Consumers Energy (CMS-PB) 10-K 11 Feb 16 2015 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Jan. 13, 2016	Jun. 30, 2015
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2,015
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			$ 8,736
CMS Energy [Member]
Entity Common Stock, Shares Outstanding		277,970,146
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, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Revenue		$ 6,456	$ 7,179	$ 6,566
Operating Expenses
Fuel for electric generation		593	673	621
Purchased and interchange power		1,406	1,602	1,387
Purchased power - related parties		83	90	90
Cost of gas sold		961	1,493	1,228
Maintenance and other operating expenses		1,238	1,232	1,236
Depreciation and amortization		750	685	628
General taxes		262	252	234
Total operating expenses		5,293	6,027	5,424
Operating Income		1,163	1,152	1,142
Other Income (Expense)
Interest income		12	5	3
Allowance for equity funds used during construction		10	8	6
Income from equity method investees	[1]	14	15	13
Other income		10	11	10
Other expense		(17)	(55)	(20)
Total other income (expense)		29	(16)	12
Interest Charges
Interest on long-term debt		386	393	385
Other interest expense		14	17	16
Allowance for borrowed funds used during construction		(4)	(3)	(3)
Total interest charges		396	407	398
Income Before Income Taxes		796	729	756
Income Tax Expense		271	250	302
Net Income		525	479	454
Income Attributable to Noncontrolling Interests		2	2	2
Net Income Available to Common Stockholders		$ 523	$ 477	$ 452
Basic Earnings Per Average Common Share		$ 1.90	$ 1.76	$ 1.71
Diluted Earnings Per Average Common Share		$ 1.89	$ 1.74	$ 1.66
Consumers Energy Company [Member]
Operating Revenue		$ 6,165	$ 6,800	$ 6,321
Operating Expenses
Fuel for electric generation		497	567	541
Purchased and interchange power		1,376	1,564	1,361
Purchased power - related parties		83	89	89
Cost of gas sold		939	1,375	1,187
Maintenance and other operating expenses		1,149	1,146	1,174
Depreciation and amortization		744	678	622
General taxes		255	246	229
Total operating expenses		5,043	5,665	5,203
Operating Income		1,122	1,135	1,118
Other Income (Expense)
Interest income		11	4	2
Interest and dividend income - related parties		1	1	1
Allowance for equity funds used during construction		10	8	6
Other income		19	10	14
Other expense		(17)	(35)	(16)
Total other income (expense)		24	(12)	7
Interest Charges
Interest on long-term debt		252	243	237
Other interest expense		2	10	11
Allowance for borrowed funds used during construction		(4)	(3)	(3)
Total interest charges		250	250	245
Income Before Income Taxes		896	873	880
Income Tax Expense		302	306	346
Net Income		594	567	534
Preferred Stock Dividends and Distribution		2	2	2
Net Income Available to Common Stockholders		$ 592	$ 565	$ 532
[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, 2015	Dec. 31, 2014	Dec. 31, 2013
Net income	$ 525	$ 479	$ 454
Retirement Benefits Liability
Net gain (loss) arising during the period, net of tax	1	(29)	26
Prior service credit adjustment, net of tax			5
Amortization of net actuarial loss (gain), net of tax	5	3	4
Amortization of prior service credit, net of tax	(1)	(1)
Investments
Unrealized gain (loss) on investments, net of tax	(3)	(1)	(2)
Derivative Instruments
Reclassification adjustments included in net income, net of tax		1
Other Comprehensive Income (Loss)	2	(27)	33
Comprehensive Income	527	452	487
Comprehensive Income Attributable to Noncontrolling Interest	2	2	2
Comprehensive Income Attributable to CMS Energy	525	450	485
Consumers Energy Company [Member]
Net income	594	567	534
Retirement Benefits Liability
Net gain (loss) arising during the period, net of tax	3	(11)	5
Amortization of net actuarial loss (gain), net of tax	4	2	3
Investments
Unrealized gain (loss) on investments, net of tax	(1)	4	1
Reclassification adjustments included in net income, net of tax	(5)		(3)
Derivative Instruments
Other Comprehensive Income (Loss)	1	(5)	6
Comprehensive Income Attributable to CMS Energy	$ 595	$ 562	$ 540

Consolidated Statements Of Com4

Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net gain (loss) arising during the period, tax		$ (18)	$ 16
Tax on prior service credit adjustment			3
Amortization of net actuarial loss, tax	$ 4	$ 1	$ 3
Amortization of prior service credit, tax
Unrealized gain (loss) on investments, tax expense (tax benefit)	$ (1)	$ (1)	$ (1)
Consumers Energy Company [Member]
Net gain (loss) arising during the period, tax	2	(7)	4
Amortization of net actuarial loss, tax	2	1	2
Unrealized gain (loss) on investments, tax expense (tax benefit)	(1)	$ 2
Reclassification adjustments included in net income, tax	$ (3)		$ (1)

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows from Operating Activities
Net income	$ 525	$ 479	$ 454
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	750	685	628
Deferred income taxes and investment tax credit	247	227	268
Postretirement benefits expense	91	23	144
Bad debt expense	58	80	67
Other non-cash operating activities	9	17	22
Postretirement benefits contributions	(262)	(32)	(229)
Proceeds from government grant			69
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	120	(31)	(120)
Decrease (increase) in inventories	147	(36)	202
Increase (decrease) in accounts payable and accrued refunds	(26)	50	4
Other current and non-current assets and liabilities	(19)	(15)	(88)
Net cash provided by operating activities	1,640	1,447	1,421
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,564)	(1,577)	(1,325)
Jackson plant acquisition	(154)
Cost to retire property	(89)	(75)	(56)
Increase in EnerBank notes receivable	(279)	(255)	(139)
Proceeds from the sale of EnerBank notes receivable	48
Other investing activities	(6)	(3)	(12)
Net cash used in investing activities	(2,044)	(1,910)	(1,532)
Cash Flows from Financing Activities
Proceeds from issuance of debt	599	1,428	1,025
Net increase in EnerBank certificates of deposit	214	233	125
Issuance of common stock	43	43	36
Retirement of long-term debt	(224)	(750)	(741)
Payment of dividends on common and preferred stock	(322)	(295)	(273)
Increase (decrease) in notes payable	189	(110)	60
Payment of capital lease obligations and other financing costs	(36)	(51)	(42)
Net cash provided by financing activities	463	498	190
Net Increase in Cash and Cash Equivalents	59	35	79
Cash and Cash Equivalents, Beginning of Period	207	172	93
Cash and Cash Equivalents, End of Period	266	207	172
Cash transactions
Interest paid (net of amounts capitalized)	386	380	382
Income taxes paid (refunds received), net	10	22	34
Non-Cash Transactions
Capital expenditures not paid	201	201	176
Other assets placed under capital lease	17	7	6
Consumers Energy Company [Member]
Cash Flows from Operating Activities
Net income	594	567	534
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	744	678	622
Deferred income taxes and investment tax credit	204	263	164
Postretirement benefits expense	90	24	142
Bad debt expense	50	72	63
Other non-cash operating activities	8	10	12
Postretirement benefits contributions	(243)	(29)	(222)
Proceeds from government grant			69
Cash provided by (used in) changes in assets and liabilities
Decrease (increase) in accounts receivable, notes receivable, and accrued revenue	104	(16)	(116)
Decrease (increase) in inventories	144	(36)	205
Increase (decrease) in accounts payable and accrued refunds	(22)	47	12
Other current and non-current assets and liabilities	121	(242)	(134)
Net cash provided by operating activities	1,794	1,338	1,351
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under capital lease)	(1,537)	(1,573)	(1,320)
Jackson plant acquisition	(154)
Cost to retire property	(89)	(75)	(56)
Other investing activities	(1)	(5)	(11)
Net cash used in investing activities	(1,781)	(1,653)	(1,387)
Cash Flows from Financing Activities
Proceeds from issuance of debt	250	878	750
Retirement of long-term debt	(124)	(220)	(466)
Payment of dividends on common and preferred stock	(476)	(459)	(408)
Stockholder contribution	150	495	150
Return of stockholder contribution		(178)
Increase (decrease) in notes payable	189	(110)	60
Payment of capital lease obligations and other financing costs	(23)	(38)	(37)
Net cash provided by financing activities	(34)	368	49
Net Increase in Cash and Cash Equivalents	(21)	53	13
Cash and Cash Equivalents, Beginning of Period	71	18	5
Cash and Cash Equivalents, End of Period	50	71	18
Cash transactions
Interest paid (net of amounts capitalized)	245	233	236
Income taxes paid (refunds received), net	(84)	266	225
Non-Cash Transactions
Capital expenditures not paid	182	201	176
Other assets placed under capital lease	$ 17	$ 7	$ 6

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents		$ 266	$ 207
Restricted cash and cash equivalents		19	37
Accounts receivable and accrued revenue, less allowances		774	881
Notes receivable, less allowances		128	98
Notes receivable held for sale		16	41
Accounts receivable - related parties		$ 11	11
Accrued gas revenue			27
Inventories at average cost
Gas in underground storage		$ 568	681
Materials and supplies		126	117
Generating plant fuel stock		84	120
Deferred property taxes		235	216
Regulatory assets		16	89
Prepayments and other current assets		77	72
Total current assets		2,320	2,597
Plant, Property, and Equipment
Plant, property, and equipment, gross		18,943	17,721
Less accumulated depreciation and amortization		5,747	5,415
Plant, property, and equipment, net		13,196	12,306
Construction work in progress		1,509	1,106
Total plant, property, and equipment	[1]	14,705	13,412
Other Non-current Assets
Regulatory assets		1,840	1,956
Accounts and notes receivable		1,027	807
Investments	[2]	64	61
Other		384	352
Total other non-current assets		3,315	3,176
Total Assets		20,340	19,185
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation		706	540
Notes payable		249	60
Accounts payable		633	678
Accounts payable - related parties, current		9	10
Accrued rate refunds		26	6
Accrued interest		106	108
Accrued taxes		349	316
Regulatory liabilities		82	67
Other current liabilities		142	163
Total current liabilities		2,302	1,948
Non-current Liabilities
Long-term debt		8,441	8,016
Non-current portion of capital leases and financing obligation		118	123
Regulatory liabilities		2,088	2,095
Postretirement benefits		591	872
Asset retirement obligations		439	340
Deferred investment tax credit		56	37
Deferred income taxes		2,017	1,748
Other non-current liabilities		313	299
Total non-current liabilities		$ 14,063	$ 13,530
Commitments and Contingencies (Notes 3, 4, and 5)
Common stockholder's equity
Common stock		$ 3	$ 3
Other paid-in capital		4,837	4,774
Accumulated other comprehensive loss		(47)	(49)
Retained earnings (Accumulated deficit)		(855)	(1,058)
Total common stockholders' equity		3,938	3,670
Noncontrolling interests		37	37
Total equity		3,975	3,707
Total Liabilities and Equity		20,340	19,185
Consumers Energy Company [Member]
Current Assets
Cash and cash equivalents		50	71
Restricted cash and cash equivalents		19	37
Accounts receivable and accrued revenue, less allowances		758	863
Accounts receivable - related parties		17	1
Accrued gas revenue			27
Inventories at average cost
Gas in underground storage		568	681
