wood waste-fueled power generator Line of credit secured by Craven’s property, plant, and equipment  CMS Energy has operating and management contracts with Grayling, Genesee, and Craven. Additionally, Consumers is the primary purchaser of power from T.E.S. Filer City, Grayling, and Genesee through long-term PPAs. Consumers also has reduced dispatch agreements with Grayling and Genesee, which allow these facilities to be dispatched based on the market price of power compared with the cost of production of the plants. This results in fuel cost savings that each partnership shares with Consumers’ customers. CMS Energy’s investment in these partnerships is included in investments on its consolidated balance sheets in the amount of $62 million as of December 31, 2016 and $ 61 million as of December 31, 2015 . The creditors of these partnerships do not have recourse to the general credit of CMS Energy or Consumers, except through a guarantee provided by CMS Energy of $ 3 million annually. CMS Energy has deferred collections on certain receivables owed by Genesee. CMS Energy’s maximum exposure to loss from these receivables is $8 million. Consumers has not provided any financial or other support during the periods presented that was not previously contractually required.

Quarterly Financial And Common

Quarterly Financial And Common Stock Information	12 Months Ended
	Dec. 31, 2016
Quarterly Financial and Common Stock Information	2 1 : Q uarterly Financial and Common Stock Information (Unaudited)    In Millions, Except Per Share Amounts and Stock Prices  2016  Quarters Ended March 31 June 30 Sept 30 Dec 31  CMS Energy, including Consumers  Operating revenue $ 1,801 $ 1,371 $ 1,587 $ 1,640  Operating income 336 285 386 290  Net income 164 125 186 78  Income attributable to noncontrolling interests - 1 - 1  Net income available to common stockholders 164 124 186 77  Basic earnings per average common share 1 0.59 0.45 0.67 0.28  Diluted earnings per average common share 1 0.59 0.45 0.67 0.28  Common stock prices 2  High 42.44 45.86 46.17 42.15  Low 35.61 39.38 41.31 39.49  Consumers  Operating revenue $ 1,723 $ 1,293 $ 1,498 $ 1,550  Operating income 317 264 365 288  Net income 172 132 195 117  Preferred stock dividends - 1 - 1  Net income available to common stockholder 172 131 195 116     In Millions, Except Per Share Amounts and Stock Prices  2015  Quarters Ended March 31 June 30 Sept 30 Dec 31  CMS Energy, including Consumers  Operating revenue $ 2,111 $ 1,350 $ 1,486 $ 1,509  Operating income 397 204 317 245  Net income 202 68 148 107  Income attributable to noncontrolling interests - 1 - 1  Net income available to common stockholders 202 67 148 106  Basic earnings per average common share 1 0.73 0.25 0.53 0.39  Diluted earnings per average common share 1 0.73 0.25 0.53 0.38  Common stock prices 2  High 38.20 35.57 35.82 37.17  Low 32.83 31.39 32.10 34.24  Consumers  Operating revenue $ 2,028 $ 1,281 $ 1,417 $ 1,439  Operating income 379 192 305 246  Net income 215 84 160 135  Preferred stock dividends - 1 - 1  Net income available to common stockholder 215 83 160 134  1 The sum of the quarters may not equal annual EPS due to changes in the number of shares outstanding. 2 Based on New York Stock Exchange composite transactions.
Consumers Energy Company [Member]
Quarterly Financial and Common Stock Information	2 1 : Q uarterly Financial and Common Stock Information (Unaudited)    In Millions, Except Per Share Amounts and Stock Prices  2016  Quarters Ended March 31 June 30 Sept 30 Dec 31  CMS Energy, including Consumers  Operating revenue $ 1,801 $ 1,371 $ 1,587 $ 1,640  Operating income 336 285 386 290  Net income 164 125 186 78  Income attributable to noncontrolling interests - 1 - 1  Net income available to common stockholders 164 124 186 77  Basic earnings per average common share 1 0.59 0.45 0.67 0.28  Diluted earnings per average common share 1 0.59 0.45 0.67 0.28  Common stock prices 2  High 42.44 45.86 46.17 42.15  Low 35.61 39.38 41.31 39.49  Consumers  Operating revenue $ 1,723 $ 1,293 $ 1,498 $ 1,550  Operating income 317 264 365 288  Net income 172 132 195 117  Preferred stock dividends - 1 - 1  Net income available to common stockholder 172 131 195 116     In Millions, Except Per Share Amounts and Stock Prices  2015  Quarters Ended March 31 June 30 Sept 30 Dec 31  CMS Energy, including Consumers  Operating revenue $ 2,111 $ 1,350 $ 1,486 $ 1,509  Operating income 397 204 317 245  Net income 202 68 148 107  Income attributable to noncontrolling interests - 1 - 1  Net income available to common stockholders 202 67 148 106  Basic earnings per average common share 1 0.73 0.25 0.53 0.39  Diluted earnings per average common share 1 0.73 0.25 0.53 0.38  Common stock prices 2  High 38.20 35.57 35.82 37.17  Low 32.83 31.39 32.10 34.24  Consumers  Operating revenue $ 2,028 $ 1,281 $ 1,417 $ 1,439  Operating income 379 192 305 246  Net income 215 84 160 135  Preferred stock dividends - 1 - 1  Net income available to common stockholder 215 83 160 134  1 The sum of the quarters may not equal annual EPS due to changes in the number of shares outstanding. 2 Based on New York Stock Exchange composite transactions.

Schedule I - Condensed Financia

Schedule I - Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2016
Schedule I - Condensed Financial Information of Registrant [Abstract]
Schedule I - Condensed Financial Information of Registrant	CMS Energy Corporation Schedule I – Condensed Financial Information of Registrant CMS Energy—Parent Company Condensed Statements of Income    In Millions  Years Ended December 31 2016 2015 2014   Operating Expenses  Other operating expenses $ (15) $ (9) $ (6)  Total operating expenses (15) (9) (6)   Operating Loss (15) (9) (6)   Other Income (Expense)  Equity earnings of subsidiaries 660 625 585  Interest income 1 1 1  Other expense (19) (9) (20)  Total other income 642 617 566   Interest Charges  Interest on long-term debt 150 134 150  Intercompany interest expense and other 1 3 2  Total interest charges 151 137 152   Income Before Income Taxes 476 471 408  Income Tax Benefit (75) (52) (69)   Net Income Available to Common Stockholders $ 551 $ 523 $ 477   The accompanying notes are an integral part of these statements. CMS Energy Corporation Schedule I – Condensed Financial Information of Registrant CMS Energy—Parent Company Condensed Statements of Cash Flows    In Millions  Years Ended December 31 2016 2015 2014   Cash Flows from Operating Activities  Net income $ 551 $ 523 $ 477  Adjustments to reconcile net income to net cash provided by operating activities  Equity earnings of subsidiaries (660) (625) (585)  Dividends received from subsidiaries 499 499 544  Deferred income taxes (26) (24) 30  Other non-cash operating activities and reconciling adjustments 18 - 20  Cash provided by (used in) changes in assets and liabilities  Accounts and notes receivable 85 (86) (3)  Accounts payable (9) 16 (2)  Accrued taxes (74) (115) 97  Other current and non-current assets and liabilities 38 21 31  Net cash provided by operating activities 422 209 609   Cash Flows from Investing Activities  Investment in subsidiaries (275) (150) (495)  Return of capital - - 178  Net cash used in investing activities (275) (150) (317)   Cash Flows from Financing Activities  Proceeds from issuance of long-term debt 603 349 550  Issuance of common stock 72 43 43  Retirement of long-term debt (530) (100) (547)  Debt prepayment costs (18) - (20)  Payment of dividends on common stock (345) (320) (293)  Debt issuance costs and financing fees (5) (3) (6)  Change in notes payable 76 (28) (19)  Net cash used in financing activities (147) (59) (292)   Net Increase in Cash and Cash Equivalents, Including Restricted Amounts - - -  Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period - - -   Cash and Cash Equivalents, Including Restricted Amounts, End of Period $ - $ - $ -   The accompanying notes are an integral part of these statements. CMS Energy Corporation Schedule I – Condensed Financial Information of Registrant CMS Energy—Parent Company Condensed Balance Sheets    ASSETS  In Millions  December 31 2016 2015   Current Assets  Notes and accrued interest receivable $ 2 $ 88  Accounts receivable, including intercompany and related parties 7 9  Accrued taxes 51 -  Prepayments and other current assets 1 -  Total current assets 61 97   Plant, Property, and Equipment  Plant, property, and equipment, gross - 16  Less accumulated depreciation and amortization - 16  Total plant, property, and equipment - -   Other Non-current Assets  Notes receivable 3 -  Deferred income taxes 366 340  Investments in subsidiaries 6,674 6,240  Other investments – DB SERP 26 26  Other 4 5  Total other non-current assets 7,073 6,611   Total Assets $ 7,134 $ 6,708        LIABILITIES AND EQUITY  In Millions  December 31 2016 2015   Current Liabilities  Accounts and notes payable, including intercompany and related parties $ 141 $ 74  Accrued interest, including intercompany 28 38  Accrued taxes - 23  Other current liabilities 10 5  Total current liabilities 179 140   Non-current Liabilities  Long-term debt 2,678 2,605  Postretirement benefits 21 22  Other non-current liabilities 3 3  Total non-current liabilities 2,702 2,630   Equity  Common stockholders’ equity 4,253 3,938   Total Liabilities and Equity $ 7,134 $ 6,708   The accompanying notes are an integral part of these statements. CMS Energy Corporation Schedule I – Condensed Financial Information of Registrant CMS Energy—Parent Company Notes to the Condensed Financial Statements 1: Basis of Presentation CMS Energy’s condensed financial statements have been prepared on a parent-only basis. In accordance with Rule 12 ‑04 of Regulation S ‑X, these parent-only financial statements do not include all of the information and notes required by GAAP for annual financial statements, and therefore these parent-only financial statements and other information included should be read in conjunction with CMS Energy’s audited consolidated financial statements contained within Item 8. Financial Statements and Supplementary Data. 2: Guarantees CMS Energy has issued guarantees with a maximum potential obligation of $324 million on behalf of some of its wholly owned subsidiaries and related parties. CMS Energy’s maximum potential obligation consists primarily of potential payments: · to third parties under certain commodity purchase and swap agreements entered into with CMS ERM · to third parties in support of non ‑recourse revenue bonds issued by Genesee · to the MDEQ on behalf of CMS Land and CMS Capital, for environmental remediation obligations at Bay Harbor · to the U.S. Department of Energy on behalf of Consumers, in connection with Consumers’ 2011 settlement agreement with the U.S. Department of Energy regarding damages resulting from the department’s failure to accept spent nuclear fuel from nuclear power plants formerly owned by Consumers The expiry dates of these guarantees vary, depending upon contractual provisions or upon the statute of limitations under the relevant governing law.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts and Reserves	12 Months Ended
	Dec. 31, 2016
Schedule II - Valuation and Qualifying Accounts and Reserves	CMS Energy Corporation Schedule II – Valuation and Qualifying Accounts and Reserves Years Ended December 31, 2016 , 2015 , and 2014    In Millions  Description Balance at Beginning of Period Charged to Expense Charged to Other Accounts Deductions Balance at End of Period   Allowance for uncollectible accounts 1  2016 $ 28 $ 31 $ - $ 35 $ 24  2015 40 50 - 62 28  2014 33 72 - 65 40   Deferred tax valuation allowance  2016 $ 4 $ 1 $ - $ - $ 5  2015 2 3 (1) - 4  2014 2 - - - 2   Allowance for notes receivable 1  2016 $ 9 $ 19 $ - $ 12 $ 16  2015 8 8 - 7 9  2014 5 8 - 5 8  1 Deductions are write-offs of uncollectible accounts, net of recoveries. Consumers Energy Company Schedule II – Valuation and Qualifying Accounts and Reserves Years Ended December 31, 2016 , 2015 , and 2014    In Millions  Description Balance at Beginning of Period Charged to Expense Charged to Other Accounts Deductions Balance at End of Period   Allowance for uncollectible accounts 1  2016 $ 28 $ 31 $ - $ 35 $ 24  2015 39 50 - 61 28  2014 31 72 - 64 39   Deferred tax valuation allowance  2016 $ - $ - $ - $ - $ -  2015 1 - (1) - -  2014 1 - - - 1  1 Deductions are write-offs of uncollectible accounts, net of recoveries.
Consumers Energy Company [Member]
Schedule II - Valuation and Qualifying Accounts and Reserves	CMS Energy Corporation Schedule II – Valuation and Qualifying Accounts and Reserves Years Ended December 31, 2016 , 2015 , and 2014    In Millions  Description Balance at Beginning of Period Charged to Expense Charged to Other Accounts Deductions Balance at End of Period   Allowance for uncollectible accounts 1  2016 $ 28 $ 31 $ - $ 35 $ 24  2015 40 50 - 62 28  2014 33 72 - 65 40   Deferred tax valuation allowance  2016 $ 4 $ 1 $ - $ - $ 5  2015 2 3 (1) - 4  2014 2 - - - 2   Allowance for notes receivable 1  2016 $ 9 $ 19 $ - $ 12 $ 16  2015 8 8 - 7 9  2014 5 8 - 5 8  1 Deductions are write-offs of uncollectible accounts, net of recoveries. Consumers Energy Company Schedule II – Valuation and Qualifying Accounts and Reserves Years Ended December 31, 2016 , 2015 , and 2014    In Millions  Description Balance at Beginning of Period Charged to Expense Charged to Other Accounts Deductions Balance at End of Period   Allowance for uncollectible accounts 1  2016 $ 28 $ 31 $ - $ 35 $ 24  2015 39 50 - 61 28  2014 31 72 - 64 39   Deferred tax valuation allowance  2016 $ - $ - $ - $ - $ -  2015 1 - (1) - -  2014 1 - - - 1  1 Deductions are write-offs of uncollectible accounts, net of recoveries.

Significant Accounting Polici32

Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2016
Principles of Consolidation	Principles of Consolidation: CMS Energy and Consumers prepare their consolidated financial statements in conformity with GAAP. CMS Energy’s co nsolidated financial statements comprise CMS Energy, Consumers, CMS Enterprises, and all other entities in which CMS Energy has a controlling financial interest or is the primary beneficiary. Consumers’ consolidated financial statements comprise Consumers and all other entities in which it has a controlling financial interest or is the primary beneficiary. CMS Energy uses the equity method of accounting for investments in companies and partnerships that are not consolidated, where they have significant influence over operations and financial policies but are not the primary beneficiary. CMS Energy and Consumers eliminate intercompany transactions and balances.
Use of Estimates	Use of Estimates : CMS Energy and Consumers are required to make estimates using assumptions that may affect reported amounts and disclosures. Actual results could differ from those estimates.
Revenue Recognition Policy - General	Revenue Recognition Policy: CMS Energy and Consumers recognize revenue from deliveries of electricity and natural gas, and from the transportation, processing, and storage of natural gas, when services are provided. CMS Energy and Consumers record unbilled revenue for the estimated amount of energy delivered to customers but not yet billed. CMS Energy and Consumers record sales tax net and exclude it from revenue. CMS Energy recognizes revenue on sales of marketed electricity, natural gas, and other energy products at delivery.
Revenue Recognition Policy - Alternative-Revenue Programs	Alternative-Revenue Program: The energy optimization incentive mechanism provides a financial incentive if the energy savings of Consumers’ customers exceed annual targets established by the MPSC. The maximum incentive that Consumers may earn under this mechanism is 15 percent of the amount it spends on energy optimization programs, which is limited to two percent of Consumers’ retail revenue. Consumers accounts for this program as an alternative-revenue program that meets the criteria for recognizing revenue related to the incentive as soon as energy savings exceed the annual targets established by the MPSC. The 2016 Energy Law, which will become effective in April 2017, expands existing incentives for energy efficiency programs.
Revenue Recognition Policy - Self-Implemented Rates	Self-Implemented Rates: Unless prohibited by the MPSC upon a showing of good cause, Consumers is allowed to self-implement new energy rates six months after a new rate case filing if the MPSC has not issued an order in the case. The MPSC then has another six months to issue a final order. If the MPSC does not issue a final order within that period, the filed rates are considered approved. If the MPSC issues a final order within that period, the rates that Consumers self-implemented may be subject to refund, with interest. Consumers recognizes revenue associated with self-implemented rates. If Consumers considers it probable that it will be required to refund a portion of its self-implemented rates, then Consumers records a provision for revenue subject to refund. The 2016 Energy Law, which will become effective in April 2017, eliminates utilities’ self-implementation of rates under general rate cases, but provides for more timely processing of general rate cases.
Revenue Recognition Policy - EnerBank	EnerBank: EnerBank provides four types of unsecured consumer installment loans: same-as-cash, zero interest, reduced interest, and traditional. Under EnerBank’s same-as-cash programs, authorized contractors pay EnerBank a fee to provide a borrower with the option to pay off the loan interest-free during the same-as-cash period. EnerBank recognizes the fee on a straight-line basis over the same-as-cash period, which typically ranges from three to 24 months. If a borrower does not exercise its option to pay off its loan interest-free during the same-as-cash period, EnerBank charges the borrower accrued interest at the loan’s contractual rate on the outstanding balance from the origination date. Under the zero interest and reduced interest programs, authorized contractors pay EnerBank a fee to provide a borrower with no interest or reduced rates of interest for the entire term of the loan. EnerBank recognizes the fee using the interest method over the term of the loan, which ranges from one to 12 years. Unearned income associated with the fees is recorded as a reduction to notes receivable on CMS Energy’s consolidated balance sheets. EnerBank recognizes interest income using the interest method and amortizes loan origination fees, net of certain direct origination costs, over the loan term. EnerBank ceases recognizing interest income when a loan loss is confirmed or when a loan becomes 120 days past due, at which time the loan principal is charged against the allowance for loan losses. At that time, EnerBank recognizes any interest accrued but not received for such loan losses as a reversal of interest income. The loan fees and interest income earned by EnerBank are reported as operating revenue on CMS Energy’s consolidated statements of income.
Accounts Receivable	Accounts Receivable: Accounts receivable comprise trade receivables and unbilled receivables. CMS Energy and Consumers record their accounts receivable at cost, which approximates fair value. CMS Energy and Consumers establish an allowance for uncollectible accounts based on historical losses, management’s assessment of existing economic conditions, customer trends, and other factors. CMS Energy and Consumers assess late payment fees on trade receivables based on contractual past-due terms established with customers. CMS Energy and Consumers charge off accounts deemed uncollectible to operating expense.
Contingencies	Contingencies: CMS Energy and Consumers record estimated liabilities for contingencies on their consolidated financial statements when it is probable that a liability has been incurred and when the amount of loss can be reasonably estimated. For environmental remediation projects in which the timing of estimated expenditures is considered reliably determinable, CMS Energy and Consumers record the liability at its net present value, using a discount rate equal to the interest rate on monetary assets that are essentially risk-free and have maturities comparable to that of the environmental liability. CMS Energy and Consumers expense legal fees as incurred; fees incurred but not yet billed are accrued based on estimates of work performed.
Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs	Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs: Upon the issuance of long-term debt, CMS Energy and Consumers defer issuance costs, discounts, and premiums and amortize those amounts over the terms of the associated debt. Debt issuance costs are presented as a direct deduction from the carrying amount of long-term debt on the balance sheet. Upon the refinancing of long-term debt, Consumers, as a regulated entity, defers any remaining unamortized issuance costs, discounts, and premiums associated with the refinanced debt and amortizes those amounts over the term of the newly issued debt. For the non ‑regulated portions of CMS Energy’s business, any remaining unamortized issuance costs, discounts, and premiums associated with extinguished debt are charged to earnings.
Derivative Instruments	Derivative Instruments: In order to support ongoing operations, CMS Energy and Consumers enter into contracts for the future purchase and sale of various commodities, such as electricity, natural gas, and coal. These forward contracts are generally long-term in nature and result in physical delivery of the commodity at a contracted price. Most of these contracts are not subject to derivative accounting for one or more of the following reasons: · they do not have a notional amount (that is, a number of units specified in a derivative instrument, such as MWh of electricity or bcf of natural gas) · they qualify for the normal purchases and sales exception · there is not an active market for the commodity Consumers’ coal purchase contracts are not derivatives because there is not an active market for the coal it purchases. If an active market for coal develops in the future, some of these contracts may qualify as derivatives. Since Consumers is subject to regulatory accounting, the resulting fair value gains and losses would be deferred as regulatory assets or liabilities an d would not affect net income. Consumers also 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. Consumers accounts for FTRs as derivatives. All changes in fair value associated with FTRs are deferred as regulatory assets and liabilities until the instruments are settled. CMS Energy and Consumers record derivative contracts that do not qualify for the normal purchases and sales exception at fair value on their consolidated balance sheets. Each reporting period, the resulting asset or liability is adjusted to reflect any change in the fair value of the contract. Since none of CMS Energy’s or Consumers’ derivatives has been designated as an accounting hedge, all changes in fair value are either reported in earnings or deferred as regulatory assets or liabilities. For details regarding CMS Energy’s and Consumers’ derivative instruments recorded at fair value, see Note 6, Fair Value Measurements.
Earnings Per Share	Earnings Per Share: CMS Energy calculates basic and diluted EPS using the weighted-average number of shares of common stock and dilutive potential common stock outstanding during the period. Potential common stock, for purposes of determining diluted EPS, includes the effects of nonvested stock awards and contingently convertible securities. CMS Energy computes the effect on potential common stock using the treasury stock method or the if ‑converted method, as applicable. Diluted EPS excludes the impact of antidilutive securities, which are those securities resulting in an increase in EPS or a decrease in loss per share. For EPS computations, see Note 15, Earnings Per Share—CMS Energy.
Financial Instruments	Financial Instruments: CMS Energy and Consumers record debt and equity securities classified as available for sale at fair value as determined from quoted market prices or other observable, market-based inputs. Unrealized gains and losses resulting from changes in fair value of these securities are determined on a specific-identification basis. CMS Energy and Consumers report unrealized gains and losses on these securities, net of tax, in equity as part of AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. For additional details regarding financial instruments, see Note 7, Financial Instruments.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets and Equity Method Investments: CMS Energy and Consumers perform tests of impairment if certain triggering events occur or if there has been a decline in value that may be other than temporary. CMS Energy and Consumers evaluate long-lived assets held in use for impairment by calculating the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. If the undiscounted future cash flows are less than the carrying amount, CMS Energy and Consumers recognize an impairment loss equal to the amount by which the carrying amount exceeds the fair value. CMS Energy and Consumers estimate the fair value of the asset using quoted market prices, market prices of similar assets, or discounted future cash flow analyses.
Impairment of Equity Method Investments	CMS Energy also assesses equity method investments for impairment whenever there has been a decline in value that is other than temporary. This assessment requires CMS Energy to determine the fair value of the equity method investment. CMS Energy determines fair value using valuation methodologies, including discounted cash flows, and assesses the ability of the investee to sustain an earnings capacity that justifies the carrying amount of the investment. CMS Energy records an impairment if the fair value is less than the carrying amount and the decline in value is considered to be other than temporary.
Inventory - Gas and Coal	Inventory: CMS Energy and Consumers use the weighted-average cost method for valuing working gas, recoverable base gas in underground storage facilities, and materials and supplies inventory. CMS Energy and Consumers also use this method for valuing coal inventory, and they classify these amounts as generating plant fuel stock on their consolidated balance sheets.
Inventory - RECs and Emission Allowances	CMS Energy and Consumers account for RECs and emission allowances as inventory and use the weighted-average cost method to remove amounts from inventory. RECs and emission allowances are used to satisfy compliance obligations related to the generation of power. CMS Energy and Consumers classify these amounts within other assets on their consolidated balance sheets.
Inventory - Impairment	CMS Energy and Consumers evaluate inventory for impairment as required to ensure that its carrying value does not exceed the lower of cost or net realizable value.
MISO Transactions	MISO Transactions: MISO requires the submission of hourly day-ahead and real-time bids and offers for energy at locations across the MISO region. CMS Energy and Consumers account for MISO transactions on a net hourly basis in each of the real-time and day-ahead markets, netted across all MISO energy market locations. CMS Energy and Consumers record net hourly purchases in purchased and interchange power and net hourly sales in operating revenue on their consolidated statements of income. They record net billing adjustments upon receipt of settlement statements, record accruals for future net purchases and sales adjustments based on historical experience, and reconcile accruals to actual expenses and sales upon receipt of settlement statements.
Property Taxes	Property Taxes: Property taxes are based on the taxable value of Consumers’ real and personal property assessed by local taxing authorities. Consumers records property tax expense over the fiscal year of the taxing authority for which the taxes are levied based on Consumers’ budgeted customer sales. The deferred property tax balance represents the amount of Consumers’ accrued property tax that will be recognized over future governmental fiscal periods.
Renewable Energy Grant	Renewable Energy Grant: In 2013, Consumers received a renewable energy cash grant for Lake Winds ® Energy Park under Section 1603 of the American Recovery and Reinvestment Tax Act of 2009. Upon receipt of the grant, Consumers recorded a regulatory liability, which Consumers is amortizing over the life of Lake Winds ® Energy Park. Consumers presents the amortization as a reduction to maintenance and other operating expenses on its consolidated statements of income. Consumers recorded the deferred income taxes related to the grant as a reduction of the book basis of Lake Winds ® Energy Park.
Consumers Energy Company [Member]
Principles of Consolidation	Principles of Consolidation: CMS Energy and Consumers prepare their consolidated financial statements in conformity with GAAP. CMS Energy’s co nsolidated financial statements comprise CMS Energy, Consumers, CMS Enterprises, and all other entities in which CMS Energy has a controlling financial interest or is the primary beneficiary. Consumers’ consolidated financial statements comprise Consumers and all other entities in which it has a controlling financial interest or is the primary beneficiary. CMS Energy uses the equity method of accounting for investments in companies and partnerships that are not consolidated, where they have significant influence over operations and financial policies but are not the primary beneficiary. CMS Energy and Consumers eliminate intercompany transactions and balances.
Use of Estimates	Use of Estimates : CMS Energy and Consumers are required to make estimates using assumptions that may affect reported amounts and disclosures. Actual results could differ from those estimates.
Revenue Recognition Policy - General	Revenue Recognition Policy: CMS Energy and Consumers recognize revenue from deliveries of electricity and natural gas, and from the transportation, processing, and storage of natural gas, when services are provided. CMS Energy and Consumers record unbilled revenue for the estimated amount of energy delivered to customers but not yet billed. CMS Energy and Consumers record sales tax net and exclude it from revenue. CMS Energy recognizes revenue on sales of marketed electricity, natural gas, and other energy products at delivery.
Revenue Recognition Policy - Alternative-Revenue Programs	Alternative-Revenue Program: The energy optimization incentive mechanism provides a financial incentive if the energy savings of Consumers’ customers exceed annual targets established by the MPSC. The maximum incentive that Consumers may earn under this mechanism is 15 percent of the amount it spends on energy optimization programs, which is limited to two percent of Consumers’ retail revenue. Consumers accounts for this program as an alternative-revenue program that meets the criteria for recognizing revenue related to the incentive as soon as energy savings exceed the annual targets established by the MPSC. The 2016 Energy Law, which will become effective in April 2017, expands existing incentives for energy efficiency programs.
Revenue Recognition Policy - Self-Implemented Rates	Self-Implemented Rates: Unless prohibited by the MPSC upon a showing of good cause, Consumers is allowed to self-implement new energy rates six months after a new rate case filing if the MPSC has not issued an order in the case. The MPSC then has another six months to issue a final order. If the MPSC does not issue a final order within that period, the filed rates are considered approved. If the MPSC issues a final order within that period, the rates that Consumers self-implemented may be subject to refund, with interest. Consumers recognizes revenue associated with self-implemented rates. If Consumers considers it probable that it will be required to refund a portion of its self-implemented rates, then Consumers records a provision for revenue subject to refund. The 2016 Energy Law, which will become effective in April 2017, eliminates utilities’ self-implementation of rates under general rate cases, but provides for more timely processing of general rate cases.
Accounts Receivable	Accounts Receivable: Accounts receivable comprise trade receivables and unbilled receivables. CMS Energy and Consumers record their accounts receivable at cost, which approximates fair value. CMS Energy and Consumers establish an allowance for uncollectible accounts based on historical losses, management’s assessment of existing economic conditions, customer trends, and other factors. CMS Energy and Consumers assess late payment fees on trade receivables based on contractual past-due terms established with customers. CMS Energy and Consumers charge off accounts deemed uncollectible to operating expense.
Contingencies	Contingencies: CMS Energy and Consumers record estimated liabilities for contingencies on their consolidated financial statements when it is probable that a liability has been incurred and when the amount of loss can be reasonably estimated. For environmental remediation projects in which the timing of estimated expenditures is considered reliably determinable, CMS Energy and Consumers record the liability at its net present value, using a discount rate equal to the interest rate on monetary assets that are essentially risk-free and have maturities comparable to that of the environmental liability. CMS Energy and Consumers expense legal fees as incurred; fees incurred but not yet billed are accrued based on estimates of work performed.
Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs	Debt Issuance Costs, Discounts, Premiums, and Refinancing Costs: Upon the issuance of long-term debt, CMS Energy and Consumers defer issuance costs, discounts, and premiums and amortize those amounts over the terms of the associated debt. Debt issuance costs are presented as a direct deduction from the carrying amount of long-term debt on the balance sheet. Upon the refinancing of long-term debt, Consumers, as a regulated entity, defers any remaining unamortized issuance costs, discounts, and premiums associated with the refinanced debt and amortizes those amounts over the term of the newly issued debt. For the non ‑regulated portions of CMS Energy’s business, any remaining unamortized issuance costs, discounts, and premiums associated with extinguished debt are charged to earnings.
Derivative Instruments	Derivative Instruments: In order to support ongoing operations, CMS Energy and Consumers enter into contracts for the future purchase and sale of various commodities, such as electricity, natural gas, and coal. These forward contracts are generally long-term in nature and result in physical delivery of the commodity at a contracted price. Most of these contracts are not subject to derivative accounting for one or more of the following reasons: · they do not have a notional amount (that is, a number of units specified in a derivative instrument, such as MWh of electricity or bcf of natural gas) · they qualify for the normal purchases and sales exception · there is not an active market for the commodity Consumers’ coal purchase contracts are not derivatives because there is not an active market for the coal it purchases. If an active market for coal develops in the future, some of these contracts may qualify as derivatives. Since Consumers is subject to regulatory accounting, the resulting fair value gains and losses would be deferred as regulatory assets or liabilities an d would not affect net income. Consumers also 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. Consumers accounts for FTRs as derivatives. All changes in fair value associated with FTRs are deferred as regulatory assets and liabilities until the instruments are settled. CMS Energy and Consumers record derivative contracts that do not qualify for the normal purchases and sales exception at fair value on their consolidated balance sheets. Each reporting period, the resulting asset or liability is adjusted to reflect any change in the fair value of the contract. Since none of CMS Energy’s or Consumers’ derivatives has been designated as an accounting hedge, all changes in fair value are either reported in earnings or deferred as regulatory assets or liabilities. For details regarding CMS Energy’s and Consumers’ derivative instruments recorded at fair value, see Note 6, Fair Value Measurements.
Financial Instruments	Financial Instruments: CMS Energy and Consumers record debt and equity securities classified as available for sale at fair value as determined from quoted market prices or other observable, market-based inputs. Unrealized gains and losses resulting from changes in fair value of these securities are determined on a specific-identification basis. CMS Energy and Consumers report unrealized gains and losses on these securities, net of tax, in equity as part of AOCI, except that unrealized losses determined to be other than temporary are reported in earnings. For additional details regarding financial instruments, see Note 7, Financial Instruments.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets and Equity Method Investments: CMS Energy and Consumers perform tests of impairment if certain triggering events occur or if there has been a decline in value that may be other than temporary. CMS Energy and Consumers evaluate long-lived assets held in use for impairment by calculating the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. If the undiscounted future cash flows are less than the carrying amount, CMS Energy and Consumers recognize an impairment loss equal to the amount by which the carrying amount exceeds the fair value. CMS Energy and Consumers estimate the fair value of the asset using quoted market prices, market prices of similar assets, or discounted future cash flow analyses.
Inventory - Gas and Coal	Inventory: CMS Energy and Consumers use the weighted-average cost method for valuing working gas, recoverable base gas in underground storage facilities, and materials and supplies inventory. CMS Energy and Consumers also use this method for valuing coal inventory, and they classify these amounts as generating plant fuel stock on their consolidated balance sheets.
Inventory - RECs and Emission Allowances	CMS Energy and Consumers account for RECs and emission allowances as inventory and use the weighted-average cost method to remove amounts from inventory. RECs and emission allowances are used to satisfy compliance obligations related to the generation of power. CMS Energy and Consumers classify these amounts within other assets on their consolidated balance sheets.
Inventory - Impairment	CMS Energy and Consumers evaluate inventory for impairment as required to ensure that its carrying value does not exceed the lower of cost or net realizable value.
MISO Transactions	MISO Transactions: MISO requires the submission of hourly day-ahead and real-time bids and offers for energy at locations across the MISO region. CMS Energy and Consumers account for MISO transactions on a net hourly basis in each of the real-time and day-ahead markets, netted across all MISO energy market locations. CMS Energy and Consumers record net hourly purchases in purchased and interchange power and net hourly sales in operating revenue on their consolidated statements of income. They record net billing adjustments upon receipt of settlement statements, record accruals for future net purchases and sales adjustments based on historical experience, and reconcile accruals to actual expenses and sales upon receipt of settlement statements.
Property Taxes	Property Taxes: Property taxes are based on the taxable value of Consumers’ real and personal property assessed by local taxing authorities. Consumers records property tax expense over the fiscal year of the taxing authority for which the taxes are levied based on Consumers’ budgeted customer sales. The deferred property tax balance represents the amount of Consumers’ accrued property tax that will be recognized over future governmental fiscal periods.
Renewable Energy Grant	Renewable Energy Grant: In 2013, Consumers received a renewable energy cash grant for Lake Winds ® Energy Park under Section 1603 of the American Recovery and Reinvestment Tax Act of 2009. Upon receipt of the grant, Consumers recorded a regulatory liability, which Consumers is amortizing over the life of Lake Winds ® Energy Park. Consumers presents the amortization as a reduction to maintenance and other operating expenses on its consolidated statements of income. Consumers recorded the deferred income taxes related to the grant as a reduction of the book basis of Lake Winds ® Energy Park.