Materials and supplies		120	113
Generating plant fuel stock		80	112
Deferred property taxes		235	216
Regulatory assets		16	89
Prepayments and other current assets		66	63
Total current assets		1,929	2,273
Plant, Property, and Equipment
Plant, property, and equipment, gross		18,797	17,580
Less accumulated depreciation and amortization		5,676	5,346
Plant, property, and equipment, net		13,121	12,234
Construction work in progress		1,467	1,103
Total plant, property, and equipment	[1]	14,588	13,337
Other Non-current Assets
Regulatory assets		1,840	1,956
Accounts and notes receivable		10	7
Investments		29	38
Other		262	236
Total other non-current assets		2,141	2,237
Total Assets		18,658	17,847
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation		220	145
Notes payable		249	60
Accounts payable		613	662
Accounts payable - related parties, current		15	12
Accrued rate refunds		26	6
Accrued interest		65	70
Accrued taxes		352	149
Regulatory liabilities		82	67
Other current liabilities		109	135
Total current liabilities		1,731	1,306
Non-current Liabilities
Long-term debt		5,206	5,154
Non-current portion of capital leases and financing obligation		118	123
Regulatory liabilities		2,088	2,095
Postretirement benefits		529	793
Asset retirement obligations		438	339
Deferred investment tax credit		56	37
Deferred income taxes		2,710	2,486
Other non-current liabilities		236	237
Total non-current liabilities		$ 11,381	$ 11,264
Commitments and Contingencies (Notes 3, 4, and 5)
Common stockholder's equity
Common stock		$ 841	$ 841
Other paid-in capital		3,724	3,574
Accumulated other comprehensive loss		(6)	(7)
Retained earnings (Accumulated deficit)		950	832
Total common stockholders' equity		5,509	5,240
Preferred stock		37	37
Total equity		5,546	5,277
Total Liabilities and Equity		$ 18,658	$ 17,847
[1]	For the year ended December 31, 2015, utility plant additions were $1.4 billion and utility plant retirements were $187 million. For the year ended December 31, 2014, utility plant additions were $1.6 billion and utility plant retirements were $126 million.
[2]	Consumers had no significant equity method investments.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Allowances for doubtful accounts receivable	$ 28	$ 40
Allowances for doubtful notes receivable	$ 9	$ 8
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares outstanding	277,200,000	275,200,000
Consumers Energy Company [Member]
Allowances for doubtful accounts receivable	$ 28	$ 39
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 ($) shares in Thousands, $ 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, 2012	$ 841	$ 3,107	$ (8)	$ (25)	$ 17	$ 598	$ 44	$ 4,582	$ 3	$ 4,669	$ (55)	$ (56)	$ 2	$ (1)	$ (1,423)	$ 44	$ 3,238
Beginning of period, shares at Dec. 31, 2012									264,072
Common stock issued										51
Number of Shares Issued									2,238
Common stock repurchased										(10)
Common stock repurchased, shares									(356)
Common stock reissued										$ 5
Common stock reissued, shares									205
Conversion option on convertible debt
Common stock reacquired, value
Common stock reacquired, shares									(22)
Stockholder contribution		$ 150
Return of stockholder contribution
Net gain arising during the period				5				5				26					26
Prior service credit adjustment												5					5
Amortization of net actuarial loss (gain)				3				3				4					4
Unrealized gain (loss) on investments, net of tax					1			1					$ (2)				(2)
Reclassification adjustments included in net income, net of tax					(3)			3
Reclassification adjustments included in net income
Net income (loss) attributable to CMS Energy															452		452
Net income						534		534									454
Dividends declared on common stock						(406)									(271)
Preferred stock dividends and distributions declared						(2)
Income Attributable to Noncontrolling Interests																2	2
Distributions, redemptions, and other changes in noncontrolling interests																(9)
Preferred stock redeemed							(7)
End of period, shares at Dec. 31, 2013									266,137
Total Equity, end 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
Common stock issued										59
Number of Shares Issued									9,371
Common stock repurchased										$ (7)
Common stock repurchased, shares									(271)
Common stock reissued
Common stock reissued, shares
Conversion option on convertible debt										$ 7
Common stock reacquired, value
Common stock reacquired, shares									(53)
Stockholder contribution		495
Return of stockholder contribution		(178)
Net gain arising during the period				(11)				(11)				$ (29)					(29)
Prior service credit adjustment
Amortization of net actuarial loss (gain)				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, net of tax
Reclassification adjustments included in net income														$ 1			(1)
Net income (loss) attributable to CMS Energy															477		477
Net income						567		$ 567									479
Dividends declared on common stock						(457)									(293)
Preferred stock dividends and distributions declared						(2)
Income Attributable to Noncontrolling Interests																2	$ 2
Distributions, redemptions, and other changes in noncontrolling interests																(2)
Preferred stock redeemed
End of period, shares at Dec. 31, 2014								84,100	275,184								275,200
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
Number of Shares Issued									2,062
Common stock repurchased										(12)
Common stock repurchased, shares									(306)
Common stock reissued										$ 10
Common stock reissued, shares									288
Conversion option on convertible debt
Common stock reacquired, value
Common stock reacquired, shares									(65)
Stockholder contribution		$ 150
Return of stockholder contribution
Net gain arising during the period				3				3				$ 1					1
Prior service credit adjustment
Amortization of net actuarial loss (gain)				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, net of tax					(5)			5
Reclassification adjustments included in net income
Net income (loss) attributable to CMS Energy															523		523
Net income						594		$ 594									525
Dividends declared on common stock						(474)									(320)
Preferred stock dividends and distributions declared						(2)
Income Attributable to Noncontrolling Interests																2	$ 2
Distributions, redemptions, and other changes in noncontrolling interests																(2)
Preferred stock redeemed
End of period, shares at Dec. 31, 2015								84,100	277,163								277,200
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

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
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: In 2009, the MPSC approved an energy optimization incentive mechanism that 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. 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. 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, which is recorded as a reduction to notes receivable on CMS Energy’s consolidated balance sheets, was $82 million at December 31, 2015 and $62 million at December 31, 2014. 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. Cash and Cash Equivalents: Cash and cash equivalents include short-term, highly liquid investments with original maturities of three months or less. 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. 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. 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 because: · 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. CMS Energy and Consumers did not have significant amounts recorded as derivative assets or liabilities at December 31, 2015 or 2014 . Additionally, the gains and losses recognized in earnings were insignificant for the years ended December 31, 2015 , 2014 , and 2013 . Determination of MRV of Plan Assets for DB Pension Plan and OPEB Plan: CMS Energy and Consumers determine the MRV 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. CMS Energy and Consumers use the MRV in the calculation of net DB Pension Plan and OPEB Plan costs. For further details, see Note 12, Retirement Benefits. 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 use the lower-of-cost-or-market method to evaluate inventory for impairment. 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. Consumers recorded the deferred income taxes related to the grant as a reduction of the book basis of Lake Winds ® Energy Park. Restricted Cash and Cash Equivalents: CMS Energy and Consumers have restricted cash and cash equivalents dedicated for repayment of Securitization bonds and for payment under performance guarantees. CMS Energy and Consumers classify these amounts as a current asset if they relate to payments that could or will occur within one year. Changes in restricted cash and cash equivalents are presented as investing activities on the consolidated statements of cash flows.
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: In 2009, the MPSC approved an energy optimization incentive mechanism that 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. 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. 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, which is recorded as a reduction to notes receivable on CMS Energy’s consolidated balance sheets, was $82 million at December 31, 2015 and $62 million at December 31, 2014. 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. Cash and Cash Equivalents: Cash and cash equivalents include short-term, highly liquid investments with original maturities of three months or less. 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. 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. 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 because: · 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. CMS Energy and Consumers did not have significant amounts recorded as derivative assets or liabilities at December 31, 2015 or 2014 . Additionally, the gains and losses recognized in earnings were insignificant for the years ended December 31, 2015 , 2014 , and 2013 . Determination of MRV of Plan Assets for DB Pension Plan and OPEB Plan: CMS Energy and Consumers determine the MRV 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. CMS Energy and Consumers use the MRV in the calculation of net DB Pension Plan and OPEB Plan costs. For further details, see Note 12, Retirement Benefits. 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 use the lower-of-cost-or-market method to evaluate inventory for impairment. 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. Consumers recorded the deferred income taxes related to the grant as a reduction of the book basis of Lake Winds ® Energy Park. Restricted Cash and Cash Equivalents: CMS Energy and Consumers have restricted cash and cash equivalents dedicated for repayment of Securitization bonds and for payment under performance guarantees. CMS Energy and Consumers classify these amounts as a current asset if they relate to payments that could or will occur within one year. Changes in restricted cash and cash equivalents are presented as investing activities on the consolidated statements of cash flows.

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2015
New Accounting Standards	2: New Accounting Standards Implementation of New Accounting Standards ASU 2015 ‑13, Application of the Normal Purchases and Normal Sales Scope Exception to Certain Electricity Contracts within Nodal Energy Markets: This standard, which became effective in August 2015 for CMS Energy and Consumers, was intended to resolve diversity in practice regarding whether certain electricity contracts are eligible for the normal purchases and sales scope exception from derivative accounting. The standard clarifies that contracts that require transmission of electricity through a market with established price points at each node or hub location are eligible for the scope exception. Consumers applies the normal purchases and sales scope exception to many PPAs that require transmission of electricity through the MISO market, which has price points at various node or hub locations. Since this standard clarifies that these contracts are eligible for the scope exception, which is consistent with Consumers’ treatment, the standard had no impact on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2015 ‑17, Balance Sheet Classification of Deferred Taxes: This standard eliminates the requirement to separate deferred income tax assets and liabilities into current and non ‑ current amounts on a classified balance sheet. Under the standard, all deferred income tax amounts should be classified as non ‑ current. The standard will be effective on January 1, 2017 for CMS Energy and Consumers, but early adoption is permitted. The standard can be applied either prospectively or retrospectively. CMS Energy and Consumers elected to adopt the standard early for the year ended Decemb er 31, 2015 and applied the standard retrospectively to all prior periods. Accordingly, CMS Energy reclassified $66 million of current deferred income tax liabilities to non ‑current deferred income tax li abilities at December 31, 2014, and Consumers reclassified $80 million of current deferred income tax liabilities to non ‑ current deferred income tax liabilities at December 31, 2014. New Accounting Standards Not Yet Effective ASU 2014 ‑09, Revenue from Contracts with Customers: This standard, which will become effective January 1, 2018 for CMS Energy and Consumers, 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. Entities will have the option to apply the standard retrospectively to all prior periods presented, or to apply it retrospectively only to contracts existing at the effective date, with the cumulative effect of the standard recorded as an adjustment to beginning retained earnings. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements. 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, effective 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 intended 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 apply to awards of this type. Therefore, CMS Energy and Consumers do not expect the standard to impact their consolidated financial statements. ASU 2015 ‑02, Amendments to the Consolidation Analysis: This standard, effective 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 have assessed this standard and do not expect that it will result in any changes to their consolidation conclusions or have any impact on their consolidated income, cash flows, or financial position. ASU 2015 ‑03, Simplifying the Presentation of Debt Issuance Costs: This standard, effective 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. Presently, debt issuance costs are reported as an asset. The new guidance aligns the presentation of debt issuance costs with debt discounts and premiums. The standard is to be applied retrospectively to all prior periods presented. At December 31, 2015 , CMS Energy had $41 million of unamortized debt issuance costs, which included $23 million at Consumers. These amounts were recorded in other non ‑current assets on the consolidated balance sheets, but will be included in the long-term debt balances under this 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 in vestments 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. During the year ended December 31, 20 15, CMS Energy recorded a $3 million unrealized net loss on equity investments in AOCI and Consumers recorded a $1 million unrealized net loss on equity investments in AOCI. 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. CMS Energy and Consumers are evaluating whether there may be further impacts 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 2015 ‑13, Application of the Normal Purchases and Normal Sales Scope Exception to Certain Electricity Contracts within Nodal Energy Markets: This standard, which became effective in August 2015 for CMS Energy and Consumers, was intended to resolve diversity in practice regarding whether certain electricity contracts are eligible for the normal purchases and sales scope exception from derivative accounting. The standard clarifies that contracts that require transmission of electricity through a market with established price points at each node or hub location are eligible for the scope exception. Consumers applies the normal purchases and sales scope exception to many PPAs that require transmission of electricity through the MISO market, which has price points at various node or hub locations. Since this standard clarifies that these contracts are eligible for the scope exception, which is consistent with Consumers’ treatment, the standard had no impact on CMS Energy’s or Consumers’ consolidated financial statements. ASU 2015 ‑17, Balance Sheet Classification of Deferred Taxes: This standard eliminates the requirement to separate deferred income tax assets and liabilities into current and non ‑ current amounts on a classified balance sheet. Under the standard, all deferred income tax amounts should be classified as non ‑ current. The standard will be effective on January 1, 2017 for CMS Energy and Consumers, but early adoption is permitted. The standard can be applied either prospectively or retrospectively. CMS Energy and Consumers elected to adopt the standard early for the year ended Decemb er 31, 2015 and applied the standard retrospectively to all prior periods. Accordingly, CMS Energy reclassified $66 million of current deferred income tax liabilities to non ‑current deferred income tax li abilities at December 31, 2014, and Consumers reclassified $80 million of current deferred income tax liabilities to non ‑ current deferred income tax liabilities at December 31, 2014. New Accounting Standards Not Yet Effective ASU 2014 ‑09, Revenue from Contracts with Customers: This standard, which will become effective January 1, 2018 for CMS Energy and Consumers, 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. Entities will have the option to apply the standard retrospectively to all prior periods presented, or to apply it retrospectively only to contracts existing at the effective date, with the cumulative effect of the standard recorded as an adjustment to beginning retained earnings. CMS Energy and Consumers are evaluating the impact of the standard on their consolidated financial statements. 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, effective 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 intended 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 apply to awards of this type. Therefore, CMS Energy and Consumers do not expect the standard to impact their consolidated financial statements. ASU 2015 ‑02, Amendments to the Consolidation Analysis: This standard, effective 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 have assessed this standard and do not expect that it will result in any changes to their consolidation conclusions or have any impact on their consolidated income, cash flows, or financial position. ASU 2015 ‑03, Simplifying the Presentation of Debt Issuance Costs: This standard, effective 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. Presently, debt issuance costs are reported as an asset. The new guidance aligns the presentation of debt issuance costs with debt discounts and premiums. The standard is to be applied retrospectively to all prior periods presented. At December 31, 2015 , CMS Energy had $41 million of unamortized debt issuance costs, which included $23 million at Consumers. These amounts were recorded in other non ‑current assets on the consolidated balance sheets, but will be included in the long-term debt balances under this 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 in vestments 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. During the year ended December 31, 20 15, CMS Energy recorded a $3 million unrealized net loss on equity investments in AOCI and Consumers recorded a $1 million unrealized net loss on equity investments in AOCI. 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. CMS Energy and Consumers are evaluating whether there may be further impacts of the standard on their consolidated financial statements.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2015
Regulatory Matters	3: R egulatory M atters 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 allocation among 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 2015 2014 Regulatory assets Current Energy optimization plan incentive 1 2016 $ 16 $ 17 Securitized costs – electric utility restructuring legislation 2 2015 - 61 Major maintenance 2 2015 - 8 Other 2015 - 3 Total current regulatory assets $ 16 $ 89 Non-current Postretirement benefits 3 various $ 1,096 $ 1,195 Securitized costs – electric generating units to be retired 2 2029 348 370 ARO 4 various 151 139 MGP sites 4 various 146 147 Unamortized debt costs 4 various 61 66 Gas storage inventory adjustments 4 various 18 21 Energy optimization plan incentive 1 2017 18 17 Other various 2 1 Total non ‑current regulatory assets $ 1,840 $ 1,956 Total regulatory assets $ 1,856 $ 2,045 Regulatory liabilities Current Income taxes, net 2016 $ 64 $ 64 Securitized costs – electric utility restructuring legislation 2016 14 - Other 2016 4 3 Total current regulatory liabilities $ 82 $ 67 Non-current Cost of removal various $ 1,745 $ 1,673 Renewable energy plan 2028 109 131 ARO various 73 83 Income taxes, net various 64 103 Renewable energy grant 2043 60 63 Energy optimization plan various 26 32 Other various 11 10 Total non ‑current regulatory liabilities $ 2,088 $ 2,095 Total regulatory liabilities $ 2,170 $ 2,162 1 These regulatory assets have arisen from alternative revenue programs and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return. 2 These regulatory assets are included in rate base (or are expected to be included, for costs incurred subsequent to the most recently approved rate case), thereby providing a return on expenditures, or provide a specific return on investment authorized by the MPSC. 3 This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return. 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 May 2015, Consumers filed its annual report and reconciliation for its energy optimization plan, requesting approval of its energy optimization plan costs for 2014. In September 2015, the MPSC approved a settlement agreement authorizing Consumers to collect $ 17 million from customers during 2016 as an incentive payment for exceeding statutory targets under both its gas and electric energy optimization plans during 2014. Consumers also exceeded its statutory savings targets in 2015, 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 2016. Securitized Costs – Electric Utility Restructuring Legislation: In 2000, the MPSC authorized Consumers to securitize certain qualified costs incurred as a result of electric utility restructuring legislation. Consumers amortized this regulatory asset over the life of the related Securitization bonds, which were paid in full in October 2015. During 2015, Consumers overcollected surcharges related to this Securitization and, as a result, recorded a regulatory liability. Consumers filed a reconciliation with the MPSC in January 2016, requesting to refund this amount to customers in 2016. Major Maintenance: In its 2012 order in Consumers’ electric rate case, the MPSC allowed Consumers to defer major maintenance costs associated with its electric generating units in excess of the costs approved in the rate order and to recover those excess costs from customers, subject to MPSC approval. In November 2014, the MPSC approved a settlement agreement authorizing Consumers to recover $ 10 million of such excess costs over a six -month period that ended in May 2015. 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 – Electric Generating Units to be Retired: 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 plans to retire by 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 July 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 Debt Costs: Under regulatory accounting, any unamortized debt costs related to debt redeemed with the proceeds of new debt are 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 2015 , Consumers returned $64 million of income tax benefits to customers. 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 the renewable portfolio standards prescribed by the 2008 Energy Law 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, 2015 and 2014 , 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 Electric Rate Case: In December 2014, Consumers filed an application with the MPSC seeking an annual rate increase of $163 million, based on a 10.7 percent authorized return on equity. 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 planned retirement of seven coal -fueled electric generating units, the annual rate increase will be reduced by $39 million to $126 million. In June 2015, Consumers self-implemented an annual rate increase of $110 million, subject to refund with interest. Consumers does not expect that a significant refund of self-implemented rates will be required. Electric Rate Design: In June 2015, the MPSC issued an order on Consumers’ proposal for a new electric rate design, authorizing a reallocation of annual costs among customer classes. This new allocation will better ensure that rates reflect the cost of service for each customer class and will have the effect of making rates for energy-intensive industrial customers more competitive, while keeping residential bills below the national average. In Dec ember 2015, the new rate design went into effect. Depreciation Rate Case: In June 2014, Consumers filed a depreciation case related to its electric and common utility property. In this case, Consumers requested an increase in depreciation expense, and its recovery of that expense, of $28 million annually. In May 2015, the MPSC approved a settlement agreement authorizing an increase in Consumers’ depreciation expense, and its recovery of that expense, of $6 million annually based on December 31, 2013 balances. In Dec ember 2015, the new depreciation rates went into effect. Consumers Gas Utility Gas Rate Case: In July 2014, Consumers filed an application with the MPSC seeking an annual rate increase of $88 million. The filing requested authority to recover new investments that will allow Consumers to improve system reliability, comply with regulations, and enhance technology. In January 2015, the MPSC approved a settlement agreement authorizing a $45 million annual rate increase, based on a 10.3 percent authorized return on equity. This was Consumers’ first gas base rate increase since 2012. 