Notes Receivable (Policy)

Notes Receivable (Policy)	12 Months Ended
	Dec. 31, 2016
Notes Receivable [Abstract]
Allowance For Loan Losses Policy	Unearned income associated with loan fees was $84 million at December 31, 2016 and $82 million at December 31, 2015. Unearned income associated with loan fees for notes receivable held for sale was $8 million at December 31, 2016 and $3 million at December 31, 2015 . 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.

Asset Retirement Obligations (P

Asset Retirement Obligations (Policy)	12 Months Ended
	Dec. 31, 2016
Asset Retirement Obligations Policy	CMS Energy and Consumers record the fair value of the cost to remove assets at the end of their useful lives, if there is a l egal obligation to remove them. If a reasonable estimate of fair value cannot be made in the period in which the ARO is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. CMS Energy and Consumers have not recorded liabilities for assets that have insignificant cumulative disposal costs, such as substation batteries. CMS Energy and Consumers calculate the fair value of ARO liabilities using an expected present-value technique that reflects assumptions about costs and inflation, and uses a credit-adjusted risk-free rate to discount the expected cash flows. CMS Energy’s ARO liabilities are primarily at Consumers. As a regulated entity, Consumers defers the effects of any changes in assumptions on the fair values of its ARO liabilities, adjusting the associated regulatory assets or liabilities rather than recognizing such effects in earnings.
Consumers Energy Company [Member]
Asset Retirement Obligations Policy	CMS Energy and Consumers record the fair value of the cost to remove assets at the end of their useful lives, if there is a l egal obligation to remove them. If a reasonable estimate of fair value cannot be made in the period in which the ARO is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. CMS Energy and Consumers have not recorded liabilities for assets that have insignificant cumulative disposal costs, such as substation batteries. CMS Energy and Consumers calculate the fair value of ARO liabilities using an expected present-value technique that reflects assumptions about costs and inflation, and uses a credit-adjusted risk-free rate to discount the expected cash flows. CMS Energy’s ARO liabilities are primarily at Consumers. As a regulated entity, Consumers defers the effects of any changes in assumptions on the fair values of its ARO liabilities, adjusting the associated regulatory assets or liabilities rather than recognizing such effects in earnings.

Income Taxes (Policy)

Income Taxes (Policy)	12 Months Ended
	Dec. 31, 2016
Income Tax Policy	CMS Energy and its subsidiaries file a consolidated U.S. federal income tax return and a unitary Michigan income tax return. Income taxes are allocated based on each company’s separate taxable income in accordance with the CMS Energy tax sharing agreement.
Consumers Energy Company [Member]
Income Tax Policy	CMS Energy and its subsidiaries file a consolidated U.S. federal income tax return and a unitary Michigan income tax return. Income taxes are allocated based on each company’s separate taxable income in accordance with the CMS Energy tax sharing agreement.

Cash And Cash Equivalents (Poli

Cash And Cash Equivalents (Policy)	12 Months Ended
	Dec. 31, 2016
Cash and Cash Equivalents	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: 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.
Consumers Energy Company [Member]
Cash and Cash Equivalents	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: 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.

New Accounting Standards (Table

New Accounting Standards (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule Of Restricted Cash Balances	   In Millions  Years Ended December 31 2015 2014  CMS Energy, including Consumers  Increase (decrease) in:  Cash and cash equivalents, including restricted amounts, beginning of period $ 42 $ 32  Net cash used in investing activities (20) 10  Cash and cash equivalents, including restricted amounts, end of period 22 42  Consumers  Increase (decrease) in:  Cash and cash equivalents, including restricted amounts, beginning of period $ 41 $ 31  Net cash used in investing activities (20) 10  Cash and cash equivalents, including restricted amounts, end of period 21 41 
Consumers Energy Company [Member]
Schedule Of Restricted Cash Balances	   In Millions  Years Ended December 31 2015 2014  CMS Energy, including Consumers  Increase (decrease) in:  Cash and cash equivalents, including restricted amounts, beginning of period $ 42 $ 32  Net cash used in investing activities (20) 10  Cash and cash equivalents, including restricted amounts, end of period 22 42  Consumers  Increase (decrease) in:  Cash and cash equivalents, including restricted amounts, beginning of period $ 41 $ 31  Net cash used in investing activities (20) 10  Cash and cash equivalents, including restricted amounts, end of period 21 41 

Regulatory Matters (Tables)

Regulatory Matters (Tables) - Consumers Energy Company [Member]	12 Months Ended
	Dec. 31, 2016
Public Utility, Property, Plant and Equipment [Line Items]
Schedule of Regulatory Assets and Liabilities	    In Millions  December 31 End of Recovery or Refund Period 2016 2015  Regulatory assets  Current  Energy optimization plan incentive 1 2017 $ 17 $ 16  Total current regulatory assets $ 17 $ 16  Non-current  Postretirement benefits 2 various $ 1,373 $ 1,096  Securitized costs 3 2029 323 348  ARO 4 various 166 151  MGP sites 4 various 139 146  Unamortized loss on reacquired debt 4 various 54 61  Energy optimization plan incentive 1 2018 18 18  Gas storage inventory adjustments 4 various 14 18  Other various 4 2  Total non-current regulatory assets $ 2,091 $ 1,840  Total regulatory assets $ 2,108 $ 1,856  Regulatory liabilities  Current  Income taxes, net 2017 $ 64 $ 64  Reserve for customer refunds 2017 31 18  Total current regulatory liabilities $ 95 $ 82  Non-current  Cost of removal various $ 1,809 $ 1,745  Renewable energy plan 2028 83 109  ARO various 62 73  Renewable energy grant 2043 58 60  Energy optimization plan various 11 26  Income taxes, net various 7 64  Other various 11 11  Total non-current regulatory liabilities $ 2,041 $ 2,088  Total regulatory liabilities $ 2,136 $ 2,170  1 These regulatory assets have arisen from an alternative revenue program and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return. 2 This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return. 3 The MPSC has authorized a specific return on this regulatory asset. 4 These regulatory assets represent incurred costs for which the MPSC has provided, or Consumers expects, recovery without a return on investment.
Schedule of Assets and Liabilities for PSCR and GCR Underrecoveries and Overrecoveries	   In Millions  December 31 2016 2015  Liabilities  PSCR overrecoveries $ 8 $ 8  GCR overrecoveries 13 18  Accrued rate refunds $ 21 $ 26 
2016 Electric Rate Case [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Schedule of Requested Annual Rate Increase	   In Millions  Components of the rate increase  Investment in rate base $ 161  Operating and maintenance costs 21  Gross margin 17  Cost of capital 15  Working capital 11  Total $ 225 

Contingencies And Commitments (

Contingencies And Commitments (Tables)	12 Months Ended
	Dec. 31, 2016
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 48 -  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. For additional details on this guarantee, see Note 20, Variable Interest Entities.
Purchase Obligations	   In Millions  Payments Due  Total 2017 2018 2019 2020 2021 Beyond 2021  CMS Energy, including Consumers  Total PPAs $ 9,356 $ 1,008 $ 1,031 $ 1,021 $ 1,051 $ 1,044 $ 4,201  Other 1,922 931 376 187 132 32 264  Consumers  PPAs  MCV PPA $ 3,010 $ 326 $ 331 $ 330 $ 344 $ 325 $ 1,354  Palisades PPA 1,994 354 365 376 388 398 113  Related-party PPAs 899 81 82 86 88 88 474  Other PPAs 3,453 247 253 229 231 233 2,260  Total PPAs $ 9,356 $ 1,008 $ 1,031 $ 1,021 $ 1,051 $ 1,044 $ 4,201  Other 1,651 895 347 157 102 19 131 
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 48 -  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. For additional details on this guarantee, see Note 20, Variable Interest Entities.
Purchase Obligations	   In Millions  Payments Due  Total 2017 2018 2019 2020 2021 Beyond 2021  CMS Energy, including Consumers  Total PPAs $ 9,356 $ 1,008 $ 1,031 $ 1,021 $ 1,051 $ 1,044 $ 4,201  Other 1,922 931 376 187 132 32 264  Consumers  PPAs  MCV PPA $ 3,010 $ 326 $ 331 $ 330 $ 344 $ 325 $ 1,354  Palisades PPA 1,994 354 365 376 388 398 113  Related-party PPAs 899 81 82 86 88 88 474  Other PPAs 3,453 247 253 229 231 233 2,260  Total PPAs $ 9,356 $ 1,008 $ 1,031 $ 1,021 $ 1,051 $ 1,044 $ 4,201  Other 1,651 895 347 157 102 19 131 
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Site Contingency [Line Items]
Expected Remediation Cost By Year	   In Millions  2017 2018 2019 2020 2021  Consumers  Remediation and other response activity costs $ 35 $ 14 $ 19 $ 10 $ 5 
Bay Harbor [Member]
Site Contingency [Line Items]
Expected Remediation Cost By Year	   In Millions  2017 2018 2019 2020 2021  CMS Energy  Long-term liquid disposal and operating and maintenance costs $ 5 $ 4 $ 4 $ 4 $ 4 

Financings And Capitalization (

Financings And Capitalization (Tables)	12 Months Ended
	Dec. 31, 2016
Summary Of Long-Term Debt Outstanding	   In Millions  Interest Rate (%) Maturity 2016 2015  CMS Energy, including Consumers  CMS Energy, parent only  Senior notes 6.550 2017 $ - $ 250  5.050 2018 - 250  8.750 2019 300 300  6.250 2020 300 300  5.050 2022 300 300  3.875 2024 250 250  3.600 2025 250 250  3.000 2026 300 -  2.950 2027 275 -  4.700 2043 250 250  4.875 2044 300 300  Total senior notes $ 2,525 $ 2,450  Term loan facility variable 1 2018 180 180  EnerBank  Certificates of deposit 1.505 2 2017 -2026 1,198 1,098  Consumers 5,661 5,409  Total principal amount outstanding $ 9,564 $ 9,137  Current amounts (864) (684)  Net unamortized discounts (15) (12)  Unamortized issuance costs (45) (41)  Total long-term debt $ 8,640 $ 8,400  1 Outstanding borrowings bear interest at an annual interest rate of LIBOR plus 0.85 percent ( 1.61 percent at December 31, 2016 ). 2 The weighted-average interest rate for EnerBank’s certificates of deposit was 1.51 percent at December 31, 2016 and 1.36 percent at December 31, 2015 . EnerBank’s primary deposit product consists of brokered certificates of deposit with varying maturities and having a face value of $ 1,000 .
Major Long-Term Debt Transactions	   Principal Issue/Retirement  (In Millions) Interest Rate Date Maturity Date  Debt issuances  CMS Energy, parent only  Senior notes $ 300 3.000 % May 2016 May 2026  Senior notes 275 2.950 November 2016 February 2027  Total CMS Energy, parent only $ 575  Consumers  First mortgage bonds $ 450 3.250 % August 2016 August 2046  Total Consumers $ 450  Total CMS Energy $ 1,025  Debt retirements  CMS Energy, parent only  Senior notes $ 250 6.550 % December 2016 July 2017  Senior notes 250 5.050 December 2016 February 2018  Total CMS Energy, parent only $ 500  Consumers  First mortgage bonds $ 173 5.500 % August 2016 August 2016  Total Consumers $ 173  Total CMS Energy $ 673 
Debt Maturities	   In Millions  2017 2018 2019 2020 2021  CMS Energy, including Consumers  Long-term debt $ 864 $ 975 $ 1,326 $ 850 $ 103  Consumers  Long-term debt $ 375 $ 523 $ 876 $ 426 $ 27 
Revolving Credit Facilities	   In Millions  Amount of Amount Letters of Credit Amount  Expiration Date Facility Borrowed Outstanding Available  CMS Energy, parent only  May 27, 2021 1,3 $ 550 $ - $ 1 $ 549  Consumers  May 27, 2021 1,4 $ 650 $ - $ 7 $ 643  November 23, 2018 2,4 250 - - 250  May 9, 2018 4 30 - 30 -  1 In May 2016, the expiration date of this revolving credit agreement was extended from 2020 to 2021. 2 In November 2016, the expiration date of this revolving credit agreement was extended from 2017 to 2018. 3 During the year ended December 31, 2016, CMS Energy’s average borrowings totaled $ 3 million with a weighted-average interest rate of 1.68 percent. Obligations under this facility are secured by Consumers common stock. 4 Obligations under this facility are secured by first mortgage bonds of Consumers. 
Issuance Of Common Stock	   Number of Average Proceeds  Shares Issued Price per Share (In Millions)  2015 888,610 $ 33.76 $ 30  2016 1,449,171 41.40 60  Total 2,337,781 $ 38.50 $ 90 
Consumers Energy Company [Member]
Summary Of Long-Term Debt Outstanding	   In Millions  Interest Rate (%) Maturity 2016 2015  Consumers  First mortgage bonds 1 5.500 2016 $ - $ 173  5.150 2017 250 250  3.210 2017 100 100  5.650 2018 250 250  6.125 2019 350 350  6.700 2019 500 500  5.650 2020 300 300  3.770 2020 100 100  5.300 2022 250 250  2.850 2022 375 375  3.375 2023 325 325  3.190 2024 52 52  3.125 2024 250 250  3.390 2027 35 35  5.800 2035 175 175  6.170 2040 50 50  4.970 2040 50 50  4.310 2042 263 263  3.950 2043 425 425  4.100 2045 250 250  3.250 2046 450 -  4.350 2064 250 250  Total first mortgage bonds $ 5,050 $ 4,773  Securitization bonds 2.790 2 2020-2029 3 328 353  Senior notes 6.875 2018 180 180  Tax-exempt pollution control revenue bonds various 2018-2035 103 103  Total principal amount outstanding $ 5,661 $ 5,409  Current amounts (375) (198)  Net unamortized discounts (8) (5)  Unamortized issuance costs (25) (23)  Total long-term debt $ 5,253 $ 5,183  1 The weighted-average interest rate for Consumers’ first mortgage bonds was 4.57 percent at December 31, 2016 and 4.73 percent at December 31, 2015 . 2 The weighted-average interest rate for Consumers’ securitization bonds issued through its subsidiary Consumers 2014 Securitization Funding was 2.79 percent at December 31, 2016 and 2.69 percent at December 31, 2015 . 3 Principal and interest payments are made semiannually.
Major Long-Term Debt Transactions	   Principal Issue/Retirement  (In Millions) Interest Rate Date Maturity Date  Debt issuances  CMS Energy, parent only  Senior notes $ 300 3.000 % May 2016 May 2026  Senior notes 275 2.950 November 2016 February 2027  Total CMS Energy, parent only $ 575  Consumers  First mortgage bonds $ 450 3.250 % August 2016 August 2046  Total Consumers $ 450  Total CMS Energy $ 1,025  Debt retirements  CMS Energy, parent only  Senior notes $ 250 6.550 % December 2016 July 2017  Senior notes 250 5.050 December 2016 February 2018  Total CMS Energy, parent only $ 500  Consumers  First mortgage bonds $ 173 5.500 % August 2016 August 2016  Total Consumers $ 173  Total CMS Energy $ 673 
Debt Maturities	   In Millions  2017 2018 2019 2020 2021  CMS Energy, including Consumers  Long-term debt $ 864 $ 975 $ 1,326 $ 850 $ 103  Consumers  Long-term debt $ 375 $ 523 $ 876 $ 426 $ 27 
Revolving Credit Facilities	   In Millions  Amount of Amount Letters of Credit Amount  Expiration Date Facility Borrowed Outstanding Available  CMS Energy, parent only  May 27, 2021 1,3 $ 550 $ - $ 1 $ 549  Consumers  May 27, 2021 1,4 $ 650 $ - $ 7 $ 643  November 23, 2018 2,4 250 - - 250  May 9, 2018 4 30 - 30 -  1 In May 2016, the expiration date of this revolving credit agreement was extended from 2020 to 2021. 2 In November 2016, the expiration date of this revolving credit agreement was extended from 2017 to 2018. 3 During the year ended December 31, 2016, CMS Energy’s average borrowings totaled $ 3 million with a weighted-average interest rate of 1.68 percent. Obligations under this facility are secured by Consumers common stock. 4 Obligations under this facility are secured by first mortgage bonds of Consumers. 
Preferred Stock	   Optional Number of Balance  Redemption Shares Outstanding  Series Price Outstanding (In Millions)  December 31 2016 2015  Cumulative, $100 par value, authorized 7,500,000 shares, with no mandatory redemption $ 4.50 $ 110.00 373,148 $ 37 $ 37 

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Assets And Liabilities Measured At Fair Value On A Recurring Basis	   In Millions  CMS Energy, including Consumers Consumers  December 31 2016 2015 2016 2015  Assets 1  Cash equivalents $ 44 $ 158 $ - $ -  Restricted cash equivalents 19 19 19 19  CMS Energy common stock - - 33 29  Nonqualified deferred compensation plan assets 12 10 8 7  DB SERP  Cash equivalents 3 2 2 2  Mutual funds 141 146 102 104  Derivative instruments  Commodity contracts 1 1 1 1  Total $ 220 $ 336 $ 165 $ 162  Liabilities 1  Nonqualified deferred compensation plan liabilities $ 12 $ 10 $ 8 $ 7  Total $ 12 $ 10 $ 8 $ 7  1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3.
Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Level 3 Inputs	 In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Balance at beginning of period $ 1 $ 1 $ 4  Total gains (losses) included in earnings 1 1 (1) -  Total gains (losses) offset through regulatory accounting (2) 2 (15)  Purchases 2 1 (1)  Settlements (1) (2) 13  Balance at end of period $ 1 $ 1 $ 1  Consumers  Balance at beginning of period $ 1 $ 1 $ 4  Total gains included in earnings 1 1 - -  Total gains (losses) offset through regulatory accounting (2) 2 (15)  Purchases 2 - (1)  Settlements (1) (2) 13  Balance at end of period $ 1 $ 1 $ 1  1 CMS Energy and Consumers record realized gains and losses for Level 3 recurring fair value measurements in earnings as a component of maintenance and other operating expenses or purchased and interchange power on their consolidated statements of income.
Consumers Energy Company [Member]
Assets And Liabilities Measured At Fair Value On A Recurring Basis	   In Millions  CMS Energy, including Consumers Consumers  December 31 2016 2015 2016 2015  Assets 1  Cash equivalents $ 44 $ 158 $ - $ -  Restricted cash equivalents 19 19 19 19  CMS Energy common stock - - 33 29  Nonqualified deferred compensation plan assets 12 10 8 7  DB SERP  Cash equivalents 3 2 2 2  Mutual funds 141 146 102 104  Derivative instruments  Commodity contracts 1 1 1 1  Total $ 220 $ 336 $ 165 $ 162  Liabilities 1  Nonqualified deferred compensation plan liabilities $ 12 $ 10 $ 8 $ 7  Total $ 12 $ 10 $ 8 $ 7  1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3.
Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Level 3 Inputs	 In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Balance at beginning of period $ 1 $ 1 $ 4  Total gains (losses) included in earnings 1 1 (1) -  Total gains (losses) offset through regulatory accounting (2) 2 (15)  Purchases 2 1 (1)  Settlements (1) (2) 13  Balance at end of period $ 1 $ 1 $ 1  Consumers  Balance at beginning of period $ 1 $ 1 $ 4  Total gains included in earnings 1 1 - -  Total gains (losses) offset through regulatory accounting (2) 2 (15)  Purchases 2 - (1)  Settlements (1) (2) 13  Balance at end of period $ 1 $ 1 $ 1  1 CMS Energy and Consumers record realized gains and losses for Level 3 recurring fair value measurements in earnings as a component of maintenance and other operating expenses or purchased and interchange power on their consolidated statements of income.