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 and are included in accrued gas revenue on Consumers’ consolidated balance sheets. Overrecoveries represent previously collected revenues that will be refunded to customers and are included in accrued rate refunds on Consumers’ consolidated balance sheets. Presented in the following table are the assets and liabilities for PSCR and GCR underrecoveries and overrecoveries reflected on Consumers’ consolidated balance sheets: In Millions December 31 2015 2014 Assets Accrued gas revenue $ - $ 27 Liabilities Accrued rate refunds 26 6 PSCR Plans and Reconciliations: In May 2015, the MPSC issued an order in Consumers’ 2013 PSCR plan, authorizing the 2013 PSCR factor that Consumers self-implemented beginning in January 2013. Consumers filed its 2013 PSCR reconciliation in March 2014, requesting full recovery of $1.9 billion of power costs and authorization to roll into its 2014 PSCR plan the overrecovery of $10 million. Consumers submitted its 2014 PSCR plan to the MPSC in September 2013 and, in accordance with its proposed plan, self-implemented the 2014 PSCR factor beginning in January 2014. Consumers’ power supply costs for 2014 were significantly higher than those projected in its 2014 PSCR plan due to severe winter weather during the three months ended March 31, 2014, as extreme cold weather and heavy snowfall inhibited the delivery and use of coal at Consumers’ coal-fueled generating units. Additionally, increases in natural gas prices raised the cost of electricity purchased from the MISO energy market as well as the cost of power generated at Consumers’ natural gas-fueled generating units. Consumers filed an amendment to its 2014 PSCR plan in March 2014, requesting approval to increase the 2014 PSCR factor. Consumers self-implemented the revised factor in July 2014. In March 2015, Consumers filed its 2014 PSCR reconciliation, requesting full recovery of $2.1 billion of power costs and authorization to roll into its 2015 PSCR plan the overrecovery of $6 million. Consumers submitted its 2015 PSCR plan to the MPSC in September 2014 and, in accordance with its proposed plan, self-implemented the 2015 PSCR factor beginning in January 2015. Consumers had a n $8 million PSCR ov errecovery at December 31, 2015 . GCR Plans and Reconciliations: In July 2014, the MPSC issued an order in Consumers’ 2013-2014 GCR plan, authorizing the 2013-2014 GCR factor that Consumers self-implemented beginning in April 2013. Due to the impact on natural gas prices of extended periods of colder-than-normal winter weather in Michigan and throughout the United States during the three months ended March 31, 2014, Consumers’ natural gas fuel costs for this period were significantly higher than those projected in its 2013-2014 GCR plan. As a result, Consumers calculated an $84 million underrecovery for the 2013-2014 GCR plan year. In the reconciliation it filed in June 2014, Consumers requested full recovery of $0.9 billion of gas costs and authorization to roll into its 2014-2015 GCR plan the underrecovery of $84 million. In June 2015, the MPSC issued an order in Consumers’ 2014-2015 GCR plan, authorizing the 2014-2015 GCR factor that Consumers self-implemented beginning in April 2014. Consumers filed its 2014-2015 GCR reconciliation in June 2015, requesting full recovery of $0.8 billion of gas costs and authorization to roll into its 2015-2016 GCR plan the overrecovery of $9 million. Consumers submitted its 2015-2016 GCR plan to the MPSC in December 2014 and, in accordance with its proposed plan, self-implemented the 2015-2016 GCR charge beginning in April 2015. Consumers had a n $18 million GCR overrecovery recorded at December 31, 2015 .
Consumers Energy Company [Member]
Regulatory Matters	3: R egulatory M atters 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 allocation among 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 2015 2014 Regulatory assets Current Energy optimization plan incentive 1 2016 $ 16 $ 17 Securitized costs – electric utility restructuring legislation 2 2015 - 61 Major maintenance 2 2015 - 8 Other 2015 - 3 Total current regulatory assets $ 16 $ 89 Non-current Postretirement benefits 3 various $ 1,096 $ 1,195 Securitized costs – electric generating units to be retired 2 2029 348 370 ARO 4 various 151 139 MGP sites 4 various 146 147 Unamortized debt costs 4 various 61 66 Gas storage inventory adjustments 4 various 18 21 Energy optimization plan incentive 1 2017 18 17 Other various 2 1 Total non ‑current regulatory assets $ 1,840 $ 1,956 Total regulatory assets $ 1,856 $ 2,045 Regulatory liabilities Current Income taxes, net 2016 $ 64 $ 64 Securitized costs – electric utility restructuring legislation 2016 14 - Other 2016 4 3 Total current regulatory liabilities $ 82 $ 67 Non-current Cost of removal various $ 1,745 $ 1,673 Renewable energy plan 2028 109 131 ARO various 73 83 Income taxes, net various 64 103 Renewable energy grant 2043 60 63 Energy optimization plan various 26 32 Other various 11 10 Total non ‑current regulatory liabilities $ 2,088 $ 2,095 Total regulatory liabilities $ 2,170 $ 2,162 1 These regulatory assets have arisen from alternative revenue programs and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return. 2 These regulatory assets are included in rate base (or are expected to be included, for costs incurred subsequent to the most recently approved rate case), thereby providing a return on expenditures, or provide a specific return on investment authorized by the MPSC. 3 This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return. 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 May 2015, Consumers filed its annual report and reconciliation for its energy optimization plan, requesting approval of its energy optimization plan costs for 2014. In September 2015, the MPSC approved a settlement agreement authorizing Consumers to collect $ 17 million from customers during 2016 as an incentive payment for exceeding statutory targets under both its gas and electric energy optimization plans during 2014. Consumers also exceeded its statutory savings targets in 2015, 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 2016. Securitized Costs – Electric Utility Restructuring Legislation: In 2000, the MPSC authorized Consumers to securitize certain qualified costs incurred as a result of electric utility restructuring legislation. Consumers amortized this regulatory asset over the life of the related Securitization bonds, which were paid in full in October 2015. During 2015, Consumers overcollected surcharges related to this Securitization and, as a result, recorded a regulatory liability. Consumers filed a reconciliation with the MPSC in January 2016, requesting to refund this amount to customers in 2016. Major Maintenance: In its 2012 order in Consumers’ electric rate case, the MPSC allowed Consumers to defer major maintenance costs associated with its electric generating units in excess of the costs approved in the rate order and to recover those excess costs from customers, subject to MPSC approval. In November 2014, the MPSC approved a settlement agreement authorizing Consumers to recover $ 10 million of such excess costs over a six -month period that ended in May 2015. 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 – Electric Generating Units to be Retired: 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 plans to retire by 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 July 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 Debt Costs: Under regulatory accounting, any unamortized debt costs related to debt redeemed with the proceeds of new debt are 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 2015 , Consumers returned $64 million of income tax benefits to customers. 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 the renewable portfolio standards prescribed by the 2008 Energy Law 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, 2015 and 2014 , 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 Electric Rate Case: In December 2014, Consumers filed an application with the MPSC seeking an annual rate increase of $163 million, based on a 10.7 percent authorized return on equity. 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 planned retirement of seven coal -fueled electric generating units, the annual rate increase will be reduced by $39 million to $126 million. In June 2015, Consumers self-implemented an annual rate increase of $110 million, subject to refund with interest. Consumers does not expect that a significant refund of self-implemented rates will be required. Electric Rate Design: In June 2015, the MPSC issued an order on Consumers’ proposal for a new electric rate design, authorizing a reallocation of annual costs among customer classes. This new allocation will better ensure that rates reflect the cost of service for each customer class and will have the effect of making rates for energy-intensive industrial customers more competitive, while keeping residential bills below the national average. In Dec ember 2015, the new rate design went into effect. Depreciation Rate Case: In June 2014, Consumers filed a depreciation case related to its electric and common utility property. In this case, Consumers requested an increase in depreciation expense, and its recovery of that expense, of $28 million annually. In May 2015, the MPSC approved a settlement agreement authorizing an increase in Consumers’ depreciation expense, and its recovery of that expense, of $6 million annually based on December 31, 2013 balances. In Dec ember 2015, the new depreciation rates went into effect. Consumers Gas Utility Gas Rate Case: In July 2014, Consumers filed an application with the MPSC seeking an annual rate increase of $88 million. The filing requested authority to recover new investments that will allow Consumers to improve system reliability, comply with regulations, and enhance technology. In January 2015, the MPSC approved a settlement agreement authorizing a $45 million annual rate increase, based on a 10.3 percent authorized return on equity. This was Consumers’ first gas base rate increase since 2012. 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 and are included in accrued gas revenue on Consumers’ consolidated balance sheets. Overrecoveries represent previously collected revenues that will be refunded to customers and are included in accrued rate refunds on Consumers’ consolidated balance sheets. Presented in the following table are the assets and liabilities for PSCR and GCR underrecoveries and overrecoveries reflected on Consumers’ consolidated balance sheets: In Millions December 31 2015 2014 Assets Accrued gas revenue $ - $ 27 Liabilities Accrued rate refunds 26 6 PSCR Plans and Reconciliations: In May 2015, the MPSC issued an order in Consumers’ 2013 PSCR plan, authorizing the 2013 PSCR factor that Consumers self-implemented beginning in January 2013. Consumers filed its 2013 PSCR reconciliation in March 2014, requesting full recovery of $1.9 billion of power costs and authorization to roll into its 2014 PSCR plan the overrecovery of $10 million. Consumers submitted its 2014 PSCR plan to the MPSC in September 2013 and, in accordance with its proposed plan, self-implemented the 2014 PSCR factor beginning in January 2014. Consumers’ power supply costs for 2014 were significantly higher than those projected in its 2014 PSCR plan due to severe winter weather during the three months ended March 31, 2014, as extreme cold weather and heavy snowfall inhibited the delivery and use of coal at Consumers’ coal-fueled generating units. Additionally, increases in natural gas prices raised the cost of electricity purchased from the MISO energy market as well as the cost of power generated at Consumers’ natural gas-fueled generating units. Consumers filed an amendment to its 2014 PSCR plan in March 2014, requesting approval to increase the 2014 PSCR factor. Consumers self-implemented the revised factor in July 2014. In March 2015, Consumers filed its 2014 PSCR reconciliation, requesting full recovery of $2.1 billion of power costs and authorization to roll into its 2015 PSCR plan the overrecovery of $6 million. Consumers submitted its 2015 PSCR plan to the MPSC in September 2014 and, in accordance with its proposed plan, self-implemented the 2015 PSCR factor beginning in January 2015. Consumers had a n $8 million PSCR ov errecovery at December 31, 2015 . GCR Plans and Reconciliations: In July 2014, the MPSC issued an order in Consumers’ 2013-2014 GCR plan, authorizing the 2013-2014 GCR factor that Consumers self-implemented beginning in April 2013. Due to the impact on natural gas prices of extended periods of colder-than-normal winter weather in Michigan and throughout the United States during the three months ended March 31, 2014, Consumers’ natural gas fuel costs for this period were significantly higher than those projected in its 2013-2014 GCR plan. As a result, Consumers calculated an $84 million underrecovery for the 2013-2014 GCR plan year. In the reconciliation it filed in June 2014, Consumers requested full recovery of $0.9 billion of gas costs and authorization to roll into its 2014-2015 GCR plan the underrecovery of $84 million. In June 2015, the MPSC issued an order in Consumers’ 2014-2015 GCR plan, authorizing the 2014-2015 GCR factor that Consumers self-implemented beginning in April 2014. Consumers filed its 2014-2015 GCR reconciliation in June 2015, requesting full recovery of $0.8 billion of gas costs and authorization to roll into its 2015-2016 GCR plan the overrecovery of $9 million. Consumers submitted its 2015-2016 GCR plan to the MPSC in December 2014 and, in accordance with its proposed plan, self-implemented the 2015-2016 GCR charge beginning in April 2015. Consumers had a n $18 million GCR overrecovery recorded at December 31, 2015 .