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule Of Carrying Amounts And Fair Values Of Financial Instruments	   In Millions  December 31, 2016 December 31, 2015  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 $ - $ - $ - $ - $ -  Notes receivable 2 1,326 1,415 - - 1,415 1,161 1,228 - - 1,228  Securities held to maturity 13 13 - 13 - 11 11 - 11 -  Liabilities  Long-term debt 3 9,504 9,953 - 8,990 963 9,084 9,599 - 8,648 951  Long-term payables 4 17 17 - - 17 14 14 - - 14  Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ - $ - $ - $ - $ -  Notes receivable 5 45 45 - - 45 - - - - -  Liabilities  Long-term debt 6 5,628 5,903 - 4,940 963 5,381 5,684 - 4,733 951  1 Includes current accounts receivable of $12 million at December 31, 2016 . 2 Includes current portion of notes receivable of $ 219 million at December 31, 2016 and $ 144 million at December 31, 2015 . 3 Includes current portion of long-term debt of $ 864 million at December 31, 2016 and $ 684 million at December 31, 2015 . 4 Includes current portion of long-term payables of $ 1 million at December 31, 2016 and 2015 . 5 Includes current portion of notes receivable of $29 million at Decemb er 31, 2 016 . 6 Includes current portion of long-term debt of $ 375 million at December 31, 2016 and $ 198 million at December 31, 2015 .
Schedule Of Investment Securities	   In Millions  December 31, 2016 December 31, 2015  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 $ 141 $ - $ - $ 141 $ 152 $ - $ 6 $ 146  Held to maturity  Debt securities 13 - - 13 11 - - 11  Consumers  Available for sale  DB SERP  Mutual funds $ 102 $ - $ - $ 102 $ 108 $ - $ 4 $ 104  CMS Energy common stock 4 29 - 33 4 25 - 29 
Schedule Of Sales Activity For Investment Securities	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Proceeds from sales of investment securities $ 6 $ 3 $ 8  Consumers  Proceeds from sales of investment securities $ 4 $ 2 $ 6 
Consumers Energy Company [Member]
Schedule Of Carrying Amounts And Fair Values Of Financial Instruments	   In Millions  December 31, 2016 December 31, 2015  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 $ - $ - $ - $ - $ -  Notes receivable 2 1,326 1,415 - - 1,415 1,161 1,228 - - 1,228  Securities held to maturity 13 13 - 13 - 11 11 - 11 -  Liabilities  Long-term debt 3 9,504 9,953 - 8,990 963 9,084 9,599 - 8,648 951  Long-term payables 4 17 17 - - 17 14 14 - - 14  Consumers  Assets  Long-term receivables 1 $ 22 $ 22 $ - $ - $ 22 $ - $ - $ - $ - $ -  Notes receivable 5 45 45 - - 45 - - - - -  Liabilities  Long-term debt 6 5,628 5,903 - 4,940 963 5,381 5,684 - 4,733 951  1 Includes current accounts receivable of $12 million at December 31, 2016 . 2 Includes current portion of notes receivable of $ 219 million at December 31, 2016 and $ 144 million at December 31, 2015 . 3 Includes current portion of long-term debt of $ 864 million at December 31, 2016 and $ 684 million at December 31, 2015 . 4 Includes current portion of long-term payables of $ 1 million at December 31, 2016 and 2015 . 5 Includes current portion of notes receivable of $29 million at Decemb er 31, 2 016 . 6 Includes current portion of long-term debt of $ 375 million at December 31, 2016 and $ 198 million at December 31, 2015 .
Schedule Of Investment Securities	   In Millions  December 31, 2016 December 31, 2015  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 $ 141 $ - $ - $ 141 $ 152 $ - $ 6 $ 146  Held to maturity  Debt securities 13 - - 13 11 - - 11  Consumers  Available for sale  DB SERP  Mutual funds $ 102 $ - $ - $ 102 $ 108 $ - $ 4 $ 104  CMS Energy common stock 4 29 - 33 4 25 - 29 
Schedule Of Sales Activity For Investment Securities	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Proceeds from sales of investment securities $ 6 $ 3 $ 8  Consumers  Proceeds from sales of investment securities $ 4 $ 2 $ 6 

Notes Receivable (Tables)

Notes Receivable (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule Of Current And Non-Current Notes Receivable	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Current  EnerBank notes receivable, net of allowance for loan losses $ 151 $ 128  EnerBank notes receivable held for sale 39 16  State of Michigan tax settlement 29 -  Non-current  EnerBank notes receivable 1,088 1,017  State of Michigan tax settlement 19 -  Total notes receivable $ 1,326 $ 1,161  Consumers  Current  State of Michigan tax settlement $ 29 $ -  Non-current  State of Michigan tax settlement 16 -  Total notes receivable $ 45 $ - 
Schedule Of Allowance For Loan Losses	   In Millions  Years Ended December 31 2016 2015  Balance at beginning of period $ 9 $ 8  Charge-offs (14) (8)  Recoveries 2 1  Provision for loan losses 19 8  Balance at end of period $ 16 $ 9 
Consumers Energy Company [Member]
Schedule Of Current And Non-Current Notes Receivable	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Current  EnerBank notes receivable, net of allowance for loan losses $ 151 $ 128  EnerBank notes receivable held for sale 39 16  State of Michigan tax settlement 29 -  Non-current  EnerBank notes receivable 1,088 1,017  State of Michigan tax settlement 19 -  Total notes receivable $ 1,326 $ 1,161  Consumers  Current  State of Michigan tax settlement $ 29 $ -  Non-current  State of Michigan tax settlement 16 -  Total notes receivable $ 45 $ - 

Plant, Property, and Equipment

Plant, Property, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule Of Property, Plant And Equipment	   In Millions  December 31 Estimated Depreciable Life in Years 2016 2015  CMS Energy, including Consumers  Plant, property, and equipment, gross  Consumers 5 - 125 $ 20,838 $ 18,797  Enterprises  Independent power production 3 - 30 141 95  Other 3 - 40 16 25  Other 1 - 7 15 26  Plant, property, and equipment, gross $ 21,010 $ 18,943  Construction work in progress 761 1,509  Less accumulated depreciation and amortization (6,056) (5,747)  Total plant, property, and equipment 1 $ 15,715 $ 14,705  Consumers  Plant, property, and equipment, gross  Electric  Generation 22 - 125 $ 5,900 $ 4,925  Distribution 20 - 75 7,149 6,809  Transmission 46 - 75 59 -  Other 5 - 50 1,137 1,039  Assets under capital leases and financing obligation 295 286  Gas  Distribution 28 - 80 3,806 3,497  Transmission 17 - 75 1,124 981  Underground storage facilities 2 29 - 65 630 601  Other 5 - 50 708 630  Capital leases 15 14  Other non-utility property 8 - 51 15 15  Plant, property, and equipment, gross $ 20,838 $ 18,797  Construction work in progress 759 1,467  Less accumulated depreciation and amortization (5,994) (5,676)  Total plant, property, and equipment 1 $ 15,603 $ 14,588  1 For the year ended December 31, 20 16 , Consumers’ plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 20 15 , Consumers’ plant additions were $ 1.4 billion and plant retirements were $ 187 million. 2 Underground storage includes base natural gas of $26 million at December 31, 20 16 and 2015 . Base natural gas is not subject to depreciation.
Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization Table	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Utility plant assets $ 5,993 $ 5,674  Non-utility plant assets 63 73  Consumers  Utility plant assets $ 5,993 $ 5,674  Non-utility plant assets 1 2 
Schedule Of Depreciation And Amortization	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Depreciation expense – plant, property, and equipment $ 687 $ 591 $ 551  Amortization expense  Software 96 70 50  Other intangible assets 3 4 4  Securitized regulatory assets 25 83 75  Other regulatory assets - 2 5  Total depreciation and amortization expense $ 811 $ 750 $ 685  Consumers  Depreciation expense – plant, property, and equipment $ 680 $ 586 $ 546  Amortization expense  Software 95 69 49  Other intangible assets 3 4 3  Securitized regulatory assets 25 83 75  Other regulatory assets - 2 5  Total depreciation and amortization expense $ 803 $ 744 $ 678 
Schedule Of Estimated Amortization Expense For Intangibles	   In Millions  2017 2018 2019 2020 2021  CMS Energy, including Consumers  Intangible asset amortization expense $ 115 $ 120 $ 112 $ 95 $ 77  Consumers  Intangible assets amortization expense $ 114 $ 119 $ 111 $ 94 $ 77 
Schedule of Finite-Lived Intangible Assets by Major Class Table	   In Millions  December 31, 2016 December 31, 2015  Description Amortization Life in Years Gross Cost 1 Accumulated Amortization Gross Cost 1 Accumulated Amortization  CMS Energy, including Consumers  Software development 1 - 15 $ 853 $ 367 $ 734 $ 294  Rights of way 50 - 75 155 48 153 46  Franchises and consents 5 - 30 15 8 15 8  Leasehold improvements various 2 7 6 7 5  Other intangibles various 22 15 21 15  Total $ 1,052 $ 444 $ 930 $ 368  Consumers  Software development 3 - 15 $ 845 $ 363 $ 729 $ 291  Rights of way 50 - 75 155 48 153 46  Franchises and consents 5 - 30 15 8 15 8  Leasehold improvements various 2 7 6 7 5  Other intangibles various 21 15 21 15  Total $ 1,043 $ 440 $ 925 $ 365  1 For the year ended December 31, 20 16 , Consumers’ intangible asset additions were $141 million and intangible asset retirements were $23 million. For the year ended December 31, 20 15 , Consumers’ intangible asset additions were $ 140 million and there were no retirements . 2 Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended.
Consumers Energy Company [Member]
Schedule Of Property, Plant And Equipment	   In Millions  December 31 Estimated Depreciable Life in Years 2016 2015  CMS Energy, including Consumers  Plant, property, and equipment, gross  Consumers 5 - 125 $ 20,838 $ 18,797  Enterprises  Independent power production 3 - 30 141 95  Other 3 - 40 16 25  Other 1 - 7 15 26  Plant, property, and equipment, gross $ 21,010 $ 18,943  Construction work in progress 761 1,509  Less accumulated depreciation and amortization (6,056) (5,747)  Total plant, property, and equipment 1 $ 15,715 $ 14,705  Consumers  Plant, property, and equipment, gross  Electric  Generation 22 - 125 $ 5,900 $ 4,925  Distribution 20 - 75 7,149 6,809  Transmission 46 - 75 59 -  Other 5 - 50 1,137 1,039  Assets under capital leases and financing obligation 295 286  Gas  Distribution 28 - 80 3,806 3,497  Transmission 17 - 75 1,124 981  Underground storage facilities 2 29 - 65 630 601  Other 5 - 50 708 630  Capital leases 15 14  Other non-utility property 8 - 51 15 15  Plant, property, and equipment, gross $ 20,838 $ 18,797  Construction work in progress 759 1,467  Less accumulated depreciation and amortization (5,994) (5,676)  Total plant, property, and equipment 1 $ 15,603 $ 14,588  1 For the year ended December 31, 20 16 , Consumers’ plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 20 15 , Consumers’ plant additions were $ 1.4 billion and plant retirements were $ 187 million. 2 Underground storage includes base natural gas of $26 million at December 31, 20 16 and 2015 . Base natural gas is not subject to depreciation.
Schedule of Capital Leased Asssets	   In Millions  Years Ended December 31 2016 2015  Consumers  Balance at beginning of period $ 300 $ 295  Additions 13 17  Net retirements and other adjustments (3) (12)  Balance at end of period $ 310 $ 300 
Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization Table	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Utility plant assets $ 5,993 $ 5,674  Non-utility plant assets 63 73  Consumers  Utility plant assets $ 5,993 $ 5,674  Non-utility plant assets 1 2 
Public Utilities Property Plant and Equipment Schedule of Composite Depreciation Rate Table	   Years Ended December 31 2016 2015 2014  Electric utility property 3.9 % 3.5 % 3.5 %  Gas utility property 2.9 2.8 2.8  Other property 9.8 8.7 7.7 
Public Utilities, Allowance for Funds Used During Construction, Schedule of Composite Rate Table	   Years Ended December 31 2016 2015 2014  AFUDC capitalization rate 7.0 % 7.1 % 7.2 % 
Schedule Of Depreciation And Amortization	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Depreciation expense – plant, property, and equipment $ 687 $ 591 $ 551  Amortization expense  Software 96 70 50  Other intangible assets 3 4 4  Securitized regulatory assets 25 83 75  Other regulatory assets - 2 5  Total depreciation and amortization expense $ 811 $ 750 $ 685  Consumers  Depreciation expense – plant, property, and equipment $ 680 $ 586 $ 546  Amortization expense  Software 95 69 49  Other intangible assets 3 4 3  Securitized regulatory assets 25 83 75  Other regulatory assets - 2 5  Total depreciation and amortization expense $ 803 $ 744 $ 678 
Schedule Of Estimated Amortization Expense For Intangibles	   In Millions  2017 2018 2019 2020 2021  CMS Energy, including Consumers  Intangible asset amortization expense $ 115 $ 120 $ 112 $ 95 $ 77  Consumers  Intangible assets amortization expense $ 114 $ 119 $ 111 $ 94 $ 77 
Schedule of Finite-Lived Intangible Assets by Major Class Table	   In Millions  December 31, 2016 December 31, 2015  Description Amortization Life in Years Gross Cost 1 Accumulated Amortization Gross Cost 1 Accumulated Amortization  CMS Energy, including Consumers  Software development 1 - 15 $ 853 $ 367 $ 734 $ 294  Rights of way 50 - 75 155 48 153 46  Franchises and consents 5 - 30 15 8 15 8  Leasehold improvements various 2 7 6 7 5  Other intangibles various 22 15 21 15  Total $ 1,052 $ 444 $ 930 $ 368  Consumers  Software development 3 - 15 $ 845 $ 363 $ 729 $ 291  Rights of way 50 - 75 155 48 153 46  Franchises and consents 5 - 30 15 8 15 8  Leasehold improvements various 2 7 6 7 5  Other intangibles various 21 15 21 15  Total $ 1,043 $ 440 $ 925 $ 365  1 For the year ended December 31, 20 16 , Consumers’ intangible asset additions were $141 million and intangible asset retirements were $23 million. For the year ended December 31, 20 15 , Consumers’ intangible asset additions were $ 140 million and there were no retirements . 2 Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended.
Jointly Owned Regulated Utility Facilities	   In Millions, Except Ownership Share  J.H. Campbell Unit 3 Ludington Distribution  Ownership share 93.3 % 51.0 % various  Utility plant in service $ 1,648 $ 291 $ 206  Accumulated depreciation (529) (150) (63)  Construction work in progress 13 157 7  Net investment $ 1,132 $ 298 $ 150 

Leases And Palisades Financing

Leases And Palisades Financing (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule of Rent Expense	   In Millions  Years Ended December 31 2016 2015 2014  Consumers  Minimum operating lease expense  PPAs $ 6 $ 6 $ 6  Other agreements 14 19 19  Contingent rental expense 1 82 82 85  1 Contingent rental expense is related to capital and operating lease PPAs and is based on delivery of energy and capacity in excess of minimum lease payments.
Schedule of Future Minimum Lease Payments for Leases	    In Millions  Capital Leases Palisades Financing Operating Leases  Consumers  2017 $ 15 $ 17 $ 20  2018 14 16 16  2019 14 15 10  2020 12 14 10  2021 11 14 10  2022 and thereafter 25 3 15  Total minimum lease payments $ 91 $ 79 $ 81  Less imputed interest 28 10  Present value of net minimum lease payments $ 63 $ 69  Less current portion 9 13  Non-current portion $ 54 $ 56 
Consumers Energy Company [Member]
Schedule of Rent Expense	   In Millions  Years Ended December 31 2016 2015 2014  Consumers  Minimum operating lease expense  PPAs $ 6 $ 6 $ 6  Other agreements 14 19 19  Contingent rental expense 1 82 82 85  1 Contingent rental expense is related to capital and operating lease PPAs and is based on delivery of energy and capacity in excess of minimum lease payments.
Schedule of Future Minimum Lease Payments for Leases	    In Millions  Capital Leases Palisades Financing Operating Leases  Consumers  2017 $ 15 $ 17 $ 20  2018 14 16 16  2019 14 15 10  2020 12 14 10  2021 11 14 10  2022 and thereafter 25 3 15  Total minimum lease payments $ 91 $ 79 $ 81  Less imputed interest 28 10  Present value of net minimum lease payments $ 63 $ 69  Less current portion 9 13  Non-current portion $ 54 $ 56 

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule of Change in Asset Retirement Obligation	   In Millions  ARO ARO  Liability Cash flow Liability  Company and ARO Description 12/31/2015 Incurred Settled Accretion Revisions 12/31/2016  CMS Energy, including Consumers  Consumers $ 438 $ 3 $ (18) $ 23 $ - $ 446  Gas treating plant and gas wells 1 - - - - 1  Total CMS Energy $ 439 $ 3 $ (18) $ 23 $ - $ 447  Consumers  Coal ash disposal areas $ 200 $ - $ (8) $ 9 $ - $ 201  Gas distribution cut, purge, and cap 178 2 (9) 11 - 182  Asbestos abatement 54 - (1) 3 - 56  Renewable generation assets 6 1 - - - 7  Total Consumers $ 438 $ 3 $ (18) $ 23 $ - $ 446     In Millions  ARO ARO  Liability Cash flow Liability  Company and ARO Description 12/31/2014 Incurred Settled Accretion Revisions 12/31/2015  CMS Energy, including Consumers  Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438  Gas treating plant and gas wells 1 - - - - 1  Total CMS Energy $ 340 $ 11 $ (6) $ 20 $ 74 $ 439  Consumers  Coal ash disposal areas $ 120 $ - $ - $ 6 $ 74 $ 200  Gas distribution cut, purge, and cap 162 11 (6) 11 - 178  Asbestos abatement 51 - - 3 - 54  Renewable generation assets 6 - - - - 6  Total Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438 
Consumers Energy Company [Member]
Schedule of Change in Asset Retirement Obligation	   In Millions  ARO ARO  Liability Cash flow Liability  Company and ARO Description 12/31/2015 Incurred Settled Accretion Revisions 12/31/2016  CMS Energy, including Consumers  Consumers $ 438 $ 3 $ (18) $ 23 $ - $ 446  Gas treating plant and gas wells 1 - - - - 1  Total CMS Energy $ 439 $ 3 $ (18) $ 23 $ - $ 447  Consumers  Coal ash disposal areas $ 200 $ - $ (8) $ 9 $ - $ 201  Gas distribution cut, purge, and cap 178 2 (9) 11 - 182  Asbestos abatement 54 - (1) 3 - 56  Renewable generation assets 6 1 - - - 7  Total Consumers $ 438 $ 3 $ (18) $ 23 $ - $ 446     In Millions  ARO ARO  Liability Cash flow Liability  Company and ARO Description 12/31/2014 Incurred Settled Accretion Revisions 12/31/2015  CMS Energy, including Consumers  Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438  Gas treating plant and gas wells 1 - - - - 1  Total CMS Energy $ 340 $ 11 $ (6) $ 20 $ 74 $ 439  Consumers  Coal ash disposal areas $ 120 $ - $ - $ 6 $ 74 $ 200  Gas distribution cut, purge, and cap 162 11 (6) 11 - 178  Asbestos abatement 51 - - 3 - 54  Renewable generation assets 6 - - - - 6  Total Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438 

Retirement Benefits (Tables)

Retirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Schedule Of SERP Trust Assets, ABO And Contributions	   In Millions  Years Ended December 31 2016 2015  CMS Energy, including Consumers  Trust assets $ 144 $ 148  ABO 143 140  Contributions - 25  Consumers  Trust assets $ 104 $ 106  ABO 101 97  Contributions - 17 
Schedule Of Effect Of One-Percentage-Point Change In Assumed Health Care Cost Trend Rates	   In Millions  One Percentage One Percentage  Year Ended December 31, 2016 Point Increase Point Decrease  CMS Energy, including Consumers  Effect on total service and interest cost component $ 13 $ (10)  Effect on PBO 201 (163)  Consumers  Effect on total service and interest cost component $ 13 $ (10)  Effect on PBO 196 (159) 
Schedule Of Assumptions Used	   December 31 2016 2015 2014  CMS Energy, including Consumers  Weighted average for benefit obligations 1  Discount rate 2,3  DB Pension Plan 4.30 % 4.52 % 4.10 %  DB SERP 4.16 4.43 4.10  OPEB Plan 4.49 4.70 4.30  Rate of compensation increase  DB Pension Plan 3.60 3.00 3.00  DB SERP 5.50 5.50 5.50  Weighted average for net periodic benefit cost 1  Service cost discount rate 2,3  DB Pension Plan 4.79 4.10 4.90  DB SERP 4.87 4.10 4.90  OPEB Plan 4.75 4.30 5.10  Interest cost discount rate 2,3  DB Pension Plan 3.66 4.10 4.90  DB SERP 3.64 4.10 4.90  OPEB Plan 3.89 4.30 5.10  Expected long-term rate of return on plan assets 4  DB Pension Plan 7.25 7.50 7.50  OPEB Plan 7.25 7.25 7.25  Rate of compensation increase  DB Pension Plan 3.00 3.00 3.00  DB SERP 5.50 5.50 5.50  1 The mortality assumption for benefit obligations was based on the RP- 2014 mortality table, with projection scales MP-2016 for 2016, MP-2015 for 2015, and MP-2014 for 2014 . The mortality assumption for net periodic benefit cost for 2016 and 2015 was based on the RP - 2014 mortality table , with projection scales MP-2015 for 2016 and MP-2014 for 2015, and for 201 4 was based on the RP - 2000 mortality table. 2 The discount rate reflects the rate at which benefits could be effectively settled and is equal to the equivalent single rate resulting from a yield - curve analysis. This analysis incorporated the projected benefit payments specific to CMS Energy’s and Consumers’ DB Pension Plan and OPEB Plan and the yields on high - quality corporate bonds rated Aa or better. 3 In January 2016, CMS Energy and Consumers changed the method they use to determine the discount rate used to calculate the service cost and interest cost components of net periodic benefit costs for the DB Pension and OPEB Plans. Historically, the discount rate used for this purpose represented a single weighted - average rate derived from the yield curve used to determine the benefit obligation. CMS Energy and Consumers have elected to use instead a full - yield - curve approach in the estimation of service cost and interest cost ; this approach is more accurate in that it applies individual spot rates along the yield curve to future projected benefit payments based on the time of payment. This change represented a change in accounting estimate and did not impact years prior to 2016. As a result of changing to the full-yield-curve approach to determine the discount rate, for the year ended December 31, 2016, the service cost and interest cost components of net periodic benefit costs were reduced by $23 million for the DB Pension Plan and $12 million for the OPEB Plan for CMS Energy and by $22 million for the DB Pension Plan and $11 million for the OPEB Plan for Consumers. 4 CMS Energy and Consumers determined the long-term rate of return using historical market returns, the present and expected future economic environment, the capital market principles of risk and return, and the expert opinions of individuals and firms with financial market knowledge. CMS Energy and Consumers considered the asset allocation of the portfolio in forecasting the future expected total return of the portfolio. The goal was to determine a long-term rate of return that could be incorporated into the planning of future cash flow requirements in conjunction with the change in the liability. Annually, CMS Energy and Consumers review for reasonableness and appropriateness the forecasted returns for various classes of assets used to construct an expected return model. CMS Energy’s and Consumers’ expected long-term rate of return on DB Pension Plan assets was 7. 2 5 percent in 2016 . The actual return (loss) on DB Pension Plan assets was 8.0 percent in 2016 , (2.0) percent in 2015 , and 7.4 percent in 2014 .
Schedule Of Net Benefit Costs	    In Millions  DB Pension Plan and DB SERP OPEB Plan  Years Ended December 31 2016 2015 2014 2016 2015 2014  CMS Energy, including Consumers  Net periodic cost (credit)  Service cost $ 42 $ 50 $ 42 $ 18 $ 25 $ 20  Interest cost 90 108 105 46 58 56  Expected return on plan assets (147) (138) (135) (85) (91) (88)  Amortization of:  Net loss 71 97 60 21 21 2  Prior service cost (credit) 4 1 1 (41) (41) (41)  Net periodic cost (credit) $ 60 $ 118 $ 73 $ (41) $ (28) $ (51)  Consumers  Net periodic cost (credit)  Service cost $ 41 $ 49 $ 41 $ 17 $ 25 $ 20  Interest cost 87 103 100 45 56 54  Expected return on plan assets (143) (134) (131) (80) (86) (83)  Amortization of:  Net loss 68 93 59 22 22 3  Prior service cost (credit) 4 1 1 (40) (40) (40)  Net periodic cost (credit) $ 57 $ 112 $ 70 $ (36) $ (23) $ (46) 
Schedule Of Net Loss And Prior Service Cost (Credit) That Will Be Amortized In Next Fiscal Year	   In Millions  DB Pension Plan OPEB Plan  CMS Energy, including Consumers  Regulatory asset $ 82 $ (2)  AOCI 2 (2)  Consumers  Regulatory asset $ 82 $ (2) 
Schedule Of Benefit Obligations In Excess Of Fair Value Of Plan Assets	   In Millions  DB Pension Plan DB SERP OPEB Plan  Years Ended December 31 2016 2015 2016 2015 2016 2015  CMS Energy, including Consumers  Benefit obligation at beginning of period $ 2,403 $ 2,547 $ 150 $ 156 $ 1,227 $ 1,378  Service cost 42 49 - 1 18 25  Interest cost 85 102 5 6 46 58  Plan amendments - 13 - - - (25)  Actuarial (gain) loss 196 1 (153) 1 4 (5) 171 1 (152) 1  Benefits paid (164) (155) (8) (8) (54) (57)  Benefit obligation at end of period $ 2,562 $ 2,403 $ 151 $ 150 $ 1,408 $ 1,227  Plan assets at fair value at beginning of period $ 2,013 $ 1,979 $ - $ - $ 1,208 $ 1,265  Actual return on plan assets 152 (36) - - 109 (29)  Company contribution 100 225 8 8 - 29  Actual benefits paid (164) (155) (8) (8) (53) (57)  Plan assets at fair value at end of period $ 2,101 $ 2,013 $ - $ - $ 1,264 $ 1,208  Funded status $ (461) 2 $ (390) 2 $ (151) $ (150) $ (144) $ (19)  Consumers  Benefit obligation at beginning of period $ 106 $ 111 $ 1,188 $ 1,336  Service cost - 1 17 25  Interest cost 4 4 45 56  Plan amendments - - - (24)  Actuarial (gain) loss 4 (5) 167 1 (150) 1  Benefits paid (5) (5) (52) (55)  Benefit obligation at end of period $ 109 $ 106 $ 1,365 $ 1,188  Plan assets at fair value at beginning of period $ - $ - $ 1,133 $ 1,186  Actual return on plan assets - - 103 (27)  Company contribution 5 5 - 29  Actual benefits paid (5) (5) (52) (55)  Plan assets at fair value at end of period $ - $ - $ 1,184 $ 1,133  Funded status $ (109) $ (106) $ (181) $ (55)  1 The actuarial loss for 2016 was primarily the result of claims, experience, and lowering the discount rates used in calculating the plans’ obligations. The actuarial gain for 2015 was primarily the result of increasing the discount rates used in calculating the plans’ obligations. 2 At December 31, 2016 , $ 441 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses. At December 31, 2015 , $ 368 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses.
Schedule Of Retirement Benefit Plan Assets (Liabilities)	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Current liabilities  DB SERP $ 8 $ 8  Non-current liabilities  DB Pension Plan 461 390  DB SERP 143 142  OPEB Plan 144 19  Consumers  Current liabilities  DB SERP $ 5 $ 5  Non-current liabilities  DB Pension Plan 441 368  DB SERP 104 101  OPEB Plan 181 55 
Schedule Of Accumulated And Projected Benefit Obligations	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  DB Pension Plan PBO $ 2,562 $ 2,403  DB Pension Plan ABO 2,250 2,140  Fair value of DB Pension Plan assets 2,101 2,013 
Schedule Of Net Periodic Benefit Cost Not Yet Recognized	   In Millions  DB Pension Plan and DB SERP OPEB Plan  Years Ended December 31 2016 2015 2016 2015  CMS Energy, including Consumers  Regulatory assets  Net loss $ 1,062 $ 944 $ 483 $ 360  Prior service cost (credit) 15 19 (187) (227)  Regulatory assets $ 1,077 $ 963 $ 296 $ 133  AOCI  Net loss (gain) 93 86 (8) (11)  Prior service cost (credit) 1 1 (6) (8)  Total amounts recognized in regulatory assets and AOCI $ 1,171 $ 1,050 $ 282 $ 114  Consumers  Regulatory assets  Net loss $ 1,062 $ 944 $ 483 $ 360  Prior service cost (credit) 15 19 (187) (227)  Regulatory assets $ 1,077 $ 963 $ 296 $ 133  AOCI  Net loss 33 29 - -  Total amounts recognized in regulatory assets and AOCI $ 1,110 $ 992 $ 296 $ 133 
Schedule Of Allocation Of Plan Assets	   In Millions  DB Pension Plan  December 31, 2016 December 31, 2015  Total Level 1 Level 2 Total Level 1 Level 2  CMS Energy, including Consumers  Cash and short-term investments $ 110 $ 110 $ - $ 215 $ 215 $ -  U.S. government and agencies securities 1 - 1 19 - 19  Corporate debt 266 - 266 243 - 243  State and municipal bonds 9 - 9 8 - 8  Foreign corporate bonds 25 - 25 16 - 16  Mutual funds 571 571 - 538 538 -  $ 982 $ 681 $ 301 $ 1,039 $ 753 $ 286  Pooled funds 1,119 974  Total $ 2,101 $ 2,013     In Millions  OPEB Plan  December 31, 2016 December 31, 2015  Total Level 1 Level 2 Total Level 1 Level 2  CMS Energy, including Consumers  Cash and short-term investments $ 39 $ 39 $ - $ 51 $ 51 $ -  U.S. government and agencies securities - - - 3 - 3  Corporate debt 38 - 38 34 - 34  State and municipal bonds 1 - 1 1 - 1  Foreign corporate bonds 4 - 4 2 - 2  Common stocks 44 44 - 54 54 -  Mutual funds 563 563 - 456 456 -  $ 689 $ 646 $ 43 $ 601 $ 561 $ 40  Pooled funds 575 607  Total $ 1,264 $ 1,208 
Schedule Of Pooled Funds Components	   DB Pension Plan OPEB Plan  December 31 2016 2015 2016 2015  U.S. equity securities 67 % 62 % 72 % 58 %  Foreign equity securities 16 18 13 13  U.S. fixed-income securities 9 11 8 22  Foreign fixed-income securities 4 6 4 5  Alternative investments 4 3 3 2  100 % 100 % 100 % 100 % 
Schedule Of Plan Contributions	   In Millions  Years Ended December 31 2016 2015  CMS Energy, including Consumers  OPEB Plan $ - $ 29  DB Pension Plan 100 225  Consumers  OPEB Plan $ - $ 29  DB Pension Plan 93 209 
Schedule Of Expected Benefit Payments	   In Millions  DB Pension Plan DB SERP OPEB Plan  CMS Energy, including Consumers  2017 $ 153 $ 8 $ 59  2018 159 8 63  2019 163 9 66  2020 165 11 69  2021 166 10 72  2022-2026 827 50 385  Consumers  2017 $ 149 $ 5 $ 57  2018 155 5 61  2019 159 6 64  2020 161 7 67  2021 161 7 70  2022-2026 803 32 371 
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule Of SERP Trust Assets, ABO And Contributions	   In Millions  Years Ended December 31 2016 2015  CMS Energy, including Consumers  Trust assets $ 144 $ 148  ABO 143 140  Contributions - 25  Consumers  Trust assets $ 104 $ 106  ABO 101 97  Contributions - 17 
Schedule Of Effect Of One-Percentage-Point Change In Assumed Health Care Cost Trend Rates	   In Millions  One Percentage One Percentage  Year Ended December 31, 2016 Point Increase Point Decrease  CMS Energy, including Consumers  Effect on total service and interest cost component $ 13 $ (10)  Effect on PBO 201 (163)  Consumers  Effect on total service and interest cost component $ 13 $ (10)  Effect on PBO 196 (159) 
Schedule Of Assumptions Used	   December 31 2016 2015 2014  CMS Energy, including Consumers  Weighted average for benefit obligations 1  Discount rate 2,3  DB Pension Plan 4.30 % 4.52 % 4.10 %  DB SERP 4.16 4.43 4.10  OPEB Plan 4.49 4.70 4.30  Rate of compensation increase  DB Pension Plan 3.60 3.00 3.00  DB SERP 5.50 5.50 5.50  Weighted average for net periodic benefit cost 1  Service cost discount rate 2,3  DB Pension Plan 4.79 4.10 4.90  DB SERP 4.87 4.10 4.90  OPEB Plan 4.75 4.30 5.10  Interest cost discount rate 2,3  DB Pension Plan 3.66 4.10 4.90  DB SERP 3.64 4.10 4.90  OPEB Plan 3.89 4.30 5.10  Expected long-term rate of return on plan assets 4  DB Pension Plan 7.25 7.50 7.50  OPEB Plan 7.25 7.25 7.25  Rate of compensation increase  DB Pension Plan 3.00 3.00 3.00  DB SERP 5.50 5.50 5.50  1 The mortality assumption for benefit obligations was based on the RP- 2014 mortality table, with projection scales MP-2016 for 2016, MP-2015 for 2015, and MP-2014 for 2014 . The mortality assumption for net periodic benefit cost for 2016 and 2015 was based on the RP - 2014 mortality table , with projection scales MP-2015 for 2016 and MP-2014 for 2015, and for 201 4 was based on the RP - 2000 mortality table. 2 The discount rate reflects the rate at which benefits could be effectively settled and is equal to the equivalent single rate resulting from a yield - curve analysis. This analysis incorporated the projected benefit payments specific to CMS Energy’s and Consumers’ DB Pension Plan and OPEB Plan and the yields on high - quality corporate bonds rated Aa or better. 3 In January 2016, CMS Energy and Consumers changed the method they use to determine the discount rate used to calculate the service cost and interest cost components of net periodic benefit costs for the DB Pension and OPEB Plans. Historically, the discount rate used for this purpose represented a single weighted - average rate derived from the yield curve used to determine the benefit obligation. CMS Energy and Consumers have elected to use instead a full - yield - curve approach in the estimation of service cost and interest cost ; this approach is more accurate in that it applies individual spot rates along the yield curve to future projected benefit payments based on the time of payment. This change represented a change in accounting estimate and did not impact years prior to 2016. As a result of changing to the full-yield-curve approach to determine the discount rate, for the year ended December 31, 2016, the service cost and interest cost components of net periodic benefit costs were reduced by $23 million for the DB Pension Plan and $12 million for the OPEB Plan for CMS Energy and by $22 million for the DB Pension Plan and $11 million for the OPEB Plan for Consumers. 4 CMS Energy and Consumers determined the long-term rate of return using historical market returns, the present and expected future economic environment, the capital market principles of risk and return, and the expert opinions of individuals and firms with financial market knowledge. CMS Energy and Consumers considered the asset allocation of the portfolio in forecasting the future expected total return of the portfolio. The goal was to determine a long-term rate of return that could be incorporated into the planning of future cash flow requirements in conjunction with the change in the liability. Annually, CMS Energy and Consumers review for reasonableness and appropriateness the forecasted returns for various classes of assets used to construct an expected return model. CMS Energy’s and Consumers’ expected long-term rate of return on DB Pension Plan assets was 7. 2 5 percent in 2016 . The actual return (loss) on DB Pension Plan assets was 8.0 percent in 2016 , (2.0) percent in 2015 , and 7.4 percent in 2014 .
Schedule Of Net Benefit Costs	    In Millions  DB Pension Plan and DB SERP OPEB Plan  Years Ended December 31 2016 2015 2014 2016 2015 2014  CMS Energy, including Consumers  Net periodic cost (credit)  Service cost $ 42 $ 50 $ 42 $ 18 $ 25 $ 20  Interest cost 90 108 105 46 58 56  Expected return on plan assets (147) (138) (135) (85) (91) (88)  Amortization of:  Net loss 71 97 60 21 21 2  Prior service cost (credit) 4 1 1 (41) (41) (41)  Net periodic cost (credit) $ 60 $ 118 $ 73 $ (41) $ (28) $ (51)  Consumers  Net periodic cost (credit)  Service cost $ 41 $ 49 $ 41 $ 17 $ 25 $ 20  Interest cost 87 103 100 45 56 54  Expected return on plan assets (143) (134) (131) (80) (86) (83)  Amortization of:  Net loss 68 93 59 22 22 3  Prior service cost (credit) 4 1 1 (40) (40) (40)  Net periodic cost (credit) $ 57 $ 112 $ 70 $ (36) $ (23) $ (46) 
Schedule Of Net Loss And Prior Service Cost (Credit) That Will Be Amortized In Next Fiscal Year	   In Millions  DB Pension Plan OPEB Plan  CMS Energy, including Consumers  Regulatory asset $ 82 $ (2)  AOCI 2 (2)  Consumers  Regulatory asset $ 82 $ (2) 
Schedule Of Benefit Obligations In Excess Of Fair Value Of Plan Assets	   In Millions  DB Pension Plan DB SERP OPEB Plan  Years Ended December 31 2016 2015 2016 2015 2016 2015  CMS Energy, including Consumers  Benefit obligation at beginning of period $ 2,403 $ 2,547 $ 150 $ 156 $ 1,227 $ 1,378  Service cost 42 49 - 1 18 25  Interest cost 85 102 5 6 46 58  Plan amendments - 13 - - - (25)  Actuarial (gain) loss 196 1 (153) 1 4 (5) 171 1 (152) 1  Benefits paid (164) (155) (8) (8) (54) (57)  Benefit obligation at end of period $ 2,562 $ 2,403 $ 151 $ 150 $ 1,408 $ 1,227  Plan assets at fair value at beginning of period $ 2,013 $ 1,979 $ - $ - $ 1,208 $ 1,265  Actual return on plan assets 152 (36) - - 109 (29)  Company contribution 100 225 8 8 - 29  Actual benefits paid (164) (155) (8) (8) (53) (57)  Plan assets at fair value at end of period $ 2,101 $ 2,013 $ - $ - $ 1,264 $ 1,208  Funded status $ (461) 2 $ (390) 2 $ (151) $ (150) $ (144) $ (19)  Consumers  Benefit obligation at beginning of period $ 106 $ 111 $ 1,188 $ 1,336  Service cost - 1 17 25  Interest cost 4 4 45 56  Plan amendments - - - (24)  Actuarial (gain) loss 4 (5) 167 1 (150) 1  Benefits paid (5) (5) (52) (55)  Benefit obligation at end of period $ 109 $ 106 $ 1,365 $ 1,188  Plan assets at fair value at beginning of period $ - $ - $ 1,133 $ 1,186  Actual return on plan assets - - 103 (27)  Company contribution 5 5 - 29  Actual benefits paid (5) (5) (52) (55)  Plan assets at fair value at end of period $ - $ - $ 1,184 $ 1,133  Funded status $ (109) $ (106) $ (181) $ (55)  1 The actuarial loss for 2016 was primarily the result of claims, experience, and lowering the discount rates used in calculating the plans’ obligations. The actuarial gain for 2015 was primarily the result of increasing the discount rates used in calculating the plans’ obligations. 2 At December 31, 2016 , $ 441 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses. At December 31, 2015 , $ 368 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses.
Schedule Of Retirement Benefit Plan Assets (Liabilities)	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Current liabilities  DB SERP $ 8 $ 8  Non-current liabilities  DB Pension Plan 461 390  DB SERP 143 142  OPEB Plan 144 19  Consumers  Current liabilities  DB SERP $ 5 $ 5  Non-current liabilities  DB Pension Plan 441 368  DB SERP 104 101  OPEB Plan 181 55 
Schedule Of Net Periodic Benefit Cost Not Yet Recognized	   In Millions  DB Pension Plan and DB SERP OPEB Plan  Years Ended December 31 2016 2015 2016 2015  CMS Energy, including Consumers  Regulatory assets  Net loss $ 1,062 $ 944 $ 483 $ 360  Prior service cost (credit) 15 19 (187) (227)  Regulatory assets $ 1,077 $ 963 $ 296 $ 133  AOCI  Net loss (gain) 93 86 (8) (11)  Prior service cost (credit) 1 1 (6) (8)  Total amounts recognized in regulatory assets and AOCI $ 1,171 $ 1,050 $ 282 $ 114  Consumers  Regulatory assets  Net loss $ 1,062 $ 944 $ 483 $ 360  Prior service cost (credit) 15 19 (187) (227)  Regulatory assets $ 1,077 $ 963 $ 296 $ 133  AOCI  Net loss 33 29 - -  Total amounts recognized in regulatory assets and AOCI $ 1,110 $ 992 $ 296 $ 133 
Schedule Of Plan Contributions	   In Millions  Years Ended December 31 2016 2015  CMS Energy, including Consumers  OPEB Plan $ - $ 29  DB Pension Plan 100 225  Consumers  OPEB Plan $ - $ 29  DB Pension Plan 93 209 
Schedule Of Expected Benefit Payments	   In Millions  DB Pension Plan DB SERP OPEB Plan  CMS Energy, including Consumers  2017 $ 153 $ 8 $ 59  2018 159 8 63  2019 163 9 66  2020 165 11 69  2021 166 10 72  2022-2026 827 50 385  Consumers  2017 $ 149 $ 5 $ 57  2018 155 5 61  2019 159 6 64  2020 161 7 67  2021 161 7 70  2022-2026 803 32 371 

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule Of Restricted Stock Activity	   CMS Energy, including Consumers Consumers  Year Ended December 31, 2016 Number of Shares Weighted-Average Grant Date Fair Value per Share Number of Shares Weighted-Average Grant Date Fair Value per Share  Nonvested at beginning of period 1,624,934 $ 29.08 1,557,657 $ 29.06  Granted  Restricted stock 826,075 31.74 786,328 31.77  Restricted stock units 15,338 39.12 14,907 39.12  Vested  Restricted stock (819,658) 24.37 (782,505) 24.39  Restricted stock units (13,588) 33.22 (13,233) 33.23  Forfeited - restricted stock (245,504) 35.18 (234,523) 35.17  Nonvested at end of period 1,387,597 $ 32.44 1,328,631 $ 32.41     Year Ended December 31, 2016 CMS Energy, including Consumers Consumers  Granted  Time-lapse awards 188,303 180,958  Market-based awards 185,464 175,818  Performance-based awards 185,464 175,818  Restricted stock units 14,595 14,186  Dividends on market-based awards 38,652 36,646  Dividends on performance-based awards 14,438 13,704  Dividends on restricted stock units 743 721  Additional market-based shares based on achievement of condition 213,754 203,384  Total granted 841,413 801,235 
Schedule of Share-based Payment Award, Restricted Stock, Valuation Assumptions	   Years Ended December 31 2016 2015 2014  Expected volatility 16.7 % 14.1 % 15.6 %  Expected dividend yield 3.2 3.3 3.7  Risk-free rate 1.0 0.8 0.8 
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	   Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Weighted-average grant-date fair value per share  Restricted stock granted $ 31.74 $ 36.84 $ 26.15  Restricted stock units granted 39.12 34.25 -  Consumers  Weighted-average grant-date fair value per share  Restricted stock granted $ 31.77 $ 36.83 $ 26.18  Restricted stock units granted 39.12 34.25 - 
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Fair value of shares that vested during the year $ 31 $ 29 $ 16  Compensation expense recognized 16 20 14  Income tax benefit recognized 7 8 5  Consumers  Fair value of shares that vested during the year $ 30 $ 28 $ 15  Compensation expense recognized 16 19 13  Income tax benefit recognized 6 7 5 
Consumers Energy Company [Member]
Schedule Of Restricted Stock Activity	   CMS Energy, including Consumers Consumers  Year Ended December 31, 2016 Number of Shares Weighted-Average Grant Date Fair Value per Share Number of Shares Weighted-Average Grant Date Fair Value per Share  Nonvested at beginning of period 1,624,934 $ 29.08 1,557,657 $ 29.06  Granted  Restricted stock 826,075 31.74 786,328 31.77  Restricted stock units 15,338 39.12 14,907 39.12  Vested  Restricted stock (819,658) 24.37 (782,505) 24.39  Restricted stock units (13,588) 33.22 (13,233) 33.23  Forfeited - restricted stock (245,504) 35.18 (234,523) 35.17  Nonvested at end of period 1,387,597 $ 32.44 1,328,631 $ 32.41     Year Ended December 31, 2016 CMS Energy, including Consumers Consumers  Granted  Time-lapse awards 188,303 180,958  Market-based awards 185,464 175,818  Performance-based awards 185,464 175,818  Restricted stock units 14,595 14,186  Dividends on market-based awards 38,652 36,646  Dividends on performance-based awards 14,438 13,704  Dividends on restricted stock units 743 721  Additional market-based shares based on achievement of condition 213,754 203,384  Total granted 841,413 801,235 
Schedule of Share-based Payment Award, Restricted Stock, Valuation Assumptions	   Years Ended December 31 2016 2015 2014  Expected volatility 16.7 % 14.1 % 15.6 %  Expected dividend yield 3.2 3.3 3.7  Risk-free rate 1.0 0.8 0.8 
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	   Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Weighted-average grant-date fair value per share  Restricted stock granted $ 31.74 $ 36.84 $ 26.15  Restricted stock units granted 39.12 34.25 -  Consumers  Weighted-average grant-date fair value per share  Restricted stock granted $ 31.77 $ 36.83 $ 26.18  Restricted stock units granted 39.12 34.25 - 
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Fair value of shares that vested during the year $ 31 $ 29 $ 16  Compensation expense recognized 16 20 14  Income tax benefit recognized 7 8 5  Consumers  Fair value of shares that vested during the year $ 30 $ 28 $ 15  Compensation expense recognized 16 19 13  Income tax benefit recognized 6 7 5 

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule Of Effective Income Tax Rate Reconciliation	   In Millions, Except Tax Rate  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Income from continuing operations before income taxes $ 826 $ 796 $ 729   Income tax expense at statutory rate 289 279 255  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 37 39 36  Accelerated flow-through of regulatory tax benefits 1 (39) (39) (39)  Employee share-based awards 2 (7) - -  Other, net (7) (8) (2)  Income tax expense $ 273 $ 271 $ 250  Effective tax rate 33.1 % 34.0 % 34.3 %  Consumers  Income from continuing operations before income taxes $ 936 $ 896 $ 873   Income tax expense at statutory rate 328 314 306  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 44 42 42  Accelerated flow-through of regulatory tax benefits 1 (39) (39) (39)  Employee share-based awards 2 (6) - -  Other, net (7) (15) (3)  Income tax expense $ 320 $ 302 $ 306  Effective tax rate 34.2 % 33.7 % 35.1 %  1 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 $ 39 million for each of the years ended December 31, 2016 , 2015 , and 2014. 2 CMS Energy and Consumers elected to adopt ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , as of January 1, 2016. For further details on the implementation of this standard, see Note 2, New Accounting Standards.
Significant Components Of Income Tax Expense	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Current income taxes  Federal $ - $ - $ -  State and local 9 24 24  $ 9 $ 24 $ 24  Deferred income taxes  Federal $ 200 $ 192 $ 198  State and local 47 36 31  $ 247 $ 228 $ 229  Deferred income tax credit 17 19 (3)  Tax expense $ 273 $ 271 $ 250  Consumers  Current income taxes  Federal $ 9 $ 66 $ 8  State and local 22 32 36  $ 31 $ 98 $ 44  Deferred income taxes  Federal $ 227 $ 153 $ 236  State and local 45 32 29  $ 272 $ 185 $ 265  Deferred income tax credit 17 19 (3)  Tax expense $ 320 $ 302 $ 306 
Principal Components Of Deferred Income Tax Assets And Liailities	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Employee benefits $ (158) $ (127)  Gas inventory (65) (96)  Plant, property, and equipment (2,902) (2,429)  Net regulatory tax liability 27 50  Reserves and accruals 69 59  Securitized costs (118) (122)  Tax loss and credit carryforwards 871 657  Other (6) (5)  $ (2,282) $ (2,013)  Less valuation allowance (5) (4)  Total net deferred income tax liabilities $ (2,287) $ (2,017)  Deferred tax assets, net of valuation reserves $ 962 $ 762  Deferred tax liabilities (3,249) (2,779)  Total net deferred income tax liabilities $ (2,287) $ (2,017)  Consumers  Employee benefits $ (181) $ (156)  Gas inventory (65) (96)  Plant, property, and equipment (2,924) (2,457)  Net regulatory tax liability 27 50  Reserves and accruals 37 30  Securitized costs (118) (122)  Tax loss and credit carryforwards 190 46  Other (8) (5)  Total net deferred income tax liabilities $ (3,042) $ (2,710)  Deferred tax assets, net of valuation reserves $ 254 $ 126  Deferred tax liabilities (3,296) (2,836)  Total net deferred income tax liabilities $ (3,042) $ (2,710) 
Loss And Credit Carryforwards	   In Millions  Gross Amount Tax Attribute Expiration  CMS Energy, including Consumers  Federal net operating loss carryforward $ 1,415 $ 495 2025 – 2036  Local net operating loss carryforwards 408 4 2023 – 2036  Alternative minimum tax credits 270 270 No expiration  General business credits 102 102 2018 – 2036  Total tax attributes $ 871  Consumers  Federal net operating loss carryforward $ 447 $ 157 2025 – 2036  General business credits 33 33 2032 – 2036  Total tax attributes $ 190 
Reconciliation Of Beginning And Ending Uncertain Tax Benefits	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Balance at beginning of period $ 6 $ 5 $ 4  Additions for current-year tax positions - 1 2  Additions for prior-year tax positions - 1 1  Reductions for prior-year tax positions - (1) (2)  Settlements (1) - -  Balance at end of period $ 5 $ 6 $ 5  Consumers  Balance at beginning of period $ 6 $ 5 $ 4  Additions for current-year tax positions - 1 2  Additions for prior-year tax positions - 1 1  Reductions for prior-year tax positions - (1) (2)  Settlements (1) - -  Balance at end of period $ 5 $ 6 $ 5 
Consumers Energy Company [Member]
Schedule Of Effective Income Tax Rate Reconciliation	   In Millions, Except Tax Rate  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Income from continuing operations before income taxes $ 826 $ 796 $ 729   Income tax expense at statutory rate 289 279 255  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 37 39 36  Accelerated flow-through of regulatory tax benefits 1 (39) (39) (39)  Employee share-based awards 2 (7) - -  Other, net (7) (8) (2)  Income tax expense $ 273 $ 271 $ 250  Effective tax rate 33.1 % 34.0 % 34.3 %  Consumers  Income from continuing operations before income taxes $ 936 $ 896 $ 873   Income tax expense at statutory rate 328 314 306  Increase (decrease) in income taxes from:  State and local income taxes, net of federal effect 44 42 42  Accelerated flow-through of regulatory tax benefits 1 (39) (39) (39)  Employee share-based awards 2 (6) - -  Other, net (7) (15) (3)  Income tax expense $ 320 $ 302 $ 306  Effective tax rate 34.2 % 33.7 % 35.1 %  1 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 $ 39 million for each of the years ended December 31, 2016 , 2015 , and 2014. 2 CMS Energy and Consumers elected to adopt ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , as of January 1, 2016. For further details on the implementation of this standard, see Note 2, New Accounting Standards.
Significant Components Of Income Tax Expense	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Current income taxes  Federal $ - $ - $ -  State and local 9 24 24  $ 9 $ 24 $ 24  Deferred income taxes  Federal $ 200 $ 192 $ 198  State and local 47 36 31  $ 247 $ 228 $ 229  Deferred income tax credit 17 19 (3)  Tax expense $ 273 $ 271 $ 250  Consumers  Current income taxes  Federal $ 9 $ 66 $ 8  State and local 22 32 36  $ 31 $ 98 $ 44  Deferred income taxes  Federal $ 227 $ 153 $ 236  State and local 45 32 29  $ 272 $ 185 $ 265  Deferred income tax credit 17 19 (3)  Tax expense $ 320 $ 302 $ 306 
Principal Components Of Deferred Income Tax Assets And Liailities	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Employee benefits $ (158) $ (127)  Gas inventory (65) (96)  Plant, property, and equipment (2,902) (2,429)  Net regulatory tax liability 27 50  Reserves and accruals 69 59  Securitized costs (118) (122)  Tax loss and credit carryforwards 871 657  Other (6) (5)  $ (2,282) $ (2,013)  Less valuation allowance (5) (4)  Total net deferred income tax liabilities $ (2,287) $ (2,017)  Deferred tax assets, net of valuation reserves $ 962 $ 762  Deferred tax liabilities (3,249) (2,779)  Total net deferred income tax liabilities $ (2,287) $ (2,017)  Consumers  Employee benefits $ (181) $ (156)  Gas inventory (65) (96)  Plant, property, and equipment (2,924) (2,457)  Net regulatory tax liability 27 50  Reserves and accruals 37 30  Securitized costs (118) (122)  Tax loss and credit carryforwards 190 46  Other (8) (5)  Total net deferred income tax liabilities $ (3,042) $ (2,710)  Deferred tax assets, net of valuation reserves $ 254 $ 126  Deferred tax liabilities (3,296) (2,836)  Total net deferred income tax liabilities $ (3,042) $ (2,710) 
Loss And Credit Carryforwards	   In Millions  Gross Amount Tax Attribute Expiration  CMS Energy, including Consumers  Federal net operating loss carryforward $ 1,415 $ 495 2025 – 2036  Local net operating loss carryforwards 408 4 2023 – 2036  Alternative minimum tax credits 270 270 No expiration  General business credits 102 102 2018 – 2036  Total tax attributes $ 871  Consumers  Federal net operating loss carryforward $ 447 $ 157 2025 – 2036  General business credits 33 33 2032 – 2036  Total tax attributes $ 190 
Reconciliation Of Beginning And Ending Uncertain Tax Benefits	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Balance at beginning of period $ 6 $ 5 $ 4  Additions for current-year tax positions - 1 2  Additions for prior-year tax positions - 1 1  Reductions for prior-year tax positions - (1) (2)  Settlements (1) - -  Balance at end of period $ 5 $ 6 $ 5  Consumers  Balance at beginning of period $ 6 $ 5 $ 4  Additions for current-year tax positions - 1 2  Additions for prior-year tax positions - 1 1  Reductions for prior-year tax positions - (1) (2)  Settlements (1) - -  Balance at end of period $ 5 $ 6 $ 5 

Earnings Per Share - CMS Ener50

Earnings Per Share - CMS Energy (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share - CMS Energy [Abstract]
Basic And Diluted EPS Computations	   In Millions, Except Per Share Amounts  Years Ended December 31 2016 2015 2014  Income available to common stockholders  Net income $ 553 $ 525 $ 479  Less income attributable to noncontrolling interests 2 2 2  Net income available to common stockholders – basic and diluted $ 551 $ 523 $ 477  Average common shares outstanding  Weighted-average shares – basic 277.9 275.6 270.6  Add dilutive contingently convertible securities - - 3.1  Add dilutive nonvested stock awards 1.0 0.9 0.9  Weighted-average shares – diluted 278.9 276.5 274.6  Net income per average common share available to common stockholders  Basic $ 1.99 $ 1.90 $ 1.76  Diluted 1.98 1.89 1.74   Dividends declared per common share $ 1.24 $ 1.16 $ 1.08 

Other Income and Other Expense

Other Income and Other Expense (Tables)	12 Months Ended
	Dec. 31, 2016
Components Of Other Income And Other Expense	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Other income  Fee income $ 6 $ 9 $ 8  All other 2 1 3  Total other income – CMS Energy $ 8 $ 10 $ 11  Consumers  Other income  Fee income $ 6 $ 9 $ 8  Gain on CMS Energy common stock - 9 -  All other 2 1 2  Total other income – Consumers $ 8 $ 19 $ 10  CMS Energy, including Consumers  Other expense  Civic and political expenditures $ (21) $ (10) $ (14)  Donations (23) (1) (15)  Loss on reacquired and extinguished debt (18) - (20)  Unrealized investment loss (5) - -  All other (8) (6) (6)  Total other expense – CMS Energy $ (75) $ (17) $ (55)  Consumers  Other expense  Civic and political expenditures $ (21) $ (10) $ (14)  Donations (23) (1) (15)  Unrealized investment loss (4) - -  All other (7) (6) (6)  Total other expense – Consumers $ (55) $ (17) $ (35) 
Consumers Energy Company [Member]
Components Of Other Income And Other Expense	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Other income  Fee income $ 6 $ 9 $ 8  All other 2 1 3  Total other income – CMS Energy $ 8 $ 10 $ 11  Consumers  Other income  Fee income $ 6 $ 9 $ 8  Gain on CMS Energy common stock - 9 -  All other 2 1 2  Total other income – Consumers $ 8 $ 19 $ 10  CMS Energy, including Consumers  Other expense  Civic and political expenditures $ (21) $ (10) $ (14)  Donations (23) (1) (15)  Loss on reacquired and extinguished debt (18) - (20)  Unrealized investment loss (5) - -  All other (8) (6) (6)  Total other expense – CMS Energy $ (75) $ (17) $ (55)  Consumers  Other expense  Civic and political expenditures $ (21) $ (10) $ (14)  Donations (23) (1) (15)  Unrealized investment loss (4) - -  All other (7) (6) (6)  Total other expense – Consumers $ (55) $ (17) $ (35) 

Cash And Cash Equivalents (Tabl

Cash And Cash Equivalents (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule Of Cash And Cash Equivalents, Including Restricted Amounts	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Cash and cash equivalents $ 235 $ 266  Restricted cash and cash equivalents 19 19  Other non-current assets 3 3  Cash and cash equivalents, including restricted amounts $ 257 $ 288  Consumers  Cash and cash equivalents $ 131 $ 50  Restricted cash and cash equivalents 19 19  Other non-current assets 2 2  Cash and cash equivalents, including restricted amounts $ 152 $ 71 
Consumers Energy Company [Member]
Schedule Of Cash And Cash Equivalents, Including Restricted Amounts	   In Millions  December 31 2016 2015  CMS Energy, including Consumers  Cash and cash equivalents $ 235 $ 266  Restricted cash and cash equivalents 19 19  Other non-current assets 3 3  Cash and cash equivalents, including restricted amounts $ 257 $ 288  Consumers  Cash and cash equivalents $ 131 $ 50  Restricted cash and cash equivalents 19 19  Other non-current assets 2 2  Cash and cash equivalents, including restricted amounts $ 152 $ 71 

Reportable Segments (Tables)