Contingencies And Commitments

Contingencies And Commitments	12 Months Ended
	Dec. 31, 2015
Contingencies And Commitments	4: C ontingencies and C ommitments 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 remain 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 putative class period, January 1, 2000 through October 31, 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 1, 2000 and October 31, 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. The plaintiffs did not appeal the dismissal of CMS Energy as a defendant in these cases, but other CMS Energy entities remain as defendants. 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 have been remanded back to the federal district court. 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. CMS Land is presently working with the MDEQ to renew this permit, which requires renewal every five years. Until a new permit is issued, CMS Land is authorized to continue operating under the existing permit. 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, 2015 , CMS Energy had a recorded liability of $ 58 million for its remaining obligations. 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 $ 74 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 2016 2017 2018 2019 2020 CMS Energy Long-term liquid disposal and operating and maintenance costs $ 6 $ 5 $ 5 $ 5 $ 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 $ 5 million. At December 31, 2015 , Consumers had a recorded liability of $ 3 million, the minimum amount in the range of its estimated probable NREPA liability. 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 of potentially responsible parties involved with each site, affect Consumers’ share of the total liability. At December 31, 2015 , 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. 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. Consumers cannot predict the financial impact or outcome of this matter. CCRs: In April 2015, the EPA published a final rule regulating CCRs, such as coal ash, under the Resource Conservation and Recovery Act. In September 2015, the MDEQ submitted a draft plan to the EPA in which it declared its intent to explicitly regulate these facilities under state laws, and the EPA responded, confirming that it agreed with the MDEQ’s regulatory approach. Accordingly, Consumers recorded a $68 million increase to its coal ash disposal ARO liability and a corresponding increase to plant, property, and equipment that will be amortized over the remaining lives of the facilities. For additional details on the ARO liability, see Note 11, Asset Retirement Obligations. 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, 2015 , Consumers had a recorded liability of $ 114 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 $ 129 million. Consumers expects to pay the following amounts for remediation and other response activity costs in each of the next five years: In Millions 2016 2017 2018 2019 2020 Consumers Remediation and other response activity costs $ 14 $ 19 $ 11 $ 14 $ 19 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. At one of the MGP sites, Consumers is waiting for a local agency to make certain decisions on work being carried out adjacent to the site. Depending on the outcome, the agency ’ s decisions could impact Consumers ’ remediation strategy and result in an increase in its cost estimates in 2016. 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, 2015 , Consumers had a regulatory asset of $146 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, 2015 , Consumers had a recorded liability of less than $1 million, the minimum amount in the range of its estimated probable liability. Guarantees Presented in the following table are CMS Energy’s and Consumers’ guarantees at December 31, 2015 : 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 $ 143 $ 7 Guarantees 2 Various Indefinite 51 - Consumers Guarantee 2 July 2011 Indefinite $ 30 $ - 1 The se 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 DOE in connection with a settlement agreement regarding damages resulting from the DOE’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 DOE and CMS Energy’s 1994 guarantee of non-recourse revenue bonds issued by Genesee. For additional details on this guarantee, see Note 19, Variable Interest Entities. Additionally, in the normal course of business, CMS Energy, Consumers, and certain other subsidiaries of CMS Energy have enter ed into various agreements containing tax and other indemnity provisions for which they are unable to estimate the maximum potential obligation. The current carrying value of these indemnity obligations is less than $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 to December 2004. It determined that Consumers’ electric and natural gas distribution equipment was not eligible for an industrial-processing exemption and therefore was 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 has continued to apply the industrial-processing exemption for the years subsequent to 2004. In December 2015, Consumers and the Michigan Department of Treasury reached a settlement agreement under which the Michigan Department of Treasury will refund to Consumers the majority of use tax that Consumers paid on electric distribution equipment for the period from October 1997 through December 2004. Accordin gly, Consumers will receive $37 million, which comprises a $19 million refund of taxes paid, a $12 million refund of interest paid, and $6 million of interest owed to Consumers. In December 2015, Consumers recorded a $12 million reduction in other interest expense and $6 million in interest income. The taxes paid were originally capitalized as a cost of the equipment. Therefore, Consumers recorded the $19 million tax refund as a reduction in plant, property, and equipment. Consumers also recorded an additional $5 million reduction in g eneral t axes for the elimination of a loss contingency previously recorded for this matter. The parties further agreed to continue to meet to reach agreement on a reasonable method of apportionment relating to Consumer s ’ natural gas system for the period from October 1997 to December 2004 and to Consumers’ electric and natural gas distribution equipment for the period from January 2005 to December 2014. 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, 2015 for each of the periods shown: In Millions Payments Due Total 2016 2017 2018 2019 2020 Beyond 2020 CMS Energy, including Consumers Total PPAs $ 9,947 $ 999 $ 1,027 $ 969 $ 1,003 $ 995 $ 4,954 Other 2,200 904 580 251 111 63 291 Consumers PPAs MCV PPA $ 3,003 $ 335 $ 345 $ 277 $ 321 $ 296 $ 1,429 Palisades PPA 2,327 342 352 363 374 387 509 Related party PPAs 977 82 82 82 85 87 559 Other PPAs 3,640 240 248 247 223 225 2,457 Total PPAs $ 9,947 $ 999 $ 1,027 $ 969 $ 1,003 $ 995 $ 4,954 Other 1,908 870 551 224 83 34 146 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 admi nistrative and general expenses · a variable energy charge based on the MCV Partnership’s cost of producti on 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 t he MCV PPA’s term in March 2025 Capacity and energy charges under the MCV PPA were $ 282 million in 2015 , $ 300 million in 2014 , and $ 278 million in 2013 . Palisades PPA: Consumers has a PPA expiring in 2022 with Entergy to purchase 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 $ 352 million in 2015 , $ 302 million in 2014 , and $ 338 million in 2013 . For further details about Palisades, see Note 10, Leases. Other PPAs: Consumers has PPAs expiring between 201 6 and 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 $347 million in 2015 , $354 million in 2014 , and $345 million in 2013 .
Consumers Energy Company [Member]
Contingencies And Commitments	4: C ontingencies and C ommitments 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 remain 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 putative class period, January 1, 2000 through October 31, 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 1, 2000 and October 31, 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. The plaintiffs did not appeal the dismissal of CMS Energy as a defendant in these cases, but other CMS Energy entities remain as defendants. 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 have been remanded back to the federal district court. 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. CMS Land is presently working with the MDEQ to renew this permit, which requires renewal every five years. Until a new permit is issued, CMS Land is authorized to continue operating under the existing permit. 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, 2015 , CMS Energy had a recorded liability of $ 58 million for its remaining obligations. 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 $ 74 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 2016 2017 2018 2019 2020 CMS Energy Long-term liquid disposal and operating and maintenance costs $ 6 $ 5 $ 5 $ 5 $ 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 $ 5 million. At December 31, 2015 , Consumers had a recorded liability of $ 3 million, the minimum amount in the range of its estimated probable NREPA liability. 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 of potentially responsible parties involved with each site, affect Consumers’ share of the total liability. At December 31, 2015 , 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. 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. Consumers cannot predict the financial impact or outcome of this matter. CCRs: In April 2015, the EPA published a final rule regulating CCRs, such as coal ash, under the Resource Conservation and Recovery Act. In September 2015, the MDEQ submitted a draft plan to the EPA in which it declared its intent to explicitly regulate these facilities under state laws, and the EPA responded, confirming that it agreed with the MDEQ’s regulatory approach. Accordingly, Consumers recorded a $68 million increase to its coal ash disposal ARO liability and a corresponding increase to plant, property, and equipment that will be amortized over the remaining lives of the facilities. For additional details on the ARO liability, see Note 11, Asset Retirement Obligations. 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, 2015 , Consumers had a recorded liability of $ 114 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 $ 129 million. Consumers expects to pay the following amounts for remediation and other response activity costs in each of the next five years: In Millions 2016 2017 2018 2019 2020 Consumers Remediation and other response activity costs $ 14 $ 19 $ 11 $ 14 $ 19 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. At one of the MGP sites, Consumers is waiting for a local agency to make certain decisions on work being carried out adjacent to the site. Depending on the outcome, the agency ’ s decisions could impact Consumers ’ remediation strategy and result in an increase in its cost estimates in 2016. 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, 2015 , Consumers had a regulatory asset of $146 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, 2015 , Consumers had a recorded liability of less than $1 million, the minimum amount in the range of its estimated probable liability. Guarantees Presented in the following table are CMS Energy’s and Consumers’ guarantees at December 31, 2015 : 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 $ 143 $ 7 Guarantees 2 Various Indefinite 51 - Consumers Guarantee 2 July 2011 Indefinite $ 30 $ - 1 The se 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 DOE in connection with a settlement agreement regarding damages resulting from the DOE’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 DOE and CMS Energy’s 1994 guarantee of non-recourse revenue bonds issued by Genesee. For additional details on this guarantee, see Note 19, Variable Interest Entities. Additionally, in the normal course of business, CMS Energy, Consumers, and certain other subsidiaries of CMS Energy have enter ed into various agreements containing tax and other indemnity provisions for which they are unable to estimate the maximum potential obligation. The current carrying value of these indemnity obligations is less than $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 to December 2004. It determined that Consumers’ electric and natural gas distribution equipment was not eligible for an industrial-processing exemption and therefore was 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 has continued to apply the industrial-processing exemption for the years subsequent to 2004. In December 2015, Consumers and the Michigan Department of Treasury reached a settlement agreement under which the Michigan Department of Treasury will refund to Consumers the majority of use tax that Consumers paid on electric distribution equipment for the period from October 1997 through December 2004. Accordin gly, Consumers will receive $37 million, which comprises a $19 million refund of taxes paid, a $12 million refund of interest paid, and $6 million of interest owed to Consumers. In December 2015, Consumers recorded a $12 million reduction in other interest expense and $6 million in interest income. The taxes paid were originally capitalized as a cost of the equipment. Therefore, Consumers recorded the $19 million tax refund as a reduction in plant, property, and equipment. Consumers also recorded an additional $5 million reduction in g eneral t axes for the elimination of a loss contingency previously recorded for this matter. The parties further agreed to continue to meet to reach agreement on a reasonable method of apportionment relating to Consumer s ’ natural gas system for the period from October 1997 to December 2004 and to Consumers’ electric and natural gas distribution equipment for the period from January 2005 to December 2014. 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, 2015 for each of the periods shown: In Millions Payments Due Total 2016 2017 2018 2019 2020 Beyond 2020 CMS Energy, including Consumers Total PPAs $ 9,947 $ 999 $ 1,027 $ 969 $ 1,003 $ 995 $ 4,954 Other 2,200 904 580 251 111 63 291 Consumers PPAs MCV PPA $ 3,003 $ 335 $ 345 $ 277 $ 321 $ 296 $ 1,429 Palisades PPA 2,327 342 352 363 374 387 509 Related party PPAs 977 82 82 82 85 87 559 Other PPAs 3,640 240 248 247 223 225 2,457 Total PPAs $ 9,947 $ 999 $ 1,027 $ 969 $ 1,003 $ 995 $ 4,954 Other 1,908 870 551 224 83 34 146 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 admi nistrative and general expenses · a variable energy charge based on the MCV Partnership’s cost of producti on 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 t he MCV PPA’s term in March 2025 Capacity and energy charges under the MCV PPA were $ 282 million in 2015 , $ 300 million in 2014 , and $ 278 million in 2013 . Palisades PPA: Consumers has a PPA expiring in 2022 with Entergy to purchase 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 $ 352 million in 2015 , $ 302 million in 2014 , and $ 338 million in 2013 . For further details about Palisades, see Note 10, Leases. Other PPAs: Consumers has PPAs expiring between 201 6 and 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 $347 million in 2015 , $354 million in 2014 , and $345 million in 2013 .

Financings And Capitalization

Financings And Capitalization	12 Months Ended
	Dec. 31, 2015
Financings And Capitalization	5: F inancings and C apitalization Presented in the following table is CMS Energy’s long-term debt at December 31 : In Millions Interest Rate (%) Maturity 2015 2014 CMS Energy parent Senior notes 6.550 2017 $ 250 $ 250 5.050 2018 250 250 8.750 2019 300 300 6.250 2020 300 300 5.050 2022 300 300 3.875 2024 250 250 3.600 2025 250 - 4.700 2043 250 250 4.875 2044 300 300 Total CMS Energy senior notes $ 2,450 $ 2,200 Term loan facility variable 1 2017 180 180 Total CMS Energy parent $ 2,630 $ 2,380 Consumers $ 5,409 $ 5,283 Other CMS Energy subsidiaries EnerBank certificates of deposit 1.365 2 2016 -2025 $ 1,098 $ 884 Total other CMS Energy subsidiaries $ 1,098 $ 884 Total CMS Energy principal amount outstanding $ 9,137 $ 8,547 Current amounts (684) (519) Net unamortized discounts (12) (12) Total CMS Energy long-term debt $ 8,441 $ 8,016 1 Outstanding borrowings bear interest at an annual interest rate of LIBOR plus 0.85 percent ( 1.19 percent at December 31, 2015 ). 2 The weighted-average interest rate for EnerBank’s certificates of deposit was 1.36 percent at December 31, 2015 and 1. 22 percent at December 31, 2014 . 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 2015 2014 Consumers FMBs 1 2.600 2015 $ - $ 50 5.500 2016 173 173 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 - 4.350 2064 250 250 $ 4,773 $ 4,573 Securitization bonds 5.760 2015 - 49 2.689 2 2020-2029 3 353 378 $ 353 $ 427 Senior notes 6.875 2018 180 180 Tax-exempt pollution control revenue bonds various 2018-2035 103 103 Total Consumers principal amount outstanding $ 5,409 $ 5,283 Current amounts (198) (124) Net unamortized discounts (5) (5) Total Consumers long-term debt $ 5,206 $ 5,154 1 The weighted-average interest rate for Consumers’ FMBs was 4.73 percent at December 31, 2015 and 4.75 percent at December 31, 2014 . 2 The weighted-average interest rate for Consumers’ Securitization bonds issued through its subsidiary Consumers 2014 Securitization Funding was 2.69 percent at December 31, 2015 and 2.60 percent at December 31, 2014 . 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, 2015 : Principal Issue/Retirement (In Millions) Interest Rate Date Maturity Date Debt issuances CMS Energy parent Senior notes $ 250 3.600 % November 2015 November 2025 Total CMS Energy parent $ 250 Consumers FMBs $ 250 4.100 % November 2015 November 2045 Total Consumers $ 250 Total CMS Energy $ 500 Debt retirements Consumers FMBs $ 50 2.600 % October 2015 October 2015 Total Consumers $ 50 Total CMS Energy $ 50 FMBs: Consumers secures its FMBs by a mortgage and lien on substantially all of its property. Consumers’ ability to issue FMBs 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. Regulatory Authorization for Financings: Consumers is required to maintain FERC authorization for financings. In June 2014, 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, 2015 , Consumers had entered into short-term borrowing programs allowing it to issue up to $800 milli on in short-term securities; $249 million of securities were outstanding under these programs. FERC has also authorized Consumers to issue and sell up to $ 1.9 billion of secured and unsecured long-term securities for general corporate purposes. The remaining availability was $ 900 million at December 31, 2015 . The authorizations were effective July 1, 2014 and terminate June 30, 2016. 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, 2015 , the aggregate annual contractual maturities for long-term debt for the next five years were: In Millions 2016 2017 2018 2019 2020 CMS Energy, including Consumers Long-term debt $ 684 $ 1,010 $ 911 $ 1,288 $ 801 Consumers Long-term debt $ 198 $ 375 $ 523 $ 876 $ 426 Revolving Credit Facilities: The following secured revolving credit facilities with banks were available at December 31, 2015 : In Millions Amount of Amount Letters of Credit Amount Expiration Date Facility Borrowed Outstanding Available CMS Energy parent May 27, 2020 1 $ 550 $ - $ 1 $ 549 Consumers May 27, 2020 2 $ 650 $ - $ 9 $ 641 November 23, 2017 2,3 250 - - 250 May 9, 2018 2 30 - 30 - 1 Obligations under this facility are secured by Consumers common stock . 2 Obligations under this facility are secured by FMBs of Consumers. 3 In November 2015, Consumers entered into a new $250 million credit facility and terminated its $250 million accounts receivable sales program. 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 would not issue commercial paper in an amount exceeding the available revolver capacity. At December 31, 2015 , $ 249 million of commercial paper notes with a weighted - average annual interest rate of 0. 91 percent w as outstanding under this program. Dividend Restrictions: At December 31, 2015 , payment of dividends by CMS Energy on its common stock was limited to $ 3.9 billion under provisions of the Michigan Business Corporation Act of 1972 . Under the provisions of its articles of incorporation, at December 31, 2015 , Consumers had $ 884 million 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, 2015 , Consumers paid $ 474 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. In 2015, CMS Energy issued 888,610 shares of common stock at an average price of $33.76 per share, resulting in net proceeds of $30 million. 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 2015 2014 Cumulative, $100 par value, authorized 7,500,000 shares, with no mandatory redemption $ 4.50 $ 110.00 373,148 $ 37 $ 37
Consumers Energy Company [Member]