Reportable Segments (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule Of Financial Information By Reportable Segments	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Operating revenue  Electric utility $ 4,379 $ 4,249 $ 4,436  Gas utility 1,685 1,916 2,363  Enterprises 215 190 299  Other reconciling items 120 101 81  Total operating revenue – CMS Energy $ 6,399 $ 6,456 $ 7,179  Consumers  Operating revenue  Electric utility $ 4,379 $ 4,249 $ 4,436  Gas utility 1,685 1,916 2,363  Other reconciling items - - 1  Total operating revenue – Consumers $ 6,064 $ 6,165 $ 6,800  CMS Energy, including Consumers  Depreciation and amortization  Electric utility $ 603 $ 567 $ 522  Gas utility 200 177 156  Enterprises 5 4 4  Other reconciling items 3 2 3  Total depreciation and amortization – CMS Energy $ 811 $ 750 $ 685  Consumers  Depreciation and amortization  Electric utility $ 603 $ 567 $ 522  Gas utility 200 177 156  Total depreciation and amortization – Consumers $ 803 $ 744 $ 678  CMS Energy, including Consumers  Income from equity method investees 1  Enterprises $ 13 $ 14 $ 15  Total income from equity method investees – CMS Energy $ 13 $ 14 $ 15  CMS Energy, including Consumers  Interest charges  Electric utility $ 196 $ 178 $ 181  Gas utility 72 71 67  Enterprises 1 - -  Other reconciling items 166 147 159  Total interest charges – CMS Energy $ 435 $ 396 $ 407  Consumers  Interest charges  Electric utility $ 196 $ 178 $ 181  Gas utility 72 71 67  Other reconciling items - 1 2  Total interest charges – Consumers $ 268 $ 250 $ 250     In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Income tax expense (benefit)  Electric utility $ 246 $ 224 $ 211  Gas utility 74 78 95  Enterprises 10 3 (1)  Other reconciling items (57) (34) (55)  Total income tax expense – CMS Energy $ 273 $ 271 $ 250  Consumers  Income tax expense  Electric utility $ 246 $ 224 $ 211  Gas utility 74 78 95  Total income tax expense – Consumers $ 320 $ 302 $ 306  CMS Energy, including Consumers  Net income (loss) available to common stockholders  Electric utility $ 458 $ 437 $ 384  Gas utility 155 154 179  Enterprises 17 4 (1)  Other reconciling items (79) (72) (85)  Total net income available to common stockholders – CMS Energy $ 551 $ 523 $ 477  Consumers  Net income available to common stockholder  Electric utility $ 458 $ 437 $ 384  Gas utility 155 154 179  Other reconciling items 1 1 2  Total net income available to common stockholder – Consumers $ 614 $ 592 $ 565  CMS Energy, including Consumers  Plant, property, and equipment, gross  Electric utility $ 14,540 $ 13,059 $ 12,230  Gas utility 6,283 5,723 5,335  Enterprises 157 120 115  Other reconciling items 30 41 41  Total plant, property, and equipment, gross – CMS Energy $ 21,010 $ 18,943 $ 17,721  Consumers  Plant, property, and equipment, gross  Electric utility $ 14,540 $ 13,059 $ 12,230  Gas utility 6,283 5,723 5,335  Other reconciling items 15 15 15  Total plant, property, and equipment, gross – Consumers $ 20,838 $ 18,797 $ 17,580  CMS Energy, including Consumers  Investments in equity method investees 1  Enterprises $ 62 $ 61 $ 58  Other reconciling items 3 3 3  Total investments in equity method investees – CMS Energy $ 65 $ 64 $ 61     In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Total assets  Electric utility 2 $ 13,429 $ 12,660 $ 11,565  Gas utility 2 6,446 5,912 5,385  Enterprises 269 270 231  Other reconciling items 1,478 1,457 1,962  Total assets – CMS Energy $ 21,622 $ 20,299 $ 19,143  Consumers  Total assets  Electric utility 2 $ 13,430 $ 12,660 $ 11,565  Gas utility 2 6,446 5,912 5,385  Other reconciling items 70 63 874  Total assets – Consumers $ 19,946 $ 18,635 $ 17,824  CMS Energy, including Consumers  Capital expenditures 3  Electric utility $ 1,007 $ 1,136 $ 1,139  Gas utility 611 558 473  Enterprises 10 44 3  Other reconciling items 5 3 1  Total capital expenditures – CMS Energy $ 1,633 $ 1,741 $ 1,616  Consumers  Capital expenditures 3  Electric utility $ 1,007 $ 1,136 $ 1,139  Gas utility 611 558 473  Total capital expenditures – Consumers $ 1,618 $ 1,694 $ 1,612  1 Consumers had no significant equity method investments. 2 Amounts include a portion of Consumers’ other common assets attributable to both the electric and gas utility businesses. 3 Amounts include purchase of capital lease additions. Amounts also include a portion of Consumers’ capital expenditures for plant and equipment attributable to both the electric and gas utility businesses.
Consumers Energy Company [Member]
Schedule Of Financial Information By Reportable Segments	   In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Operating revenue  Electric utility $ 4,379 $ 4,249 $ 4,436  Gas utility 1,685 1,916 2,363  Enterprises 215 190 299  Other reconciling items 120 101 81  Total operating revenue – CMS Energy $ 6,399 $ 6,456 $ 7,179  Consumers  Operating revenue  Electric utility $ 4,379 $ 4,249 $ 4,436  Gas utility 1,685 1,916 2,363  Other reconciling items - - 1  Total operating revenue – Consumers $ 6,064 $ 6,165 $ 6,800  CMS Energy, including Consumers  Depreciation and amortization  Electric utility $ 603 $ 567 $ 522  Gas utility 200 177 156  Enterprises 5 4 4  Other reconciling items 3 2 3  Total depreciation and amortization – CMS Energy $ 811 $ 750 $ 685  Consumers  Depreciation and amortization  Electric utility $ 603 $ 567 $ 522  Gas utility 200 177 156  Total depreciation and amortization – Consumers $ 803 $ 744 $ 678  CMS Energy, including Consumers  Income from equity method investees 1  Enterprises $ 13 $ 14 $ 15  Total income from equity method investees – CMS Energy $ 13 $ 14 $ 15  CMS Energy, including Consumers  Interest charges  Electric utility $ 196 $ 178 $ 181  Gas utility 72 71 67  Enterprises 1 - -  Other reconciling items 166 147 159  Total interest charges – CMS Energy $ 435 $ 396 $ 407  Consumers  Interest charges  Electric utility $ 196 $ 178 $ 181  Gas utility 72 71 67  Other reconciling items - 1 2  Total interest charges – Consumers $ 268 $ 250 $ 250     In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Income tax expense (benefit)  Electric utility $ 246 $ 224 $ 211  Gas utility 74 78 95  Enterprises 10 3 (1)  Other reconciling items (57) (34) (55)  Total income tax expense – CMS Energy $ 273 $ 271 $ 250  Consumers  Income tax expense  Electric utility $ 246 $ 224 $ 211  Gas utility 74 78 95  Total income tax expense – Consumers $ 320 $ 302 $ 306  CMS Energy, including Consumers  Net income (loss) available to common stockholders  Electric utility $ 458 $ 437 $ 384  Gas utility 155 154 179  Enterprises 17 4 (1)  Other reconciling items (79) (72) (85)  Total net income available to common stockholders – CMS Energy $ 551 $ 523 $ 477  Consumers  Net income available to common stockholder  Electric utility $ 458 $ 437 $ 384  Gas utility 155 154 179  Other reconciling items 1 1 2  Total net income available to common stockholder – Consumers $ 614 $ 592 $ 565  CMS Energy, including Consumers  Plant, property, and equipment, gross  Electric utility $ 14,540 $ 13,059 $ 12,230  Gas utility 6,283 5,723 5,335  Enterprises 157 120 115  Other reconciling items 30 41 41  Total plant, property, and equipment, gross – CMS Energy $ 21,010 $ 18,943 $ 17,721  Consumers  Plant, property, and equipment, gross  Electric utility $ 14,540 $ 13,059 $ 12,230  Gas utility 6,283 5,723 5,335  Other reconciling items 15 15 15  Total plant, property, and equipment, gross – Consumers $ 20,838 $ 18,797 $ 17,580  CMS Energy, including Consumers  Investments in equity method investees 1  Enterprises $ 62 $ 61 $ 58  Other reconciling items 3 3 3  Total investments in equity method investees – CMS Energy $ 65 $ 64 $ 61     In Millions  Years Ended December 31 2016 2015 2014  CMS Energy, including Consumers  Total assets  Electric utility 2 $ 13,429 $ 12,660 $ 11,565  Gas utility 2 6,446 5,912 5,385  Enterprises 269 270 231  Other reconciling items 1,478 1,457 1,962  Total assets – CMS Energy $ 21,622 $ 20,299 $ 19,143  Consumers  Total assets  Electric utility 2 $ 13,430 $ 12,660 $ 11,565  Gas utility 2 6,446 5,912 5,385  Other reconciling items 70 63 874  Total assets – Consumers $ 19,946 $ 18,635 $ 17,824  CMS Energy, including Consumers  Capital expenditures 3  Electric utility $ 1,007 $ 1,136 $ 1,139  Gas utility 611 558 473  Enterprises 10 44 3  Other reconciling items 5 3 1  Total capital expenditures – CMS Energy $ 1,633 $ 1,741 $ 1,616  Consumers  Capital expenditures 3  Electric utility $ 1,007 $ 1,136 $ 1,139  Gas utility 611 558 473  Total capital expenditures – Consumers $ 1,618 $ 1,694 $ 1,612  1 Consumers had no significant equity method investments. 2 Amounts include a portion of Consumers’ other common assets attributable to both the electric and gas utility businesses. 3 Amounts include purchase of capital lease additions. Amounts also include a portion of Consumers’ capital expenditures for plant and equipment attributable to both the electric and gas utility businesses.

Related Party Transactions - 54

Related Party Transactions - Consumers (Tables)	12 Months Ended
	Dec. 31, 2016
Consumers Energy Company [Member]
Schedule of Related Party Transactions, by Related Party Table	   In Millions  Description Related Party 2016 2015 2014  Purchases of capacity and energy Affiliates of CMS Enterprises $ 88 $ 83 $ 89 

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2016
Variable Interest Entities [Abstract]
Schedule Of Variable Interest Entities	   Name (Ownership Interest) Nature of the Entity Financing of Partnership  T.E.S. Filer City ( 50% ) Coal-fueled power generator Line of credit secured by T.E.S. Filer City’s coal inventory   Grayling ( 50% ) Wood waste-fueled power generator Line of credit secured by specific assets of Grayling. This line of credit expired in 2016.   Genesee ( 50% ) Wood waste-fueled power generator Sale of revenue bonds that mature in 2021 and bear interest at fixed rates. The debt is non-recourse to the partners and secured by a CMS Energy guarantee capped at $3 million annually.   Craven ( 50% ) Wood waste-fueled power generator Line of credit secured by Craven’s property, plant, and equipment 

Quarterly Financial And Commo56

Quarterly Financial And Common Stock Information (Tables)	12 Months Ended
	Dec. 31, 2016
Schedule of Quarterly Financial Information Table	   In Millions, Except Per Share Amounts and Stock Prices  2016  Quarters Ended March 31 June 30 Sept 30 Dec 31  CMS Energy, including Consumers  Operating revenue $ 1,801 $ 1,371 $ 1,587 $ 1,640  Operating income 336 285 386 290  Net income 164 125 186 78  Income attributable to noncontrolling interests - 1 - 1  Net income available to common stockholders 164 124 186 77  Basic earnings per average common share 1 0.59 0.45 0.67 0.28  Diluted earnings per average common share 1 0.59 0.45 0.67 0.28  Common stock prices 2  High 42.44 45.86 46.17 42.15  Low 35.61 39.38 41.31 39.49  Consumers  Operating revenue $ 1,723 $ 1,293 $ 1,498 $ 1,550  Operating income 317 264 365 288  Net income 172 132 195 117  Preferred stock dividends - 1 - 1  Net income available to common stockholder 172 131 195 116     In Millions, Except Per Share Amounts and Stock Prices  2015  Quarters Ended March 31 June 30 Sept 30 Dec 31  CMS Energy, including Consumers  Operating revenue $ 2,111 $ 1,350 $ 1,486 $ 1,509  Operating income 397 204 317 245  Net income 202 68 148 107  Income attributable to noncontrolling interests - 1 - 1  Net income available to common stockholders 202 67 148 106  Basic earnings per average common share 1 0.73 0.25 0.53 0.39  Diluted earnings per average common share 1 0.73 0.25 0.53 0.38  Common stock prices 2  High 38.20 35.57 35.82 37.17  Low 32.83 31.39 32.10 34.24  Consumers  Operating revenue $ 2,028 $ 1,281 $ 1,417 $ 1,439  Operating income 379 192 305 246  Net income 215 84 160 135  Preferred stock dividends - 1 - 1  Net income available to common stockholder 215 83 160 134  1 The sum of the quarters may not equal annual EPS due to changes in the number of shares outstanding. 2 Based on New York Stock Exchange composite transactions.
Consumers Energy Company [Member]
Schedule of Quarterly Financial Information Table	   In Millions, Except Per Share Amounts and Stock Prices  2016  Quarters Ended March 31 June 30 Sept 30 Dec 31  CMS Energy, including Consumers  Operating revenue $ 1,801 $ 1,371 $ 1,587 $ 1,640  Operating income 336 285 386 290  Net income 164 125 186 78  Income attributable to noncontrolling interests - 1 - 1  Net income available to common stockholders 164 124 186 77  Basic earnings per average common share 1 0.59 0.45 0.67 0.28  Diluted earnings per average common share 1 0.59 0.45 0.67 0.28  Common stock prices 2  High 42.44 45.86 46.17 42.15  Low 35.61 39.38 41.31 39.49  Consumers  Operating revenue $ 1,723 $ 1,293 $ 1,498 $ 1,550  Operating income 317 264 365 288  Net income 172 132 195 117  Preferred stock dividends - 1 - 1  Net income available to common stockholder 172 131 195 116     In Millions, Except Per Share Amounts and Stock Prices  2015  Quarters Ended March 31 June 30 Sept 30 Dec 31  CMS Energy, including Consumers  Operating revenue $ 2,111 $ 1,350 $ 1,486 $ 1,509  Operating income 397 204 317 245  Net income 202 68 148 107  Income attributable to noncontrolling interests - 1 - 1  Net income available to common stockholders 202 67 148 106  Basic earnings per average common share 1 0.73 0.25 0.53 0.39  Diluted earnings per average common share 1 0.73 0.25 0.53 0.38  Common stock prices 2  High 38.20 35.57 35.82 37.17  Low 32.83 31.39 32.10 34.24  Consumers  Operating revenue $ 2,028 $ 1,281 $ 1,417 $ 1,439  Operating income 379 192 305 246  Net income 215 84 160 135  Preferred stock dividends - 1 - 1  Net income available to common stockholder 215 83 160 134  1 The sum of the quarters may not equal annual EPS due to changes in the number of shares outstanding. 2 Based on New York Stock Exchange composite transactions.

Significant Accounting Polici57

Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2016
Minimum [Member] | EnerBank [Member]
Significant Accounting Policies [Line Items]
Same as cash, fee recognition period	3 months
Authorized contractor, fee recognition period	1 year
Maximum [Member] | Consumers Energy Company [Member]
Significant Accounting Policies [Line Items]
Financial incentive as percentage of energy optimization program spending	15.00%
Energy optimization spending limit	2.00%
Maximum [Member] | EnerBank [Member]
Significant Accounting Policies [Line Items]
Same as cash, fee recognition period	24 months
Authorized contractor, fee recognition period	12 years

New Accounting Standards (Detai

New Accounting Standards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2014	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unamortized debt issuance costs	$ 45		$ 41
Cumulative effect of change in accounting principle	33
Debt retirement premium payments	18	$ 36
New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess tax benefit related to stock	7
Debt retirement premium payments		36
Retained Earnings (Accumulated Deficit) [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle	33
CMS Energy [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt retirement premium payments	18	20
Consumers Energy Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unamortized debt issuance costs	25		$ 23
Debt retirement premium payments		16
Consumers Energy Company [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess tax benefit related to stock	$ 7
Debt retirement premium payments		$ 16

New Accounting Standards (Sched

New Accounting Standards (Schedule Of Restricted Cash Balances) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	$ 288	$ 249	$ 204
Cash from investing	(1,915)	(2,064)	(1,898)
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	257	288	249
CMS Energy [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period
Cash from investing	(275)	(150)	(317)
Cash and Cash Equivalents, Including Restricted Amounts, End of Period
Consumers Energy Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	71	112	49
Cash from investing	(1,768)	(1,801)	(1,643)
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	152	71	112
New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	22	42	32
Cash from investing		(20)	10
Cash and Cash Equivalents, Including Restricted Amounts, End of Period		22	42
New Accounting Pronouncement, Early Adoption, Effect [Member] | Consumers Energy Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	$ 21	41	31
Cash from investing		(20)	10
Cash and Cash Equivalents, Including Restricted Amounts, End of Period		$ 21	$ 41

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) $ in Millions	1 Months Ended									3 Months Ended								12 Months Ended
	Oct. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Apr. 30, 2016USD ($)itemsite	Mar. 31, 2016USD ($)	Jan. 31, 2016USD ($)	Nov. 30, 2015USD ($)	Jul. 31, 2015USD ($)	Jun. 30, 2015USD ($)site	Dec. 31, 2014USD ($)	Dec. 31, 2016USD ($)site	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2016USD ($)site	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Public Utilities, General Disclosures [Line Items]
Revenue										$ 1,640	$ 1,587	$ 1,371	$ 1,801	$ 1,509	$ 1,486	$ 1,350	$ 2,111	$ 6,399		$ 6,456		$ 7,179
Regulatory liability current										95				82				95		82
Accrued rate refunds										21				26				21		26
Cost of gas sold																		710		961		1,493
Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Income tax benefits returned to customers																		64
Revenue										1,550	1,498	1,293	1,723	1,439	$ 1,417	$ 1,281	2,028	6,064		6,165		6,800
Regulatory liability current										95				82				$ 95		82
Number of units retired | site																		10
Accrued rate refunds										21				26				$ 21		26
Cost of gas sold																		693		939		1,375
Coal-Fueled Electric Generation [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Number of units retired | site			7
Gas-Fueled Electric Generation [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Number of units retired | site								3
Electric Utility [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Income tax benefits, to be returned to customers																		$ 209
Tax benefit, distribution to customers, term																		5 years
Gas Utility [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Income tax benefits, to be returned to customers																		$ 260
Tax benefit, distribution to customers, term																		12 years
Gas Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested							$ 85
Rate of return on equity requested							10.70%
Annual rate increase self-implemented					$ 60
Annual rate increase authorized			$ 40
Gas Cost Recover (GCR) [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Over (under) recovery requested				$ 2									$ 2						$ 2
Accrued rate refunds										13				18				$ 13		18
Over (under) recovery authorized by the MPSC																	$ 9				$ 9		$ (84)
Cost of gas sold																			$ 500		$ 800		$ 900
Power Supply Cost Recover (PSCR) [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Over (under) recovery requested														6						6
Litigation costs																		6
Accrued rate refunds										8				8				8		8
PSCR Cost of Power Sold																				1,900		2,100		$ 1,900
Over (under) recovery authorized by the MPSC									$ 5													$ 5		9
Energy Optimization [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Authorized recovery/collection		$ 18									$ 18
Revenue																		18		18
Requested recovery/collection										$ 18								$ 18
2014 Electric Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Number of units retired | item			7
Annual rate increase requested									$ 163
Annual rate increase self-implemented								$ 110
Annual rate increase authorized			$ 126
Rate of return on equity authorized						10.30%
Temporary rate increase						$ 165
2016 Electric Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Amended Annual Rate Increase Request	$ 208
Annual rate increase requested				$ 225
Rate of return on equity requested				10.70%
Annual rate increase self-implemented		$ 170
Investment recovery, 2017				$ 38
Investment recovery, 2018				92
Investment recovery, 2019				$ 92
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Authorized recovery, collection period																		10 years
Number of former MGPs | site										23								23
Gas Storage Inventory Adjustments [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Authorized recovery, collection period																		5 years
Renewable Energy Grant [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from government grant																								$ 69
Revenue Subject To Refund [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability current										$ 31				18				$ 31		18
Revenue Subject To Refund [Member] | Gas Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability current										$ 10								$ 10
Revenue Subject To Refund [Member] | 2014 Electric Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability current												$ 1
Revenue Subject To Refund [Member] | Securitized Costs [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liability current														$ 14						$ 14

Regulatory Matters (Schedule Of

Regulatory Matters (Schedule Of The Components Of Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Public Utilities, General Disclosures [Line Items]
Regulatory assets, current		$ 17	$ 16
Regulatory assets, noncurrent		2,091	1,840
Regulatory liabilities, current		95	82
Regulatory liabilities, noncurrent		2,041	2,088
Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, current		17	16
Regulatory assets, noncurrent		2,091	1,840
Total regulatory asset		2,108	1,856
Regulatory liabilities, current		95	82
Regulatory liabilities, noncurrent		2,041	2,088
Total regulatory liabilities		2,136	2,170
Cost Of Removal [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities, noncurrent		$ 1,809	1,745
Renewable Energy Plan [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Liability, Recovery End Date		2,028
Regulatory liabilities, noncurrent		$ 83	109
Income Taxes, Net [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Current Regulatory Liability Recovery End Date		2,017
Regulatory liabilities, current		$ 64	64
Regulatory liabilities, noncurrent		7	64
ARO [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities, noncurrent		$ 62	73
Renewable Energy Grant [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Liability, Recovery End Date		2,043
Regulatory liabilities, noncurrent		$ 58	60
Energy Optimization [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Asset Recovery End Date		2,018
Regulatory assets, noncurrent		$ 18	18
Regulatory liabilities, noncurrent		11	26
Other Regulatory Assets [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities, noncurrent		$ 11	11
Revenue Subject To Refund [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Current Regulatory Liability Recovery End Date		2,017
Regulatory liabilities, current		$ 31	18
Postretirement Benefits [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	[1]	$ 1,373	1,096
Securitized Costs [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Noncurrent Regulatory Asset Recovery End Date	[2]	2,029
Regulatory assets, noncurrent	[2]	$ 323	348
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	[1]	139	146
ARO [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		166	151
Unamortized Loss On Reacquired Debt [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		54	61
Gas Storage Inventory Adjustments [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent	[3]	$ 14	18
Energy Optimization [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Current Asset, End Date for Recovery	[4]	2,017
Regulatory assets, current	[4]	$ 17	16
Other Regulatory Assets [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		$ 4	$ 2
[1]	The MPSC has authorized a specific return on this regulatory asset.
[2]	This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return.
[3]	These regulatory assets represent incurred costs for which the MPSC has provided, or Consumers expects, recovery without a return on investment.
[4]	These regulatory assets have arisen from an alternative revenue program and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return.

Regulatory Matters (Schedule 62

Regulatory Matters (Schedule of Components of the Annual Rate Increase Requested) (Details) - 2016 Electric Rate Case [Member] - Consumers Energy Company [Member] $ in Millions	1 Months Ended
	Mar. 31, 2016USD ($)
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested	$ 225
Investment In Rate Base [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested	161
Operating And Maintenance Costs [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested	21
Gross Margin [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested	17
Cost Of Capital [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested	15
Working Capital [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested	$ 11

Regulatory Matters (Schedule 63

Regulatory Matters (Schedule Of The Components Of PSCR And GCR Over/(Under) Recoveries) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	$ 21	$ 26
Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	21	26
Consumers Energy Company [Member] | Power Supply Cost Recover (PSCR) [Member]
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	8	8
Consumers Energy Company [Member] | Gas Cost Recover (GCR) [Member]
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	$ 13	$ 18

Contingencies And Commitments64

Contingencies And Commitments (Contingencies And Commitments) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)lawsuitsite	Dec. 31, 2015USD ($)
Loss Contingencies [Line Items]
Number of lawsuits settled | lawsuit	3
Increase due to change in estimate		$ 74
Regulatory assets	$ 2,091	1,840
Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Increase due to change in estimate		74
Regulatory assets	2,091	$ 1,840
Bay Harbor [Member]
Loss Contingencies [Line Items]
Demand for payment by USEPA	8
Accrual for environmental loss contingencies	$ 51
Discounted projected costs rate	4.34%
Remaining undiscounted obligation amount	$ 65
Accrual for environmental loss contingencies, inflation rate	1.00%
CERCLA Liability [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 3
CERCLA Liability [Member] | Minimum [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Remediation and other response activity costs	3
CERCLA Liability [Member] | Maximum [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Remediation and other response activity costs	8
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 107
Discounted projected costs rate	2.57%
Remaining undiscounted obligation amount	$ 117
Number of former MGPs | site	23
Regulatory assets	$ 139
Authorized recovery, collection period	10 years
Accrual for environmental loss contingencies, inflation rate	2.50%
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
Gas Utility [Member] | NREPA [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	1
Gas Utility [Member] | NREPA [Member] | Maximum [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Remediation and other response activity costs	3
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
Number of lawsuits pending | lawsuit	2
Individual Lawsuits [Member]
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit	1

Contingencies And Commitments65

Contingencies And Commitments (Expected Remediation Cost By Year) (Details) $ in Millions	Dec. 31, 2016USD ($)
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Site Contingency [Line Items]
Undiscounted amount due in next fiscal year	$ 35
Undiscounted amount due within two year	14
Undiscounted amount due within third year	19
Undiscounted amount due within fourth year	10
Undiscounted amount due within five year	5
Bay Harbor [Member]
Site Contingency [Line Items]
Undiscounted amount due in next fiscal year	5
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

Contingencies And Commitments66

Contingencies And Commitments (Guarantees) (Details) $ in Millions		1 Months Ended	12 Months Ended
		Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)$ / MWhMW	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Guarantees And Other Contingencies [Line Items]
PPE reduction resulting from tax refund			$ 34
Income Tax Settlement [Member]
Guarantees And Other Contingencies [Line Items]
Reduction of income tax expense			3
General Taxes [Member]
Guarantees And Other Contingencies [Line Items]
Reduction of income tax expense			$ 3
Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Expiration Date	[1]		Indefinite
Maximum obligation	[1]		$ 30
Consumers Energy Company [Member] | Settlement with Taxing Authority [Member]
Guarantees And Other Contingencies [Line Items]
Tax examination refund		$ 60		$ 37
Tax refund received		13
Note receivable in 2017		30
Note receivable, in 2018		17
Gain (loss) related to tax settlement			$ 4
Consumers Energy Company [Member] | Interest Expense [Member] | Settlement with Taxing Authority [Member]
Guarantees And Other Contingencies [Line Items]
Tax examination refund				12
Consumers Energy Company [Member] | Interest Income [Member] | Settlement with Taxing Authority [Member]
Guarantees And Other Contingencies [Line Items]
Tax examination refund				6
Consumers Energy Company [Member] | General Taxes [Member] | Settlement with Taxing Authority [Member]
Guarantees And Other Contingencies [Line Items]
Tax examination refund				5
Consumers Energy Company [Member] | Refund Of Taxes Paid Receivable [Member] | Settlement with Taxing Authority [Member]
Guarantees And Other Contingencies [Line Items]
Tax examination refund		42
Consumers Energy Company [Member] | Refund Of Interest Paid Receivable [Member] | Settlement with Taxing Authority [Member]
Guarantees And Other Contingencies [Line Items]
Tax examination refund		12
Consumers Energy Company [Member] | Interest Receivable [Member] | Settlement with Taxing Authority [Member]
Guarantees And Other Contingencies [Line Items]
Tax examination refund		$ 6
Consumers Energy Company [Member] | Plant, Property, And Equipment [Member] | Settlement with Taxing Authority [Member]
Guarantees And Other Contingencies [Line Items]
Tax examination refund				19
Guarantees [Member]
Guarantees And Other Contingencies [Line Items]
Expiration Date	[1]		Indefinite
Maximum obligation	[1]		$ 48
Indemnity Obligations From Stock And Asset Sales Agreements [Member]
Guarantees And Other Contingencies [Line Items]
Expiration Date	[2]		Indefinite
Maximum obligation	[2]		$ 153
Carrying Amount	[2]		7
Tax And Other Indemnity Obligations [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Carrying Amount			1
MCV PPA [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Purchase Obligations Total			3,010
Purchase Obligations Due in Year One			326
Purchase Obligations Due in Year Two			331
Purchase Obligations Due in Year Three			330
Purchase Obligations Due in Year Four			344
Purchase Obligations Due in Year Five			325
Purchase Obligations Due After Year Five			$ 1,354
Term of Unrecorded Unconditional Purchase Obligations			35 years
Unrecorded Unconditional Purchase Obligations, Minimum Quantity Required | MW			1,240
Unrecorded Unconditional Purchase Obligation Capacity Charge Per Mwh | $ / MWh			10.14
Unrecorded Unconditional Purchase Obligation, Annual Contribution to Renewable Resources Program By Counterparty			$ 5
Unrecorded Unconditional Purchase Obligation, Contract Extension Period			5 years
Unrecorded Unconditional Purchase Obligation, Purchases			$ 305	282	$ 300
Palisades PPA [Member]
Guarantees And Other Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligations, Maximum Quantity | MW			798
Palisades PPA [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Purchase Obligations Total			$ 1,994
Purchase Obligations Due in Year One			354
Purchase Obligations Due in Year Two			365
Purchase Obligations Due in Year Three			376
Purchase Obligations Due in Year Four			388
Purchase Obligations Due in Year Five			398
Purchase Obligations Due After Year Five			113
Unrecorded Unconditional Purchase Obligation, Purchases			$ 363	352	302
Unrecorded Unconditional Purchase Obligations, Maximum Quantity | MW			798
Related Parties PPA [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Purchase Obligations Total			$ 899
Purchase Obligations Due in Year One			81
Purchase Obligations Due in Year Two			82
Purchase Obligations Due in Year Three			86
Purchase Obligations Due in Year Four			88
Purchase Obligations Due in Year Five			88
Purchase Obligations Due After Year Five			474
Other PPA [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Purchase Obligations Total			3,453
Purchase Obligations Due in Year One			247
Purchase Obligations Due in Year Two			253
Purchase Obligations Due in Year Three			229
Purchase Obligations Due in Year Four			231
Purchase Obligations Due in Year Five			233
Purchase Obligations Due After Year Five			2,260
Unrecorded Unconditional Purchase Obligation, Purchases			348	$ 347	$ 354
PPA [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Purchase Obligations Total			9,356
Purchase Obligations Due in Year One			1,008
Purchase Obligations Due in Year Two			1,031
Purchase Obligations Due in Year Three			1,021
Purchase Obligations Due in Year Four			1,051
Purchase Obligations Due in Year Five			1,044
Purchase Obligations Due After Year Five			4,201
Other Purchase Obligations [Member]
Guarantees And Other Contingencies [Line Items]
Purchase Obligations Total			1,922
Purchase Obligations Due in Year One			931
Purchase Obligations Due in Year Two			376
Purchase Obligations Due in Year Three			187
Purchase Obligations Due in Year Four			132
Purchase Obligations Due in Year Five			32
Purchase Obligations Due After Year Five			264
Other Purchase Obligations [Member] | Consumers Energy Company [Member]
Guarantees And Other Contingencies [Line Items]
Purchase Obligations Total			1,651
Purchase Obligations Due in Year One			895
Purchase Obligations Due in Year Two			347
Purchase Obligations Due in Year Three			157
Purchase Obligations Due in Year Four			102
Purchase Obligations Due in Year Five			19
Purchase Obligations Due After Year Five			$ 131
[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. For additional details on this guarantee, see Note 20, Variable Interest Entities.
[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 Capitalization67

Financings And Capitalization (Narrative) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Financing And Capitalization [Line Items]
Debt issuance		$ 1,025,000,000
Limitation on payment of stock dividends		4,300,000,000
Common stock dividends from Consumers		$ 499,000,000
Common stock, shares authorized		350,000,000	350,000,000
Par value of Common Stock		$ 0.01
Shares of Preferred Stock authorized		10,000,000
Par value of Preferred Stock		$ 0.01
Aggregate sales price of an equity offering program		$ 100,000,000
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		$ 575,000,000
Consumers Energy Company [Member]
Financing And Capitalization [Line Items]
Debt issuance		450,000,000
Maximum allowed short term securities outstanding under FERC Authorization		800,000,000
Maximum allowed long-term securites outstanding under FERC Authorization		1,800,000,000
Long-term securities, remaining availability under FERC Authorization		1,300,000,000
Short-term debt, authorized borrowings		800,000,000
Short-term borrowings outstanding		398,000,000
Unrestricted retained earnings		$ 1,000,000,000
Common stock, shares authorized		125,000,000	125,000,000
Consumers Energy Company [Member] | Commercial Paper [Member]
Financing And Capitalization [Line Items]
Weighted average annual interest rate		1.14%
Short-term debt, authorized borrowings		$ 500,000,000
Short-term borrowings outstanding		398,000,000
Revolving Credit Facilities May 27, 2021 [Member]
Financing And Capitalization [Line Items]
Amount of Facility	[1],[2]	550,000,000
Revolving Credit Facilities May 27, 2021 [Member] | Consumers Energy Company [Member]
Financing And Capitalization [Line Items]
Amount of Facility	[2],[3]	$ 650,000,000
[1]	During the year ended December 31, 2016, CMS Energy's average borrowings totaled $3 million with a weighted-average interest rate of 1.68 percent. Obligations under this facility are secured by Consumers common stock.
[2]	In May 2016, the expiration date of this revolving credit agreement was extended from 2020 to 2021.
[3]	Obligations under this facility are secured by first mortgage bonds of Consumers.