Financings And Capitalization	5: F inancings and C apitalization Presented in the following table is CMS Energy’s long-term debt at December 31 : In Millions Interest Rate (%) Maturity 2015 2014 CMS Energy parent Senior notes 6.550 2017 $ 250 $ 250 5.050 2018 250 250 8.750 2019 300 300 6.250 2020 300 300 5.050 2022 300 300 3.875 2024 250 250 3.600 2025 250 - 4.700 2043 250 250 4.875 2044 300 300 Total CMS Energy senior notes $ 2,450 $ 2,200 Term loan facility variable 1 2017 180 180 Total CMS Energy parent $ 2,630 $ 2,380 Consumers $ 5,409 $ 5,283 Other CMS Energy subsidiaries EnerBank certificates of deposit 1.365 2 2016 -2025 $ 1,098 $ 884 Total other CMS Energy subsidiaries $ 1,098 $ 884 Total CMS Energy principal amount outstanding $ 9,137 $ 8,547 Current amounts (684) (519) Net unamortized discounts (12) (12) Total CMS Energy long-term debt $ 8,441 $ 8,016 1 Outstanding borrowings bear interest at an annual interest rate of LIBOR plus 0.85 percent ( 1.19 percent at December 31, 2015 ). 2 The weighted-average interest rate for EnerBank’s certificates of deposit was 1.36 percent at December 31, 2015 and 1. 22 percent at December 31, 2014 . 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 2015 2014 Consumers FMBs 1 2.600 2015 $ - $ 50 5.500 2016 173 173 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 - 4.350 2064 250 250 $ 4,773 $ 4,573 Securitization bonds 5.760 2015 - 49 2.689 2 2020-2029 3 353 378 $ 353 $ 427 Senior notes 6.875 2018 180 180 Tax-exempt pollution control revenue bonds various 2018-2035 103 103 Total Consumers principal amount outstanding $ 5,409 $ 5,283 Current amounts (198) (124) Net unamortized discounts (5) (5) Total Consumers long-term debt $ 5,206 $ 5,154 1 The weighted-average interest rate for Consumers’ FMBs was 4.73 percent at December 31, 2015 and 4.75 percent at December 31, 2014 . 2 The weighted-average interest rate for Consumers’ Securitization bonds issued through its subsidiary Consumers 2014 Securitization Funding was 2.69 percent at December 31, 2015 and 2.60 percent at December 31, 2014 . 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, 2015 : Principal Issue/Retirement (In Millions) Interest Rate Date Maturity Date Debt issuances CMS Energy parent Senior notes $ 250 3.600 % November 2015 November 2025 Total CMS Energy parent $ 250 Consumers FMBs $ 250 4.100 % November 2015 November 2045 Total Consumers $ 250 Total CMS Energy $ 500 Debt retirements Consumers FMBs $ 50 2.600 % October 2015 October 2015 Total Consumers $ 50 Total CMS Energy $ 50 FMBs: Consumers secures its FMBs by a mortgage and lien on substantially all of its property. Consumers’ ability to issue FMBs 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. Regulatory Authorization for Financings: Consumers is required to maintain FERC authorization for financings. In June 2014, 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, 2015 , Consumers had entered into short-term borrowing programs allowing it to issue up to $800 milli on in short-term securities; $249 million of securities were outstanding under these programs. FERC has also authorized Consumers to issue and sell up to $ 1.9 billion of secured and unsecured long-term securities for general corporate purposes. The remaining availability was $ 900 million at December 31, 2015 . The authorizations were effective July 1, 2014 and terminate June 30, 2016. 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, 2015 , the aggregate annual contractual maturities for long-term debt for the next five years were: In Millions 2016 2017 2018 2019 2020 CMS Energy, including Consumers Long-term debt $ 684 $ 1,010 $ 911 $ 1,288 $ 801 Consumers Long-term debt $ 198 $ 375 $ 523 $ 876 $ 426 Revolving Credit Facilities: The following secured revolving credit facilities with banks were available at December 31, 2015 : In Millions Amount of Amount Letters of Credit Amount Expiration Date Facility Borrowed Outstanding Available CMS Energy parent May 27, 2020 1 $ 550 $ - $ 1 $ 549 Consumers May 27, 2020 2 $ 650 $ - $ 9 $ 641 November 23, 2017 2,3 250 - - 250 May 9, 2018 2 30 - 30 - 1 Obligations under this facility are secured by Consumers common stock . 2 Obligations under this facility are secured by FMBs of Consumers. 3 In November 2015, Consumers entered into a new $250 million credit facility and terminated its $250 million accounts receivable sales program. 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 would not issue commercial paper in an amount exceeding the available revolver capacity. At December 31, 2015 , $ 249 million of commercial paper notes with a weighted - average annual interest rate of 0. 91 percent w as outstanding under this program. Dividend Restrictions: At December 31, 2015 , payment of dividends by CMS Energy on its common stock was limited to $ 3.9 billion under provisions of the Michigan Business Corporation Act of 1972 . Under the provisions of its articles of incorporation, at December 31, 2015 , Consumers had $ 884 million 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, 2015 , Consumers paid $ 474 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. In 2015, CMS Energy issued 888,610 shares of common stock at an average price of $33.76 per share, resulting in net proceeds of $30 million. 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 2015 2014 Cumulative, $100 par value, authorized 7,500,000 shares, with no mandatory redemption $ 4.50 $ 110.00 373,148 $ 37 $ 37

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
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. To the extent possible, CMS Energy and Consumers use quoted market prices or other observable market pricing data in valuing assets and liabilities measured at fair value. If this information is unavailable, they use market-corroborated data or reasonable estimates about market participant assumptions. 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 2015 2014 2015 2014 Assets 1 Cash equivalents $ 158 $ 110 $ - $ 19 Restricted cash equivalents 19 38 19 38 CMS Energy common stock - - 29 38 Nonqualified deferred compensation plan assets 10 8 7 6 DB SERP Cash equivalents 2 4 2 3 Mutual funds 146 127 104 90 Derivative instruments Commodity contracts 1 2 1 2 Total $ 336 $ 289 $ 162 $ 196 Liabilities 1 Nonqualified deferred compensation plan liabilities $ 10 $ 8 $ 7 $ 6 Derivative instruments Commodity contracts - 1 - 1 Total $ 10 $ 9 $ 7 $ 7 1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3 and which were insignificant at December 31, 2015 and 201 4 . Cash Equivalents: Cash equivalents and restricted cash equivalents consist of money market funds with daily liquidity. 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 that are publicly available and are the basis for transactions to buy or sell shares in each fund. 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: CMS Energy and Consumers value their DB SERP assets using a market approach that incorporates quoted market prices. 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 that are publicly available and are the basis for transactions to buy or sell shares in each fund. 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 since the fair value measurements incorporate assumptions that cannot be observed or confirmed through market transactions. 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 2015 2014 2013 CMS Energy, including Consumers Balance at beginning of period $ 1 $ 4 $ 2 Total losses included in earnings 1 (1) - - Total gains (losses) offset through regulatory accounting 2 (15) 3 Purchases 1 (1) - Settlements (2) 13 (1) Balance at end of period $ 1 $ 1 $ 4 Unrealized losses included in earnings relating to assets and liabilities still held at end of period 1 $ - $ - $ (1) Consumers Balance at beginning of period $ 1 $ 4 $ 2 Total gains (losses) offset through regulatory accounting 2 (15) 3 Purchases - (1) - Settlements (2) 13 (1) Balance at end of period $ 1 $ 1 $ 4 1 CMS Energy records realized and unrealized gains and losses for Level 3 recurring fair value measurements in earnings as a component of operating revenue or purchased and interchange power on its 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. To the extent possible, CMS Energy and Consumers use quoted market prices or other observable market pricing data in valuing assets and liabilities measured at fair value. If this information is unavailable, they use market-corroborated data or reasonable estimates about market participant assumptions. 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 2015 2014 2015 2014 Assets 1 Cash equivalents $ 158 $ 110 $ - $ 19 Restricted cash equivalents 19 38 19 38 CMS Energy common stock - - 29 38 Nonqualified deferred compensation plan assets 10 8 7 6 DB SERP Cash equivalents 2 4 2 3 Mutual funds 146 127 104 90 Derivative instruments Commodity contracts 1 2 1 2 Total $ 336 $ 289 $ 162 $ 196 Liabilities 1 Nonqualified deferred compensation plan liabilities $ 10 $ 8 $ 7 $ 6 Derivative instruments Commodity contracts - 1 - 1 Total $ 10 $ 9 $ 7 $ 7 1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3 and which were insignificant at December 31, 2015 and 201 4 . Cash Equivalents: Cash equivalents and restricted cash equivalents consist of money market funds with daily liquidity. 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 that are publicly available and are the basis for transactions to buy or sell shares in each fund. 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: CMS Energy and Consumers value their DB SERP assets using a market approach that incorporates quoted market prices. 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 that are publicly available and are the basis for transactions to buy or sell shares in each fund. 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 since the fair value measurements incorporate assumptions that cannot be observed or confirmed through market transactions. 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 2015 2014 2013 CMS Energy, including Consumers Balance at beginning of period $ 1 $ 4 $ 2 Total losses included in earnings 1 (1) - - Total gains (losses) offset through regulatory accounting 2 (15) 3 Purchases 1 (1) - Settlements (2) 13 (1) Balance at end of period $ 1 $ 1 $ 4 Unrealized losses included in earnings relating to assets and liabilities still held at end of period 1 $ - $ - $ (1) Consumers Balance at beginning of period $ 1 $ 4 $ 2 Total gains (losses) offset through regulatory accounting 2 (15) 3 Purchases - (1) - Settlements (2) 13 (1) Balance at end of period $ 1 $ 1 $ 4 1 CMS Energy records realized and unrealized gains and losses for Level 3 recurring fair value measurements in earnings as a component of operating revenue or purchased and interchange power on its consolidated statements of income.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2015
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 does not include information on cash, cash equivalents, short-term accounts and notes receivable, short-term investments, and current liabilities since the carrying amounts of these items approximate their fair values because of their short-term nature. 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, 2015 December 31, 2014 Fair Value Fair Value Carrying Level Carrying Level Amount Total 1 2 3 Amount Total 1 2 3 CMS Energy, including Consumers Securities held to maturity $ 11 $ 11 $ - $ 11 $ - $ 11 $ 11 $ - $ 11 $ - Notes payable 1 14 14 - - 14 - - - - - Notes receivable 2 1,161 1,228 - - 1,228 938 995 - - 995 Long-term debt 3 9,125 9,599 - 8,648 951 8,535 9,285 - 8,252 1,033 Consumers Long-term debt 4 $ 5,404 $ 5,684 $ - $ 4,733 $ 951 $ 5,278 $ 5,749 $ - $ 4,716 $ 1,033 1 Includes current portion of notes payable of $1 million at December 31, 2015 . 2 Includes current portion of notes receivable of $ 144 million at December 31, 2015 and $ 138 million at December 31, 2014 . 3 Includes current portion of long-term debt of $ 684 million at December 31, 2015 and $ 519 million at December 31, 2014 . 4 Includes current portion of long-term debt of $ 198 million at December 31, 2015 and $ 124 million at December 31, 2014 . Notes receivable consist 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, 2015 and 2014 , 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, 2015 December 31, 2014 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 $ 152 $ - $ 6 $ 146 $ 129 $ - $ 2 $ 127 Held to maturity Debt securities 11 - - 11 11 - - 11 Consumers Available for sale DB SERP Mutual funds $ 108 $ - $ 4 $ 104 $ 92 $ - $ 2 $ 90 CMS Energy common stock 4 25 - 29 5 33 - 38 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. 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 2015 2014 2013 CMS Energy, including Consumers Proceeds from sales of investment securities $ 3 $ 8 $ 3 Consumers Proceeds from sales of investment securities $ 2 $ 6 $ 2 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 gains of $ 9 million in 2015 and $4 million in 2013 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 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 does not include information on cash, cash equivalents, short-term accounts and notes receivable, short-term investments, and current liabilities since the carrying amounts of these items approximate their fair values because of their short-term nature. 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, 2015 December 31, 2014 Fair Value Fair Value Carrying Level Carrying Level Amount Total 1 2 3 Amount Total 1 2 3 CMS Energy, including Consumers Securities held to maturity $ 11 $ 11 $ - $ 11 $ - $ 11 $ 11 $ - $ 11 $ - Notes payable 1 14 14 - - 14 - - - - - Notes receivable 2 1,161 1,228 - - 1,228 938 995 - - 995 Long-term debt 3 9,125 9,599 - 8,648 951 8,535 9,285 - 8,252 1,033 Consumers Long-term debt 4 $ 5,404 $ 5,684 $ - $ 4,733 $ 951 $ 5,278 $ 5,749 $ - $ 4,716 $ 1,033 1 Includes current portion of notes payable of $1 million at December 31, 2015 . 2 Includes current portion of notes receivable of $ 144 million at December 31, 2015 and $ 138 million at December 31, 2014 . 3 Includes current portion of long-term debt of $ 684 million at December 31, 2015 and $ 519 million at December 31, 2014 . 4 Includes current portion of long-term debt of $ 198 million at December 31, 2015 and $ 124 million at December 31, 2014 . Notes receivable consist 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, 2015 and 2014 , 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, 2015 December 31, 2014 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 $ 152 $ - $ 6 $ 146 $ 129 $ - $ 2 $ 127 Held to maturity Debt securities 11 - - 11 11 - - 11 Consumers Available for sale DB SERP Mutual funds $ 108 $ - $ 4 $ 104 $ 92 $ - $ 2 $ 90 CMS Energy common stock 4 25 - 29 5 33 - 38 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. 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 2015 2014 2013 CMS Energy, including Consumers Proceeds from sales of investment securities $ 3 $ 8 $ 3 Consumers Proceeds from sales of investment securities $ 2 $ 6 $ 2 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 gains of $ 9 million in 2015 and $4 million in 2013 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.