Financings and Capitalization68

Financings and Capitalization (Summary of Long-Term Debt Outstanding) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Principal amounts outstanding		$ 9,564,000,000	$ 9,137,000,000
Current portion of long-term debt		(864,000,000)	(684,000,000)
Net unamortized discounts		(15,000,000)	(12,000,000)
Unamortized debt issuance costs		(45,000,000)	(41,000,000)
Total long-term debt		8,640,000,000	8,400,000,000
Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal amounts outstanding		5,661,000,000	5,409,000,000
Current portion of long-term debt		(375,000,000)	(198,000,000)
Net unamortized discounts		(8,000,000)	(5,000,000)
Unamortized debt issuance costs		(25,000,000)	(23,000,000)
Total long-term debt		5,253,000,000	5,183,000,000
CMS Energy [Member]
Debt Instrument [Line Items]
Total long-term debt		$ 2,678,000,000	2,605,000,000
Senior Notes 6.550% Due 2017 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		6.55%
Senior Notes 5.050% Due 2022 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		5.05%
Senior Notes 3.000% Due May 2026 [Member]
Debt Instrument [Line Items]
Interest rate		3.00%
Maturity Date		2,026
Principal amounts outstanding		$ 300,000,000
Senior Notes 3.000% Due May 2026 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		3.00%
Senior Notes 2.950% Due 2027 [Member]
Debt Instrument [Line Items]
Interest rate		2.95%
Maturity Date		2,027
Principal amounts outstanding		$ 275,000,000
Senior Notes 2.950% Due 2027 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		2.95%
Term Loan Facility Due 2017 [Member]
Debt Instrument [Line Items]
Maturity Date		2,018
Principal amounts outstanding		$ 180,000,000	180,000,000
Term Loan Facility Due 2017 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Three-month LIBOR plus a spread		0.85%
Interest rate at period end		1.61%
FMB's 5.500% Due 2016 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate		5.50%
FMB's 3.250% Due 2046 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.25%
Maturity Date	[1]	2,046
Principal amounts outstanding	[1]	$ 450,000,000
Tax-Exempt Pollution Control Revenue Bonds [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Maturity Date		2018-2035
Principal amounts outstanding		$ 103,000,000	103,000,000
Senior Notes [Member]
Debt Instrument [Line Items]
Principal amounts outstanding		$ 2,525,000,000	2,450,000,000
Senior Notes [Member] | Senior Notes 6.550% Due 2017 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		6.55%
Maturity Date		2,017
Principal amounts outstanding			250,000,000
Senior Notes [Member] | Senior Notes 5.050% Due 2018 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		5.05%
Maturity Date		2,018
Principal amounts outstanding			250,000,000
Senior Notes [Member] | Senior Notes 8.750% Due 2019 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		8.75%
Maturity Date		2,019
Principal amounts outstanding		$ 300,000,000	300,000,000
Senior Notes [Member] | Senior Notes 6.250% Due 2020 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		6.25%
Maturity Date		2,020
Principal amounts outstanding		$ 300,000,000	300,000,000
Senior Notes [Member] | Senior Notes 5.050% Due 2022 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		5.05%
Maturity Date		2,022
Principal amounts outstanding		$ 300,000,000	300,000,000
Senior Notes [Member] | Senior Notes 3.875% Due June 2024 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		3.875%
Maturity Date		2,024
Principal amounts outstanding		$ 250,000,000	250,000,000
Senior Notes [Member] | Senior Notes 3.000% Due May 2026 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		3.60%
Maturity Date		2,025
Principal amounts outstanding		$ 250,000,000	250,000,000
Senior Notes [Member] | Senior Notes 4.700% Due 2043 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		4.70%
Maturity Date		2,043
Principal amounts outstanding		$ 250,000,000	250,000,000
Senior Notes [Member] | Senior Notes 4.875% Due March 2044 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate	[2]	4.875%
Maturity Date		2,044
Principal amounts outstanding		$ 300,000,000	300,000,000
Senior Notes [Member] | Senior Notes 6.875% Due 2018 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate		6.875%
Maturity Date		2,018
Principal amounts outstanding		$ 180,000,000	180,000,000
Other CMS Subsidiaries [Member] | EnerBank Certificates Of Deposit [Member]
Debt Instrument [Line Items]
Interest rate	[3]	1.505%
Maturity Date		2017-2026
Interest-bearing Domestic Deposit, Brokered		$ 1,198,000,000	$ 1,098,000,000
Weighted-average interest rate		1.51%	1.36%
Certificate of deposit face value		$ 1,000
First Mortgage Bonds [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal amounts outstanding		$ 5,050,000,000	$ 4,773,000,000
Weighted-average Interest Rate (%)		4.57%	4.73%
First Mortgage Bonds [Member] | FMB's 5.500% Due August 2016 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	5.50%
Maturity Date	[1]	2,016
Principal amounts outstanding	[1]		$ 173,000,000
First Mortgage Bonds [Member] | FMB's 5.150% Due 2017 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	5.15%
Maturity Date	[1]	2,017
Principal amounts outstanding	[1]	$ 250,000,000	250,000,000
First Mortgage Bonds [Member] | FMB's 3.210% Due 2017 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.21%
Maturity Date	[1]	2,017
Principal amounts outstanding	[1]	$ 100,000,000	100,000,000
First Mortgage Bonds [Member] | FMB's 5.650% Due 2018 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	5.65%
Maturity Date	[1]	2,018
Principal amounts outstanding	[1]	$ 250,000,000	250,000,000
First Mortgage Bonds [Member] | FMB's 6.125% Due 2019 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	6.125%
Maturity Date	[1]	2,019
Principal amounts outstanding	[1]	$ 350,000,000	350,000,000
First Mortgage Bonds [Member] | FMB's 6.700% Due 2019 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	6.70%
Maturity Date	[1]	2,019
Principal amounts outstanding	[1]	$ 500,000,000	500,000,000
First Mortgage Bonds [Member] | FMB's 5.650% Due 2020 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	5.65%
Maturity Date	[1]	2,020
Principal amounts outstanding	[1]	$ 300,000,000	300,000,000
First Mortgage Bonds [Member] | FMB's 3.770% Due 2020 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.77%
Maturity Date	[1]	2,020
Principal amounts outstanding	[1]	$ 100,000,000	100,000,000
First Mortgage Bonds [Member] | FMB's 5.300% Due 2022 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	5.30%
Maturity Date	[1]	2,022
Principal amounts outstanding	[1]	$ 250,000,000	250,000,000
First Mortgage Bonds [Member] | FMB's 2.850% Due 2022 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	2.85%
Maturity Date	[1]	2,022
Principal amounts outstanding	[1]	$ 375,000,000	375,000,000
First Mortgage Bonds [Member] | FMB's 3.375% Due 2023 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.375%
Maturity Date	[1]	2,023
Principal amounts outstanding	[1]	$ 325,000,000	325,000,000
First Mortgage Bonds [Member] | FMB's 3.190% Due 2024 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.19%
Maturity Date	[1]	2,024
Principal amounts outstanding	[1]	$ 52,000,000	52,000,000
First Mortgage Bonds [Member] | FMB's 3.125% Due August 2024 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.125%
Maturity Date	[1]	2,024
Principal amounts outstanding	[1]	$ 250,000,000	250,000,000
First Mortgage Bonds [Member] | FMB's 3.390% Due 2027 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.39%
Maturity Date	[1]	2,027
Principal amounts outstanding	[1]	$ 35,000,000	35,000,000
First Mortgage Bonds [Member] | FMB's 5.800% Due 2035 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	5.80%
Maturity Date	[1]	2,035
Principal amounts outstanding	[1]	$ 175,000,000	175,000,000
First Mortgage Bonds [Member] | FMB's 6.170% Due 2040 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	6.17%
Maturity Date	[1]	2,040
Principal amounts outstanding	[1]	$ 50,000,000	50,000,000
First Mortgage Bonds [Member] | FMB's 4.970% Due 2040 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	4.97%
Maturity Date	[1]	2,040
Principal amounts outstanding	[1]	$ 50,000,000	50,000,000
First Mortgage Bonds [Member] | FMB's 4.310% Due 2042 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	4.31%
Maturity Date	[1]	2,042
Principal amounts outstanding	[1]	$ 263,000,000	263,000,000
First Mortgage Bonds [Member] | FMB's 3.950% Due 2043 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	3.95%
Maturity Date	[1]	2,043
Principal amounts outstanding	[1]	$ 425,000,000	425,000,000
First Mortgage Bonds [Member] | FMB's 4.100% Due 2045 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	4.10%
Maturity Date	[1]	2,045
Principal amounts outstanding	[1]	$ 250,000,000	250,000,000
First Mortgage Bonds [Member] | FMB's 4.350% Due August 2064 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	4.35%
Maturity Date	[1]	2,064
Principal amounts outstanding	[1]	$ 250,000,000	$ 250,000,000
Securitization Bonds [Member] | Consumers Energy Company [Member] | Consumers 2014 Securitization Funding [Member]
Debt Instrument [Line Items]
Weighted-average Interest Rate (%)		2.79%	2.69%
Securitization Bonds [Member] | Securitization Bonds 2.689% Due 2020-2029 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[4]	2.79%
Maturity Date	[5]	2020-2029
Principal amounts outstanding		$ 328,000,000	$ 353,000,000
[1]	The weighted-average interest rate for Consumers' first mortgage bonds was 4.57 percent at December 31, 2016 and 4.73 percent at December 31, 2015.
[2]	Outstanding borrowings bear interest at an annual interest rate of LIBOR plus 0.85 percent (1.61 percent at December 31, 2016).
[3]	The weighted-average interest rate for EnerBank's certificates of deposit was 1.51 percent at December 31, 2016 and 1.36 percent at December 31, 2015. EnerBank's primary deposit product consists of brokered certificates of deposit with varying maturities and having a face value of $1,000.
[4]	The weighted-average interest rate for Consumers' securitization bonds issued through its subsidiary Consumers 2014 Securitization Funding was 2.79 percent at December 31, 2016 and 2.69 percent at December 31, 2015.Principal and interest payments are made semiannually.
[5]	Principal and interest payments are made semiannually.

Financings And Capitalization69

Financings And Capitalization (Major Long-Term Debt Transactions) (Details)	12 Months Ended
	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
Principal Balance	$ 1,025,000,000
Debt retirement, principal	673,000,000
CMS Energy [Member]
Debt Instrument [Line Items]
Principal Balance	575,000,000
Debt retirement, principal	500,000,000
Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance	450,000,000
Debt retirement, principal	$ 173,000,000
Senior Notes 3.000% Due May 2026 [Member]
Debt Instrument [Line Items]
Interest rate	3.00%
Senior Notes 3.000% Due May 2026 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Principal Balance	$ 300,000,000
Interest rate	3.00%
Debt issuance date	May 2016
Maturity date	May 2,026
Senior Notes 2.950% Due 2027 [Member]
Debt Instrument [Line Items]
Interest rate	2.95%
Senior Notes 2.950% Due 2027 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Principal Balance	$ 275,000,000
Interest rate	2.95%
Debt issuance date	November 2016
Maturity date	February 2,027
Senior Notes 6.550% Due 2017 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Debt retirement, principal	$ 250,000,000
Interest rate	6.55%
Debt retirement date	December 2016
Maturity date	July 2,017
Senior Notes 5.050% Due 2022 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Debt retirement, principal	$ 250,000,000
Interest rate	5.05%
Debt retirement date	December 2016
Maturity date	February 2,018
FMB's 3.250% Due 2046 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance	$ 450,000,000
Interest rate	3.25%	[1]
Debt issuance date	August 2016
Maturity date	August 2,046
FMB's 5.500% Due 2016 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Debt retirement, principal	$ 173,000,000
Interest rate	5.50%
Debt retirement date	August 2016
Maturity date	August 2,016
[1]	The weighted-average interest rate for Consumers' first mortgage bonds was 4.57 percent at December 31, 2016 and 4.73 percent at December 31, 2015.

Financings and Capitalization70

Financings and Capitalization (Debt Maturities) (Details) $ in Millions	Dec. 31, 2016USD ($)
Long-term debt maturities, 2017	$ 864
Long-term debt maturities, 2018	975
Long-term debt maturities, 2019	1,326
Long-term debt maturities, 2020	850
Long-term debt maturities, 2021	103
Consumers Energy Company [Member]
Long-term debt maturities, 2017	375
Long-term debt maturities, 2018	523
Long-term debt maturities, 2019	876
Long-term debt maturities, 2020	426
Long-term debt maturities, 2021	$ 27

Financings And Capitalization71

Financings And Capitalization (Revolving Credit Facilities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Revolving Credit Facilities May 27, 2021 [Member]
Line of Credit Facility [Line Items]
Expiration Date	May 27, 2021	[1],[2]
Amount of Facility	$ 550	[1],[2]
Amount Borrowed		[1],[2]
Letters of Credit Outstanding	1	[1],[2]
Amount Available	549	[1],[2]
Revolving Credit Facilities May 27, 2021 [Member] | CMS Energy [Member]
Line of Credit Facility [Line Items]
Average borrowings	$ 3
Weighted average interest rate	1.68%
Revolving Credit Facilities May 27, 2021 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	May 27, 2021	[2],[3]
Amount of Facility	$ 650	[2],[3]
Amount Borrowed		[2],[3]
Letters of Credit Outstanding	7	[2],[3]
Amount Available	$ 643	[2],[3]
Revolving Credit Facilities November 23, 2017 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	Nov. 23, 2018	[3],[4]
Amount of Facility	$ 250	[3],[4]
Amount Borrowed		[3],[4]
Amount Available	$ 250	[3],[4]
Revolving Credit Facilities May 9, 2018 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	May 9, 2018	[3]
Amount of Facility	$ 30	[3]
Amount Borrowed		[3]
Letters of Credit Outstanding	$ 30	[3]
[1]	During the year ended December 31, 2016, CMS Energy's average borrowings totaled $3 million with a weighted-average interest rate of 1.68 percent. Obligations under this facility are secured by Consumers common stock.
[2]	In May 2016, the expiration date of this revolving credit agreement was extended from 2020 to 2021.
[3]	Obligations under this facility are secured by first mortgage bonds of Consumers.
[4]	In November 2016, the expiration date of this revolving credit agreement was extended from 2017 to 2018.

Financings And Capitalization72

Financings And Capitalization (Issuance Of Common Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended		24 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016
Financings And Capitalization [Abstract]
Number of Shares Issued	1,449,171	888,610	2,337,781
Average Price Per Share	$ 41.40	$ 33.76	$ 38.50
Proceeds	$ 60	$ 30	$ 90

Financings and Capitalization73

Financings and Capitalization (Preferred Stock of Subsidiary) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Par value of Preferred Stock	$ 0.01
Shares of Preferred Stock authorized	10,000,000
Consumers Energy Company [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Preferred stock Value	$ 37	$ 37
Preferred Stock $4.50 Series [Member] | Consumers Energy Company [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Par value of Preferred Stock	$ 100	$ 100
Shares of Preferred Stock authorized	7,500,000	7,500,000
Optional Redemption Price	$ 110	$ 110
Number of Shares	373,148	373,148
Preferred stock Value	$ 37	$ 37

Fair Value Measurements (Assets

Fair Value Measurements (Assets And Liabilties Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	$ 44	$ 158
Restricted cash equivalents	[1]	19	19
Nonqualified deferred compensation plan assets	[1]	12	10
Commodity contracts	[1]	1	1
Total	[1]	220	336
Nonqualified deferred compensation plan liabilities	[1]	12	10
Total	[1]	12	10
Consumers Energy Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash equivalents	[1]	19	19
Nonqualified deferred compensation plan assets	[1]	8	7
Commodity contracts	[1]	1	1
Total	[1]	165	162
Nonqualified deferred compensation plan liabilities	[1]	8	7
Total	[1]	8	7
DB SERP [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	3	2
DB SERP [Member] | Cash Equivalents [Member] | Consumers Energy Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	2	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]	141	146
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]	102	104
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]	$ 33	$ 29
[1]	All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3.

Fair Value Measurements (Asse75

Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Level 3 Inputs) (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance at beginning of period		$ 1	$ 1	$ 4
Total gains (losses) included in earnings	[1]	1	(1)
Total gains (losses) offset through regulatory accounting		(2)	2	(15)
Purchases		2	1	(1)
Settlements		(1)	(2)	13
Balance at end of period		1	1	1
Consumers Energy Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance at beginning of period		1	1	4
Total gains (losses) included in earnings	[1]	1
Total gains (losses) offset through regulatory accounting		(2)	2	(15)
Purchases		2		(1)
Settlements		(1)	(2)	13
Balance at end of period		$ 1	$ 1	$ 1
[1]	CMS Energy and Consumers record realized gains and losses for Level 3 recurring fair value measurements in earnings as a component of maintenance and other operating expenses or purchased and interchange power on their consolidated statements of income.

Financial Instruments (Narrativ

Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financial Instruments [Line Items]
Portion of long-term debt supported by third-party credit enhancements	$ 103	$ 103
Reclassified losses, net of tax	2	5	$ 3
Consumers Energy Company [Member]
Financial Instruments [Line Items]
Portion of long-term debt supported by third-party credit enhancements	103	103
Gain on CMS Energy common stock		9
Reclassified losses, net of tax	1	4	$ 2
Mutual Fund [Member] | DB SERP [Member]
Financial Instruments [Line Items]
Reclassified losses, before tax	5
Reclassified losses, net of tax	3
Available for sale - Cost	141	152
Mutual Fund [Member] | DB SERP [Member] | Consumers Energy Company [Member]
Financial Instruments [Line Items]
Reclassified losses, before tax	4
Reclassified losses, net of tax	2
Available for sale - Cost	102	108
CMS Energy Common Stock [Member] | Consumers Energy Company [Member]
Financial Instruments [Line Items]
Available for sale - Cost	$ 4	$ 4

Financial Instruments (Schedule

Financial Instruments (Schedule Of Carrying Amounts And Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity - Fair Value		$ 13	$ 11
Accounts receivable, current		12
Notes and accrued interest receivable		180	128
Other liabilities current		199	142
Current portion of long-term debt		864	684
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]
Notes payable, Fair Value	[1]	17	14
Long-term receivable, fair Value	[2]	22
Securities held to maturity - Fair Value		13	11
Long-term debt, Fair Value	[3]	9,504	9,084
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable, Fair Value	[1]	17	14
Long-term receivable, fair Value	[2]	22
Securities held to maturity - Fair Value		13	11
Long-term debt, Fair Value	[3]	9,953	9,599
Consumers Energy Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and accrued interest receivable		29
Other liabilities current		164	109
Current portion of long-term debt		375	198
Consumers Energy Company [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[2]	22
Notes receivable, Fair Value	[4]	45
Long-term debt, Fair Value	[5]	5,628	5,381
Consumers Energy Company [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term receivable, fair Value	[2]	22
Notes receivable, Fair Value	[4]	45
Long-term debt, Fair Value	[5]	5,903	5,684
EnerBank [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and accrued interest receivable		219	144
EnerBank [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, Fair Value	[3],[6]	1,326	1,161
EnerBank [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, Fair Value	[3],[6]	1,415	1,228
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		13	11
Long-term debt, Fair Value	[3]	8,990	8,648
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	[5]	4,940	4,733
Fair Value, Inputs, Level 3 [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable, Fair Value	[1]	17	14
Long-term receivable, fair Value	[2]	22
Long-term debt, Fair Value	[3]	963	951
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	[2]	22
Notes receivable, Fair Value	[4]	45
Long-term debt, Fair Value	[5]	963	951
Fair Value, Inputs, Level 3 [Member] | EnerBank [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, Fair Value	[3],[6]	$ 1,415	$ 1,228
[1]	Includes current portion of long-term payables of $1 million at December 31, 2016 and 2015.
[2]	Includes current accounts receivable of $12 million at December 31, 2016.
[3]	Includes current portion of long-term debt of $864 million at December 31, 2016 and $684 million at December 31, 2015.
[4]	Includes current portion of notes receivable of $29 million at December 31, 2016.
[5]	Includes current portion of long-term debt of $375 million at December 31, 2016 and $198 million at December 31, 2015.
[6]	Includes current portion of notes receivable of $219 million at December 31, 2016 and $144 million at December 31, 2015.

Financial Instruments (Schedu78

Financial Instruments (Schedule Of Investment Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Investment Securities [Line Items]
Held to maturity securities - Cost	$ 13	$ 11
Held to maturity securities - Fair Value	13	11
CMS Energy Common Stock [Member] | Consumers Energy Company [Member]
Investment Securities [Line Items]
Available for sale - Cost	4	4
Available for sale - Unrealized Gains	29	25
Available for sale - Fair Value	33	29
DB SERP [Member] | Mutual Fund [Member]
Investment Securities [Line Items]
Available for sale - Cost	141	152
Available for sale - Unrealized Losses		6
Available for sale - Fair Value	141	146
DB SERP [Member] | Mutual Fund [Member] | Consumers Energy Company [Member]
Investment Securities [Line Items]
Available for sale - Cost	102	108
Available for sale - Unrealized Losses		4
Available for sale - Fair Value	$ 102	$ 104

Financial Instruments (Summary

Financial Instruments (Summary Of Sales Activity For Investment Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Proceeds from Sales of Available-for-Sale Securities	$ 6	$ 3	$ 8
Consumers Energy Company [Member]
Proceeds from Sales of Available-for-Sale Securities	$ 4	$ 2	$ 6

Notes Receivable (Narrative) (D

Notes Receivable (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
EnerBank notes receivable held for sale	$ 39	$ 16
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned income	84	82
Delinquent loans	11	8
Loans modified as troubled debt restructurings	1	1
Receivables Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned income	$ 8	$ 3

Notes Receivable (Schedule Of C

Notes Receivable (Schedule Of Current And Non-Current Notes Receivable) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 180	$ 128
EnerBank notes receivable held for sale	39	16
Total notes receivable	1,326	1,161
Consumers Energy Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	29
Total notes receivable	45
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	219	144
Noncurrent notes receivable	1,088	1,017
Receivables, Net Of Allowance For Loan Losses [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	151	128
Receivables Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	39	$ 16
State Of Michigan Tax Settlement [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	29
Noncurrent notes receivable	19
State Of Michigan Tax Settlement [Member] | Consumers Energy Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	29
Noncurrent notes receivable	$ 16

Notes Receivable (Schedule Of A

Notes Receivable (Schedule Of Allowance For Loan Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Notes Receivable [Abstract]
Allowance for loan losses, at beginning of period	$ 9	$ 8
Charge-offs	(14)	(8)
Recoveries	2	1
Provision for loan losses	19	8
Allowance for loan losses, at end of period	$ 16	$ 9

Plant, Property, and Equipmen83

Plant, Property, and Equipment (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)MW	Dec. 31, 2014USD ($)
Property, Plant and Equipment [Line Items]
Change in net plant, property, and equipment	$ 34,000,000
Payments to acquire plant	1,672,000,000	$ 1,564,000,000	$ 1,577,000,000
Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Payments to acquire plant	$ 1,656,000,000	$ 1,537,000,000	$ 1,573,000,000
Gas Fueled Electric Generating Units [Member] | Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Plant capacity | MW		540
Payments to acquire plant		$ 155,000,000
Goodwill		$ 0

Plant, Property, and Equipmen84

Plant, Property, and Equipment (Schedule Of Plant, Property, and Equipment) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross		$ 21,010	$ 18,943	$ 17,721
Construction work in progress		761	1,509
Less accumulated depreciation and amortization		(6,056)	(5,747)
Total plant, property, and equipment	[1]	15,715	14,705
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross		20,838	18,797	$ 17,580
Construction work in progress		759	1,467
Less accumulated depreciation and amortization		(5,994)	(5,676)
Total plant, property, and equipment	[1]	15,603	14,588
Public Utilities, Property Plant and Equipment Additions		2,300	1,400
Public Utilities, Property Plant and Equipment Disposals		$ 285	187
Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Consumers		5 years
Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Consumers		125 years
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing		$ 5,900	4,925
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Generation		22 years
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Generation		125 years
Electric Distribution [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution		$ 7,149	6,809
Electric Distribution [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		20 years
Electric Distribution [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		75 years
Electric Transmission [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Transmission		$ 59
Electric Transmission [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		46 years
Electric Transmission [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		75 years
Electric Other [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 1,137	1,039
Electric Other [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		5 years
Electric Other [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		50 years
Electric Capital Leases [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation	[1]	$ 295	286
Gas Distribution [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution		$ 3,806	3,497
Gas Distribution [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		28 years
Gas Distribution [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		80 years
Gas Transmission [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Transmission		$ 1,124	981
Gas Transmission [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		17 years
Gas Transmission [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		75 years
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	[2]	$ 630	601
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other	[2]	29 years
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other	[2]	65 years
Gas Other [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 708	630
Gas Other [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		5 years
Gas Other [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		50 years
Gas Capital Leases [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation		$ 15	14
Natural Gas [Member] | Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		26	26
Enterprises IPP [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross		$ 141	95
Enterprises IPP [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		3 years
Enterprises IPP [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		30 years
Enterprises Other [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Plant, property, and equipment, gross		$ 16	25
Enterprises Other [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		3 years
Enterprises Other [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		40 years
Other [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Other non-utility property		$ 15	26
Other [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		1 year
Other [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		7 years
Other [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Other non-utility property		$ 15	$ 15
Other [Member] | Consumers Energy Company [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		8 years
Other [Member] | Consumers Energy Company [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		51 years
[1]	For the year ended December 31, 2016, Consumers' plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 2015, Consumers' plant additions were $1.4 billion and plant retirements were $187 million.
[2]	Underground storage includes base natural gas of $26 million at December 31, 2016 and 2015. Base natural gas is not subject to depreciation.

Plant, Property, and Equipmen85

Plant, Property, and Equipment (Public Utilities, Allowance for Funds Used During Construction, Schedule of Composite Rate Table) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consumers Energy Company [Member]
AFUDC capitalization rate	7.00%	7.10%	7.20%

Plant, Property, and Equipmen86

Plant, Property, and Equipment (Schedule of Capital Leased Asssets) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Capital Leased Assets, Gross, Additions	[1]	$ 1,633	$ 1,741	$ 1,616
Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Capital Leased Assets, Gross, Additions	[1]	1,618	1,694	1,612
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation		172	152
Consumers Energy Company [Member] | Assets Held under Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Balance at beginning of period		300	295
Capital Leased Assets, Gross, Additions		13	17
Capital Leased Assets, Gross, Net retirements and other adjustments		(3)	(12)
Balance at end of period		$ 310	$ 300	$ 295
[1]	Amounts include purchase of capital lease additions. Amounts also include a portion of Consumers' capital expenditures for plant and equipment attributable to both the electric and gas utility businesses.

Plant, Property, and Equipmen87

Plant, Property, and Equipment (Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated Depreciation, Depletion and Amortization	$ 6,056	$ 5,747
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	5,994	5,676
Utility Plant Assets [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated Depreciation, Depletion and Amortization	5,993	5,674
Utility Plant Assets [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	5,993	5,674
Non-Utility Plant Assets [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated Depreciation, Depletion and Amortization	63	73
Non-Utility Plant Assets [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ 1	$ 2

Plant, Property, and Equipmen88

Plant, Property, and Equipment (Public Utilities Property Plant and Equipment Schedule of Composite Depreciation Rate Table) (Details) - Consumers Energy Company [Member]	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Electric Utility Property [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.90%	3.50%	3.50%
Gas Utility Property [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	2.90%	2.80%	2.80%
Other property [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	9.80%	8.70%	7.70%

Plant, Property, and Equipmen89

Plant, Property, and Equipment (Schedule Of Depreciation And Amortization Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Depreciation expense - plant, property, and equipment	$ 687	$ 591	$ 551
Total depreciation and amortization expense	811	750	685
Securitized Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	25	83	75
Other Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense		2	5
Software [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	96	70	50
Other Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	3	4	4
Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense - plant, property, and equipment	680	586	546
Total depreciation and amortization expense	803	744	678
Consumers Energy Company [Member] | Securitized Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	25	83	75
Consumers Energy Company [Member] | Other Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense		2	5
Consumers Energy Company [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	95	69	49
Consumers Energy Company [Member] | Other Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	$ 3	$ 4	$ 3

Plant, Property, and Equipmen90

Plant, Property, and Equipment (Schedule Of Estimated Amortization Expense For Intangibles) (Details) $ in Millions	Dec. 31, 2016USD ($)
2,017	$ 115
2,018	120
2,019	112
2,020	95
2,021	77
Consumers Energy Company [Member]
2,017	114
2,018	119
2,019	111
2,020	94
2,021	$ 77

Plant, Property, and Equipmen91

Plant, Property, and Equipment (Schedule of Finite-Lived Intangible Assets by Major Class Table) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	$ 1,052	$ 930
Finite-Lived Intangible Assets, Accumulated Amortization		444	368
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	1,043	925
Finite-Lived Intangible Assets, Accumulated Amortization		440	365
Public Utilities, Property Plant and Equipment Additions		2,300	1,400
Public Utilities, Property Plant and Equipment Disposals		285	187
Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	853	734
Finite-Lived Intangible Assets, Accumulated Amortization		367	294
Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	845	729
Finite-Lived Intangible Assets, Accumulated Amortization		363	291
Leasehold Improvements [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1],[2]	7	7
Finite-Lived Intangible Assets, Accumulated Amortization	[2]	6	5
Leasehold Improvements [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1],[2]	7	7
Finite-Lived Intangible Assets, Accumulated Amortization	[2]	6	5
Intangible Plant [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property Plant and Equipment Additions		141	140
Public Utilities, Property Plant and Equipment Disposals		23
Rights of Way [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	155	153
Finite-Lived Intangible Assets, Accumulated Amortization		48	46
Rights of Way [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	155	153
Finite-Lived Intangible Assets, Accumulated Amortization		48	46
Franchises and Consents [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	15	15
Finite-Lived Intangible Assets, Accumulated Amortization		8	8
Franchises and Consents [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	15	15
Finite-Lived Intangible Assets, Accumulated Amortization		8	8
Other Intangible Assets [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	22	21
Finite-Lived Intangible Assets, Accumulated Amortization		15	15
Other Intangible Assets [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	21	21
Finite-Lived Intangible Assets, Accumulated Amortization		$ 15	$ 15
Minimum [Member] | Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		1 year
Minimum [Member] | Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		3 years
Minimum [Member] | Rights of Way [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		50 years
Minimum [Member] | Rights of Way [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		50 years
Minimum [Member] | Franchises and Consents [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		5 years
Minimum [Member] | Franchises and Consents [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		5 years
Maximum [Member] | Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		15 years
Maximum [Member] | Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		15 years
Maximum [Member] | Rights of Way [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		75 years
Maximum [Member] | Rights of Way [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		75 years
Maximum [Member] | Franchises and Consents [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		30 years
Maximum [Member] | Franchises and Consents [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		30 years
[1]	For the year ended December 31, 2016, Consumers' intangible asset additions were $141 million and intangible asset retirements were $23 million. For the year ended December 31, 2015, Consumers' intangible asset additions were $140 million and there were no retirements.
[2]	Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended.

Plant, Property, and Equipmen92

Plant, Property, and Equipment (Jointly Owned Regulated Utility Facilities) (Details) $ in Millions	Dec. 31, 2016USD ($)
J.H. Campbell Unit 3 [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Ownership share	93.30%
Utility plant in service	$ 1,648
Accumulated depreciation	(529)
Construction work-in-progress	13
Net investment	$ 1,132
Ludington [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Ownership share	51.00%
Utility plant in service	$ 291
Accumulated depreciation	(150)
Construction work-in-progress	157
Net investment	298
Distribution [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant in service	206
Accumulated depreciation	(63)
Construction work-in-progress	7
Net investment	$ 150

Leases And Palisades Financin93

Leases And Palisades Financing (Narrative) (Details) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2016USD ($)	Dec. 31, 2016USD ($)MW	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Consumers Energy Company [Member]
Leases [Line Items]
Finance Lease Term		15 years
Coal-Carrying Railcars [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Operating leases without extension provisions, remaining term		7 years
Operating leases with extension provisions, remaining term		10 years
Gas Transportation Pipeline into Karn [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Capital Lease Term		15 years
Capital Lease Remaining Term		5 years
Gas Transportation Pipeline into Zeeland [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Capital Lease Term		5 years
Capital lease renewal term		5 years
Capital Lease Remaining Term		1 year
Minimum [Member] | Coal-Carrying Railcars [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Operating leases, term		1 year
Minimum [Member] | Long-term PPAs [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Lease term		1 year
Maximum [Member] | Coal-Carrying Railcars [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Operating leases, term		15 years
Maximum [Member] | Vehicle Fleet Operations [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Capital Lease Term		120 months
Maximum [Member] | Long-term PPAs [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Lease term		16 years
Financing Leases [Member]
Leases [Line Items]
Finance Leases Lessee Balance Sheet Assets Amortization And Interest Charges | $	$ 17	$ 17	$ 18	$ 19
Financing Leases [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Lease termination cost | $	$ 172
Palisades PPA [Member]
Leases [Line Items]
Unrecorded Unconditional Purchase Obligations, Maximum Quantity | MW		798
Palisades PPA [Member] | Consumers Energy Company [Member]
Leases [Line Items]
Unrecorded Unconditional Purchase Obligations, Maximum Quantity | MW		798

Leases And Palisades Financin94

Leases And Palisades Financing (Schedule of Rent Expense) (Details) - Consumers Energy Company [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Leases [Line Items]
Contingent rental expense	[1]	$ 82	$ 82	$ 85
PPAs [Member]
Leases [Line Items]
Minimum operating lease expense		6	6	6
Non-PPAs [Member]
Leases [Line Items]
Minimum operating lease expense		$ 14	$ 19	$ 19
[1]	Contingent rental expense is related to capital and operating lease PPAs and is based on delivery of energy and capacity in excess of minimum lease payments.

Leases And Palisades Financin95

Leases And Palisades Financing (Schedule of Future Minimum Lease Payments for Leases) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Leases [Line Items]
Capital and Financing Leases, Non-current portion	$ 110	$ 118
Consumers Energy Company [Member]
Leases [Line Items]
Capital and Financing Leases, Non-current portion	110	$ 118
Operating Leases, 2017	20
Operating Leases, 2018	16
Operating Leases, 2019	10
Operating Leases, 2020	10
Operating Leases, 2021	10
Operating Leases, 2022 and thereafter	15
Operating Leases, Total minimum lease payments	81
Consumers Energy Company [Member] | Capital Leases [Member]
Leases [Line Items]
Capital and Financing Leases, 2017	15
Capital and Financing Leases, 2018	14
Capital and Financing Leases, 2019	14
Capital and Financing Leases, 2020	12
Capital and Financing Leases, 2021	11
Capital and Financing Leases, 2022 and thereafter	25
Capital and Financing Leases, Total minimum lease payments	91
Capital and Financing Leases, Less imputed interest	28
Capital and Financing Leases, Present value of net minimum lease payments	63
Capital and Financing Leases, Less current portion	9
Capital and Financing Leases, Non-current portion	54
Consumers Energy Company [Member] | Financing Leases [Member]
Leases [Line Items]
Capital and Financing Leases, 2017	17
Capital and Financing Leases, 2018	16
Capital and Financing Leases, 2019	15
Capital and Financing Leases, 2020	14
Capital and Financing Leases, 2021	14
Capital and Financing Leases, 2022 and thereafter	3
Capital and Financing Leases, Total minimum lease payments	79
Capital and Financing Leases, Less imputed interest	10
Capital and Financing Leases, Present value of net minimum lease payments	69
Capital and Financing Leases, Less current portion	13
Capital and Financing Leases, Non-current portion	$ 56

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	$ 439	$ 340
Incurred	3	11
Settled	(18)	(6)
Accretion	23	20
Cash flow Revisions		74
ARO Liability, end of period	447	439
Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	438	339
Incurred	3	11
Settled	(18)	(6)
Accretion	23	20
Cash flow Revisions		74
ARO Liability, end of period	446	438
Gas Treating Plant and Gas Wells [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	1	1
Incurred
Settled
Accretion
Cash flow Revisions
ARO Liability, end of period	1	1
Coal Ash Disposal Areas [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	200	120
Settled	(8)
Accretion	9	6
Cash flow Revisions		74
ARO Liability, end of period	201	200
Gas Distribution Cut, Purge, Cap [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	178	162
Incurred	2	11
Settled	(9)	(6)
Accretion	11	11
ARO Liability, end of period	182	178
Asbestos Abatement [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	54	51
Settled	(1)
Accretion	3	3
ARO Liability, end of period	56	54
Renewable Generation Assets [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	6	6
Incurred	1
Settled
Accretion
Cash flow Revisions
ARO Liability, end of period	$ 7	$ 6

Retirement Benefits (Narrative)

Retirement Benefits (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)item	Dec. 31, 2014USD ($)item
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 108	$ 262	$ 32
Union employees percentage	39.00%
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 98	243	29
Union employees percentage	41.00%
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	$ 2,101	$ 2,013	$ 1,979
Estimated time of amortization of gains losses	10 years	10 years	10 years
Period for gains or losses to be included in market related value	5 years
Postretirement benefits contributions	$ 100	$ 225
DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated time of amortization of gains losses	10 years	10 years	10 years
Period for gains or losses to be included in market related value	5 years
Postretirement benefits contributions	$ 93	$ 209
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	$ 1,264	$ 1,208	$ 1,265
Retirement age requirement | item	55	55	55
Retirement years of service	10 years
Retirement years of service with disability	15 years
Ultimate health care cost trend rate	4.75%
Year that rate reaches ultimate trend rate	2,027
Estimated time of amortization of gains losses	11 years	13 years	13 years
Estimated time of prior service cost		10 years
Postretirement benefits contributions		$ 29	$ 25
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	$ 1,184	$ 1,133	$ 1,186
Retirement age requirement | item	55	55	55
Retirement years of service	10 years
Retirement years of service with disability	15 years
Ultimate health care cost trend rate	4.75%
Year that rate reaches ultimate trend rate	2,027
Estimated time of amortization of gains losses	11 years	13 years	13 years
Estimated time of prior service cost		10 years
Postretirement benefits contributions		$ 29	$ 25
Pension And OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortized net gains and losses in excess of PBO or MRV	10.00%	10.00%	10.00%
Pension And OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortized net gains and losses in excess of PBO or MRV	10.00%	10.00%	10.00%
Defined Company Contribution Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan cost, defined contribution plan	$ 20	$ 16	$ 13
Defined Company Contribution Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan cost, defined contribution plan	$ 19	16	13
DC SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum years of participation before vesting	5 years
Trust assets	$ 3	2
DC SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum years of participation before vesting	5 years
Trust assets	$ 3	2
401 (K) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan cost, defined contribution plan	$ 24	19	18
Employer match of eligible contributions	100.00%
Employer match of eligible wages	3.00%
Secondary employer match of eligible contributions	50.00%
Secondary employer match of eligible wages	2.00%
401 (K) Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan cost, defined contribution plan	$ 23	19	18
Employer match of eligible contributions	100.00%
Employer match of eligible wages	3.00%
Secondary employer match of eligible contributions	50.00%
Secondary employer match of eligible wages	2.00%
Minimum [Member] | Defined Company Contribution Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer match of eligible wages	5.00%
Minimum [Member] | Defined Company Contribution Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer match of eligible wages	5.00%
Minimum [Member] | DC SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan contribution percentage	5.00%
Minimum [Member] | DC SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan contribution percentage	5.00%
Maximum [Member] | Defined Company Contribution Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer match of eligible wages	7.00%
Maximum [Member] | Defined Company Contribution Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer match of eligible wages	7.00%
Maximum [Member] | DC SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan cost, defined contribution plan	$ 1	1	1
Plan contribution percentage	15.00%
Maximum [Member] | DC SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan cost, defined contribution plan	$ 1	$ 1	$ 1
Plan contribution percentage	15.00%
Under Age 65 [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year	7.00%	7.25%
Under Age 65 [Member] | OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year	7.00%	7.25%
Over Age 65 [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year	7.75%	8.00%
Over Age 65 [Member] | OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year	7.75%	8.00%

Retirement Benefits (Schedule O

Retirement Benefits (Schedule Of SERP Trust Assets, ABO And Contributions) (Details) - DB SERP [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
ABO	$ 140	$ 143
Contributions	25
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
ABO	97	101
Contributions	17
DB SERP Trust Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	148	144
DB SERP Trust Assets [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	$ 106	$ 104

Retirement Benefits (Schedule99

Retirement Benefits (Schedule Of Effect Of One-Percentage-Point Change In Assumed Health Care Cost Trend Rates) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components	$ 13
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	201
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components	(10)
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	(163)
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components	13
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	196
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components	(10)
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	$ (159)

Retirement Benefits (Schedul100

Retirement Benefits (Schedule Of Assumptions Used) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual rate of return on plan assets		8.00%	(2.00%)	7.40%
DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	[1],[2],[3]	4.30%	4.52%	4.10%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	[3]	3.60%	3.00%	3.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	[3],[4]	7.25%	7.50%	7.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Service Cost Discount Rate	[1],[2],[3]	4.79%	4.10%	4.90%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Interest Cost Discount Rate	[3]	3.66%	4.10%	4.90%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	[3]	3.00%	3.00%	3.00%
Actual rate of return on plan assets		8.00%	(2.00%)	7.40%
DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	[1],[2],[3]	4.16%	4.43%	4.10%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	[3]	5.50%	5.50%	5.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Service Cost Discount Rate	[1],[2],[3]	4.87%	4.10%	4.90%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Interest Cost Discount Rate	[3]	3.64%	4.10%	4.90%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	[3]	5.50%	5.50%	5.50%
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	[1],[2],[3]	4.49%	4.70%	4.30%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	[3],[4]	7.25%	7.25%	7.25%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Service Cost Discount Rate	[1],[2],[3]	4.75%	4.30%	5.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Interest Cost Discount Rate	[3]	3.89%	4.30%	5.10%
Change in Assumptions for Pension Plans [Member] | DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in service cost and interest cost		$ 23
Change in Assumptions for Pension Plans [Member] | DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in service cost and interest cost		22
Change in Assumptions for Pension Plans [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in service cost and interest cost		12
Change in Assumptions for Pension Plans [Member] | OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Reduction in service cost and interest cost		$ 11
[1]	In January 2016, CMS Energy and Consumers changed the method they use to determine the discount rate used to calculate the service cost and interest cost components of net periodic benefit costs for the DB Pension and OPEB Plans. Historically, the discount rate used for this purpose represented a single weighted-average rate derived from the yield curve used to determine the benefit obligation. CMS Energy and Consumers have elected to use instead a full-yield-curve approach in the estimation of service cost and interest cost; this approach is more accurate in that it applies individual spot rates along the yield curve to future projected benefit payments based on the time of payment. This change represented a change in accounting estimate and did not impact years prior to 2016. As a result of changing to the full-yield-curve approach to determine the discount rate, for the year ended December 31, 2016, the service cost and interest cost components of net periodic benefit costs were reduced by $23 million for the DB Pension Plan and $12 million for the OPEB Plan for CMS Energy and by $22 million for the DB Pension Plan and $11 million for the OPEB Plan for Consumers.
[2]	The discount rate reflects the rate at which benefits could be effectively settled and is equal to the equivalent single rate resulting from a yield-curve analysis. This analysis incorporated the projected benefit payments specific to CMS Energy's and Consumers' DB Pension Plan and OPEB Plan and the yields on high-quality corporate bonds rated Aa or better.
[3]	The mortality assumption for benefit obligations was based on the RP-2014 mortality table, with projection scales MP-2016 for 2016, MP-2015 for 2015, and MP-2014 for 2014. The mortality assumption for net periodic benefit cost for 2016 and 2015 was based on the RP-2014 mortality table, with projection scales MP-2015 for 2016 and MP-2014 for 2015, and for 2014 was based on the RP-2000 mortality table.
[4]	CMS Energy and Consumers determined the long-term rate of return using historical market returns, the present and expected future economic environment, the capital market principles of risk and return, and the expert opinions of individuals and firms with financial market knowledge. CMS Energy and Consumers considered the asset allocation of the portfolio in forecasting the future expected total return of the portfolio. The goal was to determine a long-term rate of return that could be incorporated into the planning of future cash flow requirements in conjunction with the change in the liability. Annually, CMS Energy and Consumers review for reasonableness and appropriateness the forecasted returns for various classes of assets used to construct an expected return model. CMS Energy's and Consumers' expected long-term rate of return on DB Pension Plan assets was 7.25 percent in 2016. The actual return (loss) on DB Pension Plan assets was 8.0 percent in 2016, (2.0) percent in 2015, and 7.4 percent in 2014.

Retirement Benefits (Schedul101

Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension And DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 42	$ 50	$ 42
Interest cost	90	108	105
Expected return on plan assets	(147)	(138)	(135)
Amortization of Net loss	71	97	60
Amortization of Prior service cost (credit)	4	1	1
Net periodic cost (credit)	60	118	73
Pension And DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	41	49	41
Interest cost	87	103	100
Expected return on plan assets	(143)	(134)	(131)
Amortization of Net loss	68	93	59
Amortization of Prior service cost (credit)	4	1	1
Net periodic cost (credit)	57	112	70
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	42	49
Interest cost	85	102
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	18	25	20
Interest cost	46	58	56
Expected return on plan assets	(85)	(91)	(88)
Amortization of Net loss	21	21	2
Amortization of Prior service cost (credit)	(41)	(41)	(41)
Net periodic cost (credit)	(41)	(28)	(51)
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	17	25	20
Interest cost	45	56	54
Expected return on plan assets	(80)	(86)	(83)
Amortization of Net loss	22	22	3
Amortization of Prior service cost (credit)	(40)	(40)	(40)
Net periodic cost (credit)	$ (36)	$ (23)	$ (46)

Retirement Benefits (Schedul102

Retirement Benefits (Schedule Of Net Loss And Prior Service Cost (Credit) That Will Be Amortized In Next Fiscal Year) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset	$ 82
AOCI	2
DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset	82
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset	(2)
AOCI	(2)
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset	$ (2)

Retirement Benefits (Schedul103

Retirement Benefits (Schedule Of Benefit Obligations In Excess Of Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		$ 2,403	$ 2,547
Service cost		42	49
Interest cost		85	102
Plan amendments			13
Actuarial (gain) loss	[1]	196	(153)
Benefits paid		(164)	(155)
Benefit obligation at end of period		2,562	2,403	$ 2,547
Plan assets at fair value at beginning of period		2,013	1,979
Actual return on plan assets		152	(36)
Company contributions		100	225
Actual benefits paid		(164)	(155)
Plan assets at fair value at end of period		2,101	2,013	1,979
Funded status	[1],[2]	(461)	(390)
DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status		(441)	(368)
DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		150	156
Service cost			1
Interest cost		5	6
Actuarial (gain) loss		4	(5)
Benefits paid		(8)	(8)
Benefit obligation at end of period		151	150	156
Company contributions		8	8
Actual benefits paid		(8)	(8)
Funded status		(151)	(150)
DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		106	111
Service cost			1
Interest cost		4	4
Actuarial (gain) loss	[1]	4	(5)
Benefits paid		(5)	(5)
Benefit obligation at end of period		109	106	111
Company contributions		5	5
Actual benefits paid		(5)	(5)
Funded status		(109)	(106)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		1,227	1,378
Service cost		18	25	20
Interest cost		46	58	56
Plan amendments			(25)
Actuarial (gain) loss	[1]	171	(152)
Benefits paid		(54)	(57)
Benefit obligation at end of period		1,408	1,227	1,378
Plan assets at fair value at beginning of period		1,208	1,265
Actual return on plan assets		109	(29)
Company contributions			29
Actual benefits paid		(53)	(57)
Plan assets at fair value at end of period		1,264	1,208	1,265
Funded status		(144)	(19)
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		1,188	1,336
Service cost		17	25	20
Interest cost		45	56	54
Plan amendments			(24)
Actuarial (gain) loss	[1]	167	(150)
Benefits paid		(52)	(55)
Benefit obligation at end of period		1,365	1,188	1,336
Plan assets at fair value at beginning of period		1,133	1,186
Actual return on plan assets		103	(27)
Company contributions			29
Actual benefits paid		(52)	(55)
Plan assets at fair value at end of period		1,184	1,133	$ 1,186
Funded status		$ (181)	$ (55)
[1]	The actuarial loss for 2016 was primarily the result of claims, experience, and lowering the discount rates used in calculating the plans' obligations. The actuarial gain for 2015 was primarily the result of increasing the discount rates used in calculating the plans' obligations.
[2]	At December 31, 2016, $441 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses. At December 31, 2015, $368 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses.

Retirement Benefits (Schedul104

Retirement Benefits (Schedule Of Retirement Benefit Plan Assets (Liabilities)) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	$ 789	$ 591
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	730	529
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	461	390
DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	441	368
DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	8	8
Non-current liabilities	143	142
DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	5	5
Non-current liabilities	104	101
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	144	19
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	$ 181	$ 55

Retirement Benefits (Schedul105

Retirement Benefits (Schedule Of Accumulated And Projected Benefit Obligations) (Details) - DB Pension Plan [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Pension PBO	$ 2,562	$ 2,403	$ 2,547
Pension ABO	2,250	2,140
Fair value of Pension Plan assets	$ 2,101	$ 2,013	$ 1,979

Retirement Benefits (Schedul106

Retirement Benefits (Schedule Of Net Periodic Benefit Cost Not yet Recognized) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Pension And DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets (liabilities), Net loss	$ 1,062	$ 944
Regulatory assets (liabilities), Prior service cost (credit)	15	19
Regulatory assets (liabilities)	1,077	963
AOCI, Net loss (gain)	93	86
AOCI, Prior service cost (credit)	1	1
Total amounts not yet recognized as component of net periodic benefit cost	1,171	1,050
Pension And DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets (liabilities), Net loss	1,062	944
Regulatory assets (liabilities), Prior service cost (credit)	15	19
Regulatory assets (liabilities)	1,077	963
AOCI, Net loss (gain)	33	29
Total amounts not yet recognized as component of net periodic benefit cost	1,110	992
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets (liabilities), Net loss	483	360
Regulatory assets (liabilities), Prior service cost (credit)	(187)	(227)
Regulatory assets (liabilities)	296	133
AOCI, Net loss (gain)	(8)	(11)
AOCI, Prior service cost (credit)	(6)	(8)
Total amounts not yet recognized as component of net periodic benefit cost	282	114
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets (liabilities), Net loss	483	360
Regulatory assets (liabilities), Prior service cost (credit)	(187)	(227)
Regulatory assets (liabilities)	296	133
Total amounts not yet recognized as component of net periodic benefit cost	$ 296	$ 133

Retirement Benefits (Schedul107

Retirement Benefits (Schedule Of Allocation Of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	$ 2,101	$ 2,013
DB Pension Plan [Member] | Cash and Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	110	215
DB Pension Plan [Member] | Cash and Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	110	215
DB Pension Plan [Member] | U.S. Government and Agencies Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1	19
DB Pension Plan [Member] | U.S. Government and Agencies Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1	19
DB Pension Plan [Member] | Corporate Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	266	243
DB Pension Plan [Member] | Corporate Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	266	243
DB Pension Plan [Member] | State and Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	9	8
DB Pension Plan [Member] | State and Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	9	8
DB Pension Plan [Member] | Foreign Corporate Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	25	16
DB Pension Plan [Member] | Foreign Corporate Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	25	16
DB Pension Plan [Member] | Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	571	538
DB Pension Plan [Member] | Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	571	538
DB Pension Plan [Member] | Plan Assets Excluding Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	982	1,039
DB Pension Plan [Member] | Plan Assets Excluding Pooled Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	681	753
DB Pension Plan [Member] | Plan Assets Excluding Pooled Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	301	286
DB Pension Plan [Member] | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1,119	974
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1,264	1,208
OPEB [Member] | Cash and Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	39	51
OPEB [Member] | Cash and Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	39	51
OPEB [Member] | U.S. Government and Agencies Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits		3
OPEB [Member] | U.S. Government and Agencies Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits		3
OPEB [Member] | Corporate Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	38	34
OPEB [Member] | Corporate Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	38	34
OPEB [Member] | State and Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1	1
OPEB [Member] | State and Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1	1
OPEB [Member] | Foreign Corporate Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	4	2
OPEB [Member] | Foreign Corporate Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	4	2
OPEB [Member] | Common Stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	44	54
OPEB [Member] | Common Stocks [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	44	54
OPEB [Member] | Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	563	456
OPEB [Member] | Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	563	456
OPEB [Member] | Plan Assets Excluding Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	689	601
OPEB [Member] | Plan Assets Excluding Pooled Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	646	561
OPEB [Member] | Plan Assets Excluding Pooled Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	43	40
OPEB [Member] | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	$ 575	$ 607

Retirement Benefits (Schedul108

Retirement Benefits (Schedule Of Pooled Funds Components) (Details)	Dec. 31, 2016	Dec. 31, 2015
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
U.S. equity securities	67.00%	62.00%
Foreign equity securities	16.00%	18.00%
U.S. fixed-income securities	9.00%	11.00%
Foreign fixed-income securities	4.00%	6.00%
Alternative investments	4.00%	3.00%
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
U.S. equity securities	72.00%	58.00%
Foreign equity securities	13.00%	13.00%
U.S. fixed-income securities	8.00%	22.00%
Foreign fixed-income securities	4.00%	5.00%
Alternative investments	3.00%	2.00%

Retirement Benefits (Schedul109

Retirement Benefits (Schedule Of Plan Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 108	$ 262	$ 32
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	98	243	29
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions		29	25
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions		29	$ 25
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	100	225
DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 93	$ 209
Equity Securities [Member] | Postretirement Health Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	50.00%
Equity Securities [Member] | Postretirement Life Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	42.00%
Equity Securities [Member] | DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	53.00%
Fixed Income Funds [Member] | Postretirement Health Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	30.00%
Fixed Income Funds [Member] | Postretirement Life Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	28.00%
Fixed Income Funds [Member] | DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	32.00%
Alternative Strategy Investments [Member] | Postretirement Health Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	20.00%
Alternative Strategy Investments [Member] | Postretirement Life Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	30.00%
Alternative Strategy Investments [Member] | DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	15.00%

Retirement Benefits (Schedul110

Retirement Benefits (Schedule Of Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2016USD ($)
DB Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Payments, 2017	$ 153
Benefit Payments, 2018	159
Benefit Payments, 2019	163
Benefit Payments, 2020	165
Benefit Payments, 2021	166
Benefit Payments, 2022-2026	827
DB Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Payments, 2017	149
Benefit Payments, 2018	155
Benefit Payments, 2019	159
Benefit Payments, 2020	161
Benefit Payments, 2021	161
Benefit Payments, 2022-2026	803
DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Payments, 2017	8
Benefit Payments, 2018	8
Benefit Payments, 2019	9
Benefit Payments, 2020	11
Benefit Payments, 2021	10
Benefit Payments, 2022-2026	50
DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Payments, 2017	5
Benefit Payments, 2018	5
Benefit Payments, 2019	6
Benefit Payments, 2020	7
Benefit Payments, 2021	7
Benefit Payments, 2022-2026	32
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Payments, 2017	59
Benefit Payments, 2018	63
Benefit Payments, 2019	66
Benefit Payments, 2020	69
Benefit Payments, 2021	72
Benefit Payments, 2022-2026	385
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Payments, 2017	57
Benefit Payments, 2018	61
Benefit Payments, 2019	64
Benefit Payments, 2020	67
Benefit Payments, 2021	70
Benefit Payments, 2022-2026	$ 371

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangements Plan Term	10 years
Number of shares authorized	6,500,000
Maximum shares issuable per employee	500,000
Shares available for grant	4,983,931
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangements Plan Term	10 years
Number of shares authorized	6,500,000
Maximum shares issuable per employee	500,000
Shares available for grant	4,983,931
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of Initial Grant Issued on Vesting Date	0.00%
Minimum [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of Initial Grant Issued on Vesting Date	0.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of Initial Grant Issued on Vesting Date	200.00%
Maximum [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of Initial Grant Issued on Vesting Date	200.00%
Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	38 months
Vesting period	3 years
Performance-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	38 months
Vesting period	3 years
Performance-Based Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	36 months
Performance-Based Restricted Stock [Member] | Minimum [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	36 months
Market-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	3 years
Vesting period	3 years
Market-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	3 years
Vesting period	3 years
Time-Lapsed Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	3 years
Time-Lapsed Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	3 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	1 year
Shares forfeited	0	0
Restricted Stock Units (RSUs) [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	1 year
Shares forfeited	0	0

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule Of Restricted Stock Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	841,413
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	801,235
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	826,075
Number of Shares, Vested	(819,658)
Number of Shares, Forfeited	(245,504)
Weighted-Average Grant Date Fair Value per Share, Granted	$ 31.74	$ 36.84	$ 26.15
Weighted-Average Grant Date Fair Value per Share, Vested	24.37
Weighted-Average Grant Date Fair Value per Share, Forfeited	$ 35.18
Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	786,328
Number of Shares, Vested	(782,505)
Number of Shares, Forfeited	(234,523)
Weighted-Average Grant Date Fair Value per Share, Granted	$ 31.77	$ 36.83	$ 26.18
Weighted-Average Grant Date Fair Value per Share, Vested	24.39
Weighted-Average Grant Date Fair Value per Share, Forfeited	$ 35.17
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	15,338
Number of Shares, Vested	(13,588)
Number of Shares, Forfeited	0	0
Weighted-Average Grant Date Fair Value per Share, Granted	$ 39.12	$ 34.25
Weighted-Average Grant Date Fair Value per Share, Vested	$ 33.22
Restricted Stock Units (RSUs) [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,907
Number of Shares, Vested	(13,233)
Number of Shares, Forfeited	0	0
Weighted-Average Grant Date Fair Value per Share, Granted	$ 39.12	$ 34.25
Weighted-Average Grant Date Fair Value per Share, Vested	$ 33.23
Restricted Stock and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, at beginning of period	1,624,934
Number of Shares, at end of period	1,387,597	1,624,934
Weighted-Average Grant Date Fair Value per Share, at beginning of period	$ 29.08
Weighted-Average Grant Date Fair Value per Share, at end of period	$ 32.44	$ 29.08
Restricted Stock and Restricted Stock Units [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, at beginning of period	1,557,657
Number of Shares, at end of period	1,328,631	1,557,657
Weighted-Average Grant Date Fair Value per Share, at beginning of period	$ 29.06
Weighted-Average Grant Date Fair Value per Share, at end of period	$ 32.41	$ 29.06

Stock-Based Compensation (Sc113

Stock-Based Compensation (Schedule Of Restricted Stock Granted) (Details)	12 Months Ended
	Dec. 31, 2016shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	841,413
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	801,235
Time-Lapsed Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	188,303
Time-Lapsed Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	180,958
Market-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	185,464
Market-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	175,818
Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	185,464
Performance-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	175,818
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	15,338
Restricted Stock Units (RSUs) [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,907
Time-Lapsed Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,595
Time-Lapsed Restricted Stock Units [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,186
Dividends On Market-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	38,652
Dividends On Market-Based Awards [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	36,646
Dividends On Performance-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	14,438
Dividends On Performance-Based Awards [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	13,704
Dividends On Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	743
Dividends On Restricted Stock Units [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	721
Additional Market-Based Shares Based On Achievement Of Condition [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	213,754
Additional Market-Based Shares Based On Achievement Of Condition [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	203,384

Stock-Based Compensation (Sc114

Stock-Based Compensation (Schedule Of Share-Based Payment Award, Restricted Stock, Valuation Assumptions) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-Based Compensation [Abstract]
Expected volatility	16.70%	14.10%	15.60%
Expected dividend yield	3.20%	3.30%	3.70%
Risk-free rate	1.00%	0.80%	0.80%

Stock-Based Compensation (Share

Stock-Based Compensation (Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Grants In Period, Weighted Average Grant Date Fair Value) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	$ 31.74	$ 36.84	$ 26.15
Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	31.77	36.83	$ 26.18
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	39.12	34.25
Restricted Stock Units (RSUs) [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	$ 39.12	$ 34.25

Stock-Based Compensation (Sc116

Stock-Based Compensation (Schedule Of Compensation Cost For Share-Based Payment Arrangements, Allocation Of Share-Based Compensation Costs By Plan) (Details) - Restricted Stock [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares that vested during the year	$ 31	$ 29	$ 16
Compensation expense recognized	16	20	14
Income tax benefit recognized	7	8	5
Unrecognized compensation cost	$ 15
Unrecognized compensation cost recognition period	1 year 9 months 18 days
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares that vested during the year	$ 30	28	15
Compensation expense recognized	16	19	13
Income tax benefit recognized	6	$ 7	$ 5
Unrecognized compensation cost	$ 14
Unrecognized compensation cost recognition period	1 year 9 months 18 days

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Benefits [Line Items]
Interest and penalties	$ 0	$ 0	$ 0
IRS audit, adjustments to income tax expense	0
Consumers Energy Company [Member]
Income Tax Benefits [Line Items]
Reduction of income tax expense	39	39	39
Interest and penalties	0	$ 0	$ 0
IRS audit, adjustments to income tax expense	$ 0

Income Taxes (Schedule Of Effec

Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Income from continuing operataions before income taxes		$ 826	$ 796	$ 729
Income tax expense at statutory rate		289	279	255
State and local income taxes, net of federal effect		37	39	36
Accelerated flow-through of regulatory tax benefits	[1]	(39)	(39)	(39)
Employee share-based awards	[2]	(7)
Other, net		(7)	(8)	(2)
Income Tax Expense		$ 273	$ 271	$ 250
Effective tax rate		33.10%	34.00%	34.30%
Consumers Energy Company [Member]
Income Taxes [Line Items]
Income from continuing operataions before income taxes		$ 936	$ 896	$ 873
Income tax expense at statutory rate		328	314	306
State and local income taxes, net of federal effect		44	42	42
Accelerated flow-through of regulatory tax benefits	[1]	(39)	(39)	(39)
Employee share-based awards	[2]	(6)
Other, net		(7)	(15)	(3)
Income Tax Expense		$ 320	$ 302	$ 306
Effective tax rate		34.20%	33.70%	35.10%
[1]	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 $39 million for each of the years ended December 31, 2016, 2015, and 2014.
[2]	CMS Energy and Consumers elected to adopt ASU 2016-09, Improvements to Employee Share-Based Payment Accounting, as of January 1, 2016. For further details on the implementation of this standard, see Note 2, New Accounting Standards.

Income Taxes (Significant Compo

Income Taxes (Significant Components Of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
State and Local	$ 9	$ 24	$ 24
Total Current Income Tax Expense	9	24	24
Federal, deferred income taxes	200	192	198
State and Local, deferred income taxes	47	36	31
Total Deferred Income Tax Expense	247	228	229
Deferred income tax credit	17	19	(3)
Tax Expense	273	271	250
Consumers Energy Company [Member]
Federal	9	66	8
State and Local	22	32	36
Total Current Income Tax Expense	31	98	44
Federal, deferred income taxes	227	153	236
State and Local, deferred income taxes	45	32	29
Total Deferred Income Tax Expense	272	185	265
Deferred income tax credit	17	19	(3)
Tax Expense	$ 320	$ 302	$ 306

Income Taxes (Principal Compone

Income Taxes (Principal Components Of Deferred Income Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Employee benefits	$ (158)	$ (127)
Gas inventory	(65)	(96)
Property, plant and equipment	(2,902)	(2,429)
Net regulatory tax liability	27	50
Reserves and accruals	69	59
Securitized costs	(118)	(122)
Tax loss and credit carryforwards	871	657
Other	(6)	(5)
Gross Deferred Tax Liabilities	(2,282)	(2,013)
Less: valuation allowance	(5)	(4)
Total net deferred income tax liabilities	(2,287)	(2,017)
Deferred tax assets, net of valuation reserves	962	762
Deferred tax liabilities	(3,249)	(2,779)
Consumers Energy Company [Member]
Employee benefits	(181)	(156)
Gas inventory	(65)	(96)
Property, plant and equipment	(2,924)	(2,457)
Net regulatory tax liability	27	50
Reserves and accruals	37	30
Securitized costs	(118)	(122)
Tax loss and credit carryforwards	190	46
Other	(8)	(5)
Total net deferred income tax liabilities	(3,042)	(2,710)
Deferred tax assets, net of valuation reserves	254	126
Deferred tax liabilities	$ (3,296)	$ (2,836)

Income Taxes (Loss And Credit C

Income Taxes (Loss And Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2016USD ($)
Operating Loss Carryforwards [Line Items]
Total tax attributes	$ 871
Consumers Energy Company [Member]
Operating Loss Carryforwards [Line Items]
Total tax attributes	190
Federal Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, Gross Amount	1,415
Federal net operating loss carryforward, Tax Attribute	495
Federal Tax Authority [Member] | Consumers Energy Company [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, Gross Amount	447
Federal net operating loss carryforward, Tax Attribute	157
Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, Gross Amount	408
Local net operating loss carryforwards, Tax Attribute	4
Valuation Allowance - Loss carryforward	2
Alternative Minimum Tax [Member]
Operating Loss Carryforwards [Line Items]
Tax credits, Gross Amount	270
Alternative minimum tax credits, Tax Attribute	270
General Business Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax credits, Gross Amount	102
General business credits, Tax Attribute	102
Valuation Allowance - Loss carryforward	3
General Business Tax Credit Carryforward [Member] | Consumers Energy Company [Member]
Operating Loss Carryforwards [Line Items]
Tax credits, Gross Amount	33
General business credits, Tax Attribute	$ 33

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Beginning And Ending Uncertain Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Balance at beginning of period	$ 6	$ 5	$ 4
Additions for current year tax positions		1	2
Additions for prior year tax positions		1	1
Reductions for prior year tax positions		(1)	(2)
Settlements	(1)
Balance at end of period	5	6	5
Consumers Energy Company [Member]
Balance at beginning of period	6	5	4
Additions for current year tax positions		1	2
Additions for prior year tax positions		1	1
Reductions for prior year tax positions		(1)	(2)
Settlements	(1)
Balance at end of period	$ 5	$ 6	$ 5

Earnings Per Share - CMS Ene123

Earnings Per Share - CMS Energy (Basic And Diluted EPS Computations) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share - CMS Energy [Abstract]
Net income	$ 78		$ 186		$ 125		$ 164		$ 107		$ 148		$ 68		$ 202		$ 553	$ 525	$ 479
Less income attributable to noncontrolling interest	1				1				1				1				2	2	2
Net Income Available to Common Stockholders	$ 77		$ 186		$ 124		$ 164		$ 106		$ 148		$ 67		$ 202		$ 551	$ 523	$ 477
Weighted average shares - basic																	277.9	275.6	270.6
Add dilutive contingently convertible securities																			3.1
Add dilutive non-vested stock awards																	1	0.9	0.9
Weighted average shares - diluted																	278.9	276.5	274.6
Basic	$ 0.28	[1]	$ 0.67	[1]	$ 0.45	[1]	$ 0.59	[1]	$ 0.39	[1]	$ 0.53	[1]	$ 0.25	[1]	$ 0.73	[1]	$ 1.99	$ 1.90	$ 1.76
Diluted	$ 0.28	[1]	$ 0.67	[1]	$ 0.45	[1]	$ 0.59	[1]	$ 0.38	[1]	$ 0.53	[1]	$ 0.25	[1]	$ 0.73	[1]	1.98	1.89	1.74
Dividends Declared Per Common Share																	$ 1.24	$ 1.16	$ 1.08
[1]	The sum of the quarters may not equal annual EPS due to changes in the number of shares outstanding.

Other Income and Other Expen124

Other Income and Other Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fee income	$ 6	$ 9	$ 8
All other	2	1	3
Total other income	8	10	11
Civic and political expenditures	(21)	(10)	(14)
Donations	(23)	(1)	(15)
Loss on reacquired and extinguished debt	(18)		(20)
Unrealized investment loss	(5)
All other	(8)	(6)	(6)
Total other expense	(75)	(17)	(55)
Consumers Energy Company [Member]
Fee income	6	9	8
Gain on CMS Energy common stock		9
All other	2	1	2
Total other income	8	19	10
Civic and political expenditures	(21)	(10)	(14)
Donations	(23)	(1)	(15)
Unrealized investment loss	(4)
All other	(7)	(6)	(6)
Total other expense	$ (55)	$ (17)	$ (35)

Cash And Cash Equivalents (Deta

Cash And Cash Equivalents (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash and cash equivalents	$ 235	$ 266
Restricted cash and cash equivalents	19	19
Other non-current assets	3	3
Cash and cash equivalents, including restricted amounts	257	288	$ 249	$ 204
Consumers Energy Company [Member]
Cash and cash equivalents	131	50
Restricted cash and cash equivalents	19	19
Other non-current assets	2	2
Cash and cash equivalents, including restricted amounts	$ 152	$ 71	$ 112	$ 49

Reportable Segments (Details)

Reportable Segments (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Operating Revenue		$ 1,640	$ 1,587	$ 1,371	$ 1,801	$ 1,509	$ 1,486	$ 1,350	$ 2,111	$ 6,399	$ 6,456	$ 7,179
Depreciation and amortization										811	750	685
Income from equity method investees	[1]									13	14	15
Interest charges										435	396	407
Income tax expense (benefit)										273	271	250
Net Income Attributable to CMS Energy		77	186	124	164	106	148	67	202	551	523	477
Plant, property, and equipment, gross		21,010				18,943				21,010	18,943	17,721
Investments in equity method investees	[1]	65				64				65	64	61
Total Assets		21,622				20,299				21,622	20,299	19,143
Capital expenditures	[2]									1,633	1,741	1,616
Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue		1,550	1,498	1,293	1,723	1,439	1,417	1,281	2,028	6,064	6,165	6,800
Depreciation and amortization										803	744	678
Interest charges										268	250	250
Income tax expense (benefit)										320	302	306
Net income (loss) available to common stockholder		116	$ 195	$ 131	$ 172	134	$ 160	$ 83	$ 215	614	592	565
Plant, property, and equipment, gross		20,838				18,797				20,838	18,797	17,580
Total Assets		19,946				18,635				19,946	18,635	17,824
Capital expenditures	[2]									1,618	1,694	1,612
Electric Utility [Member]
Segment Reporting Information [Line Items]
Operating Revenue										4,379	4,249	4,436
Depreciation and amortization										603	567	522
Interest charges										196	178	181
Income tax expense (benefit)										246	224	211
Net Income Attributable to CMS Energy										458	437	384
Plant, property, and equipment, gross		14,540				13,059				14,540	13,059	12,230
Total Assets	[3]	13,429				12,660				13,429	12,660	11,565
Capital expenditures	[2]									1,007	1,136	1,139
Electric Utility [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue										4,379	4,249	4,436
Depreciation and amortization										603	567	522
Interest charges										196	178	181
Income tax expense (benefit)										246	224	211
Net income (loss) available to common stockholder										458	437	384
Plant, property, and equipment, gross		14,540				13,059				14,540	13,059	12,230
Total Assets	[3]	13,430				12,660				13,430	12,660	11,565
Capital expenditures	[2]									1,007	1,136	1,139
Gas Utility [Member]
Segment Reporting Information [Line Items]
Operating Revenue										1,685	1,916	2,363
Depreciation and amortization										200	177	156
Interest charges										72	71	67
Income tax expense (benefit)										74	78	95
Net Income Attributable to CMS Energy										155	154	179
Plant, property, and equipment, gross		6,283				5,723				6,283	5,723	5,335
Total Assets	[3]	6,446				5,912				6,446	5,912	5,385
Capital expenditures	[2]									611	558	473
Gas Utility [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue										1,685	1,916	2,363
Depreciation and amortization										200	177	156
Interest charges										72	71	67
Income tax expense (benefit)										74	78	95
Net income (loss) available to common stockholder										155	154	179
Plant, property, and equipment, gross		6,283				5,723				6,283	5,723	5,335
Total Assets	[3]	6,446				5,912				6,446	5,912	5,385
Capital expenditures	[2]									611	558	473
Enterprises [Member]
Segment Reporting Information [Line Items]
Operating Revenue										215	190	299
Depreciation and amortization										5	4	4
Income from equity method investees	[1]									13	14	15
Interest charges										1
Income tax expense (benefit)										10	3	(1)
Net Income Attributable to CMS Energy										17	4	(1)
Plant, property, and equipment, gross		157				120				157	120	115
Investments in equity method investees	[1]	62				61				62	61	58
Total Assets		269				270				269	270	231
Capital expenditures	[2]									10	44	3
Other [Member]
Segment Reporting Information [Line Items]
Operating Revenue										120	101	81
Depreciation and amortization										3	2	3
Interest charges										166	147	159
Income tax expense (benefit)										(57)	(34)	(55)
Net Income Attributable to CMS Energy										(79)	(72)	(85)
Plant, property, and equipment, gross		30				41				30	41	41
Investments in equity method investees	[1]	3				3				3	3	3
Total Assets		1,478				1,457				1,478	1,457	1,962
Capital expenditures	[2]									5	3	1
Other [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue												1
Interest charges											1	2
Net income (loss) available to common stockholder										1	1	2
Plant, property, and equipment, gross		15				15				15	15	15
Total Assets		$ 70				$ 63				$ 70	$ 63	$ 874
[1]	Consumers had no significant equity method investments.
[2]	Amounts include purchase of capital lease additions. Amounts also include a portion of Consumers' capital expenditures for plant and equipment attributable to both the electric and gas utility businesses.
[3]	Amounts include a portion of Consumers' other common assets attributable to both the electric and gas utility businesses.

Related Party Transactions -127

Related Party Transactions - Consumers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Purchased power - related parties	$ 86	$ 83	$ 90
Accounts payable - related parties	12	9
Accounts receivable - related parties	12	11
Consumers Energy Company [Member]
Related Party Transaction [Line Items]
Purchased power - related parties	88	83	$ 89
Accounts payable - related parties	18	15
Accounts receivable - related parties	9	17
Due to related parties	24	23
Investments	33	$ 29
Future purchase power, related parties	4
Consumers Energy Company [Member] | Credit Agreement [Member]
Related Party Transaction [Line Items]
Maximum borrowing capacity	300
Amount outstanding	$ 0

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	$ 62	$ 61
Genesee [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	8
Guarantee of Indebtedness of Others [Member] | Genesee [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 3

Variable Interest Entities (Sch

Variable Interest Entities (Schedule Of Variable Interest Entities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
T.E.S. Filer City [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	50.00%
Grayling [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	50.00%
Genesee [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	50.00%
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 8
Genesee [Member] | Guarantee of Indebtedness of Others [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 3
Craven [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	50.00%

Quarterly Financial And Comm130

Quarterly Financial And Common Stock Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended																12 Months Ended
		Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Operating Revenue		$ 1,640		$ 1,587		$ 1,371		$ 1,801		$ 1,509		$ 1,486		$ 1,350		$ 2,111		$ 6,399	$ 6,456	$ 7,179
Operating Income (Loss)		290		386		285		336		245		317		204		397		1,297	1,163	1,152
Net Income		78		186		125		164		107		148		68		202		553	525	479
Income Attributable to Noncontrolling Interests		1				1				1				1				2	2	2
Net income attributable to CMS Energy		$ 77		$ 186		$ 124		$ 164		$ 106		$ 148		$ 67		$ 202		$ 551	$ 523	$ 477
Basic Earnings Per Average Common Share		$ 0.28	[1]	$ 0.67	[1]	$ 0.45	[1]	$ 0.59	[1]	$ 0.39	[1]	$ 0.53	[1]	$ 0.25	[1]	$ 0.73	[1]	$ 1.99	$ 1.90	$ 1.76
Diluted Earnings Per Average Common Share		$ 0.28	[1]	$ 0.67	[1]	$ 0.45	[1]	$ 0.59	[1]	$ 0.38	[1]	$ 0.53	[1]	$ 0.25	[1]	$ 0.73	[1]	$ 1.98	$ 1.89	$ 1.74
CMS Energy [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Operating Income (Loss)																		$ (15)	$ (9)	$ (6)
Net Income																		551	523	477
Net income attributable to CMS Energy																		551	523	477
Consumers Energy Company [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Operating Revenue		$ 1,550		$ 1,498		$ 1,293		$ 1,723		$ 1,439		$ 1,417		$ 1,281		$ 2,028		6,064	6,165	6,800
Operating Income (Loss)		288		365		264		317		246		305		192		379		1,234	1,122	1,135
Net Income		117		195		132		172		135		160		84		215		616	594	567
Preferred stock dividends		1				1				1				1				2	2	2
Net income (loss) available to common stockholder		$ 116		$ 195		$ 131		$ 172		$ 134		$ 160		$ 83		$ 215		$ 614	$ 592	$ 565
Maximum [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Share price	[2]	$ 42.15		$ 46.17		$ 45.86		$ 42.44		$ 37.17		$ 35.82		$ 35.57		$ 38.20		$ 42.15	$ 37.17
Minimum [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Share price	[2]	$ 39.49		$ 41.31		$ 39.38		$ 35.61		$ 34.24		$ 32.10		$ 31.39		$ 32.83		$ 39.49	$ 34.24
[1]	The sum of the quarters may not equal annual EPS due to changes in the number of shares outstanding.
[2]	Based on New York Stock Exchange composite transactions.

Schedule I - Condensed Finan131

Schedule I - Condensed Financial Information of Registrant (Condensed Statements of Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other operating expense									$ (1,207)	$ (1,238)	$ (1,232)
General taxes									281	262	252
Total operating expenses									(5,102)	(5,293)	(6,027)
Operating Loss	$ 290	$ 386	$ 285	$ 336	$ 245	$ 317	$ 204	$ 397	1,297	1,163	1,152
Interest income									6	12	5
Total other income									(36)	29	(16)
Interest on long-term debt									411	386	393
Intercompany interest expense and other									29	14	17
Total interest charges									435	396	407
Income Before Income Taxes									826	796	729
Income Tax Expense									273	271	250
Net income attributable to CMS Energy	$ 77	$ 186	$ 124	$ 164	$ 106	$ 148	$ 67	$ 202	551	523	477
CMS Energy [Member]
Other operating expense									(15)	(9)	(6)
Total operating expenses									(15)	(9)	(6)
Operating Loss									(15)	(9)	(6)
Equity earnings of subsidiaries									660	625	585
Interest income									1	1	1
Other expense									(19)	(9)	(20)
Total other income									642	617	566
Interest on long-term debt									150	134	150
Intercompany interest expense and other									1	3	2
Total interest charges									151	137	152
Income Before Income Taxes									476	471	408
Income Tax Expense									(75)	(52)	(69)
Net income attributable to CMS Energy									$ 551	$ 523	$ 477

Schedule I - Condensed Finan132

Schedule I - Condensed Financial Information of Registrant (Condensed Statements Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Income	$ 78	$ 186	$ 125	$ 164	$ 107	$ 148	$ 68	$ 202	$ 553	$ 525	$ 479
Deferred income taxes									247	228	229
Other non-cash operating activities and reconciling adjustments									52	100	58
Accounts and notes receivable									(155)	120	(31)
Accounts payable									59	(26)	50
Other current and non-current assets and liabilities									(43)	(19)	1
Net cash provided by operating activities									1,629	1,640	1,481
Net cash used in investing activities									(1,915)	(2,064)	(1,898)
Proceeds from issuance of debt									1,049	599	1,428
Issuance of common stock									72	43	43
Retirement of long-term debt									(728)	(224)	(750)
Debt prepayment costs									(18)		(36)
Increase (decrease) in notes payable									149	189	(110)
Net cash provided by (used in) financing activities									255	463	462
Net Increase in Cash and Cash Equivalents, Including Restricted Amounts									(31)	39	45
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period				288				249	288	249	204
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	257				288				257	288	249
CMS Energy [Member]
Net Income									551	523	477
Equity earnings of subsidiaries									(660)	(625)	(585)
Dividends received from subsidiaries									499	499	544
Deferred income taxes									(26)	(24)	30
Other non-cash operating activities and reconciling adjustments									18		20
Accounts and notes receivable									85	(86)	(3)
Accounts payable									(9)	16	(2)
Accrued taxes									(74)	(115)	97
Other current and non-current assets and liabilities									38	21	31
Net cash provided by operating activities									422	209	609
Investment in subsidiaries									(275)	(150)	(495)
Return of capital											178
Net cash used in investing activities									(275)	(150)	(317)
Proceeds from issuance of debt									603	349	550
Issuance of common stock									72	43	43
Retirement of long-term debt									(530)	(100)	(547)
Debt prepayment costs									(18)		(20)
Payment of dividends on common stock									(345)	(320)	(293)
Debt issuance costs and financing fees									(5)	(3)	(6)
Increase (decrease) in notes payable									76	(28)	(19)
Net cash provided by (used in) financing activities									(147)	(59)	(292)
Net Increase in Cash and Cash Equivalents, Including Restricted Amounts
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period
Cash and Cash Equivalents, Including Restricted Amounts, End of Period

Schedule I - Condensed Finan133

Schedule I - Condensed Financial Information of Registrant (Condensed Balance Sheets) (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Notes and accrued interest receivable		$ 180	$ 128
Accounts receivable, including intercompany and related parties		12	11
Prepayments and other current assets		81	77
Total current assets		2,280	2,320
Less accumulated depreciation and amortization		6,056	5,747
Total plant, property, and equipment	[1]	15,715	14,705
Other		353	343
Total other non-current assets		3,627	3,274
Total Assets		21,622	20,299	$ 19,143
Current portion of long-term debt		886	706
Accounts and notes payable, including intercompany and related parties		12	9
Accrued interest, including intercompany		98	106
Accrued taxes		348	349
Other liabilities current		199	142
Total current liabilities		2,655	2,302
Long-term debt		8,640	8,400
Net unamortized discounts		(15)	(12)
Postretirement benefits		789	591
Other non-current liabilities		290	313
Total non-current liabilities		14,677	14,022
Common stockholders' equity		4,253	3,938
Total Liabilities and Equity		21,622	20,299
CMS Energy [Member]
Notes and accrued interest receivable		2	88
Accounts receivable, including intercompany and related parties		7	9
Accrued taxes		51
Prepayments and other current assets		1
Total current assets		61	97
Plant, property, and equipment, gross			16
Less accumulated depreciation and amortization			16
Total plant, property, and equipment
Noncurrent notes receivable		3
Deferred income taxes		366	340
Invetment in subsidiaries		6,674	6,240
Other investments - DB SERP		26	26
Other		4	5
Total other non-current assets		7,073	6,611
Total Assets		7,134	6,708
Accounts and notes payable, including intercompany and related parties		141	74
Accrued interest, including intercompany		28	38
Accrued taxes			23
Other liabilities current		10	5
Total current liabilities		179	140
Long-term debt		2,678	2,605
Postretirement benefits		21	22
Other non-current liabilities		3	3
Total non-current liabilities		2,702	2,630
Common stockholders' equity		4,253	3,938
Total Liabilities and Equity		$ 7,134	$ 6,708
[1]	For the year ended December 31, 2016, Consumers' plant additions were $2.3 billion and plant retirements were $285 million. For the year ended December 31, 2015, Consumers' plant additions were $1.4 billion and plant retirements were $187 million.

Schedule I - Condensed Finan134

Schedule I - Condensed Financial Information of Registrant (Narrative) (Details) $ in Millions	Dec. 31, 2016USD ($)
CMS Energy [Member]
Maximum potential obligation	$ 324

Schedule II - Valuation and 135

Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Uncollectible Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	[1]	$ 28	$ 40	$ 33
Charged to Expense	[1]	31	50	72
Charged to other Accounts	[1]
Deductions	[1]	35	62	65
Balance at End of Period	[1]	24	28	40
Allowance for Uncollectible Accounts [Member] | Consumers Energy Company [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		28	39	31
Charged to Expense		31	50	72
Charged to other Accounts
Deductions		35	61	64
Balance at End of Period		24	28	39
Deferred Tax Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		4	2	2
Charged to Expense		1	3
Charged to other Accounts			(1)
Deductions
Balance at End of Period		5	4	2
Deferred Tax Valuation Allowance [Member] | Consumers Energy Company [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period			1	1
Charged to Expense
Charged to other Accounts			(1)
Deductions
Balance at End of Period				1
Allowance For Notes Receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	[1]	9	8	5
Charged to Expense	[1]	19	8	8
Charged to other Accounts	[1]
Deductions	[1]	12	7	5
Balance at End of Period	[1]	$ 16	$ 9	$ 8
[1]	Deductions are write-offs of uncollectible accounts, net of recoveries.