Notes Receivable

Notes Receivable	12 Months Ended
	Dec. 31, 2015
Notes Receivable [Abstract]
Notes Receivable	8: N otes R eceivable Presented in the following table are details of CMS Energy’s current and non ‑current notes receivable: In Millions December 31 2015 2014 CMS Energy, including Consumers Current EnerBank notes receivable, net of allowance for loan losses $ 128 $ 97 EnerBank notes receivable held for sale 16 41 Other - 1 Non-current EnerBank notes receivable 1,017 800 Total notes receivable $ 1,161 $ 939 EnerBank notes receivable are unsecured consumer installment loans for financing home improvements. EnerBank records its notes receivable at cost, less allowance for loan losses. In May 2015, EnerBank completed a sale of notes receivable, receiving proceeds of $48 million and recording an insignificant gain. At December 31, 2015 , $ 16 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 2016. The allowance for loan losses is a valuation allowance to reflect estimated credit losses. The allowance is increased by the provision for loan losses and decreased by loan charge-offs net of recoveries. Management estimates the allowance balance required by taking into consideration historical loan loss experience, the nature and volume of the portfolio, economic conditions, and other factors. Loan losses are charged against the allowance when the loss is confirmed, but no later than the point at which a loan becomes 120 days past due. Presented in the following table are the changes in the allowance for loan losses: In Millions Years Ended December 31 2015 2014 Balance at beginning of period $ 8 $ 5 Charge-offs (8) (6) Recoveries 1 1 Provision for loan losses 8 8 Balance at end of period $ 9 $ 8 Loans that are 30 days or more past due are considered delinquent. The balance of EnerBank’s delinquent consumer loans was $ 8 million at December 31, 2015 and $ 5 million at December 31, 2014 . At December 31, 2015 and 2014 , $ 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, 2015
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 2015 2014 CMS Energy, including Consumers Electric Generation 22 - 125 $ 4,925 $ 4,544 Distribution 20 - 75 6,809 6,487 Other 5 - 50 1,039 910 Assets under capital leases and financing obligation 286 289 Gas Distribution 28 - 80 3,497 3,239 Transmission 17 - 75 981 974 Underground storage facilities 1 29 - 65 601 578 Other 5 - 50 630 538 Capital leases 14 6 Enterprises Independent power production 3 - 30 95 90 Other 3 - 40 25 25 Other 2 - 51 41 41 Construction work in progress 1,509 1,106 Less accumulated depreciation and amortization (5,747) (5,415) Net plant, property, and equipment 2 $ 14,705 $ 13,412 Consumers Electric Generation 22 - 125 $ 4,925 $ 4,544 Distribution 20 - 75 6,809 6,487 Other 5 - 50 1,039 910 Assets under capital leases and financing obligation 286 289 Gas Distribution 28 - 80 3,497 3,239 Transmission 17 - 75 981 974 Underground storage facilities 1 29 - 65 601 578 Other 5 - 50 630 538 Capital leases 14 6 Other non ‑utility property 8 - 51 15 15 Construction work in progress 1,467 1,103 Less accumulated depreciation and amortization (5,676) (5,346) Net plant, property, and equipment 2 $ 14,588 $ 13,337 1 Underground storage includes base natural gas of $26 million at December 31, 2015 and 2014 . Base natural gas is not subject to depreciation. 2 For the year ended December 31, 2015 , utility plant additions were $1 .4 billion and utility plant retirements were $1 87 million. For the year ended December 31, 2014 , utility plant additions were $ 1. 6 billion and utility plant retirements were $ 1 26 million. 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 2015 2014 2013 AFUDC capitalization rate 7.1 % 7.2 % 7.3 % 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 2015 2014 Consumers Balance at beginning of period $ 295 $ 291 Additions 17 7 Net retirements and other adjustments (12) (3) Balance at end of period $ 300 $ 295 Assets under capital leases and financing obligation are presented as gross amounts. Accumulated amortization of assets under capital leases and financing obligation was $ 152 million at December 31, 2015 and $ 1 43 million at December 31, 2014 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 2015 2014 CMS Energy, including Consumers Utility plant assets $ 5,674 $ 5,345 Non-utility plant assets 73 70 Consumers Utility plant assets $ 5,674 $ 5,345 Non-utility plant assets 2 1 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 2015 2014 2013 Electric utility property 3.5 % 3.5 % 3.5 % Gas utility property 2.8 2.8 2.8 Other property 8.7 7.7 7.0 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 2015 2014 2013 CMS Energy, including Consumers Depreciation expense – plant, property, and equipment $ 591 $ 551 $ 516 Amortization expense Software 70 50 40 Other intangible assets 4 4 3 Securitized regulatory assets 83 75 63 Other regulatory assets 2 5 6 Total depreciation and amortization expense $ 750 $ 685 $ 628 Consumers Depreciation expense – plant, property, and equipment $ 586 $ 546 $ 511 Amortization expense Software 69 49 39 Other intangible assets 4 3 3 Securitized regulatory assets 83 75 63 Other regulatory assets 2 5 6 Total depreciation and amortization expense $ 744 $ 678 $ 622 Amortization expense on intangible assets is expected to range between $84 million and $110 million per year over the next five years. 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, 2015 December 31, 2014 Description Amortization Life in Years Gross Cost 1 Accumulated Amortization Gross Cost 1 Accumulated Amortization CMS Energy, including Consumers Software development 2 - 15 $ 734 $ 294 $ 596 $ 223 Rights of way 50 - 75 153 46 150 44 Franchises and consents 5 - 30 15 8 15 8 Leasehold improvements various 2 7 5 5 4 Other intangibles various 21 15 21 14 Total $ 930 $ 368 $ 787 $ 293 Consumers Software development 3 - 15 $ 729 $ 291 $ 594 $ 221 Rights of way 50 - 75 153 46 150 44 Franchises and consents 5 - 30 15 8 15 8 Leasehold improvements various 2 7 5 5 4 Other intangibles various 21 15 21 14 Total $ 925 $ 365 $ 785 $ 291 1 Net intangible asset additions for Consumers’ utility plant were $ 140 million during 201 5 and $ 96 million during 201 4 and primarily represented software development costs. 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, 2015 : In Millions, Except Ownership Share J.H. Campbell Unit 3 Ludington Distribution Ownership share 93.3 % 51.0 % various Utility plant in service $ 1,078 $ 245 $ 200 Accumulated depreciation (542) (151) (63) Construction work in progress 494 157 4 Net investment $ 1,030 $ 251 $ 141 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 2015 2014 CMS Energy, including Consumers Electric Generation 22 - 125 $ 4,925 $ 4,544 Distribution 20 - 75 6,809 6,487 Other 5 - 50 1,039 910 Assets under capital leases and financing obligation 286 289 Gas Distribution 28 - 80 3,497 3,239 Transmission 17 - 75 981 974 Underground storage facilities 1 29 - 65 601 578 Other 5 - 50 630 538 Capital leases 14 6 Enterprises Independent power production 3 - 30 95 90 Other 3 - 40 25 25 Other 2 - 51 41 41 Construction work in progress 1,509 1,106 Less accumulated depreciation and amortization (5,747) (5,415) Net plant, property, and equipment 2 $ 14,705 $ 13,412 Consumers Electric Generation 22 - 125 $ 4,925 $ 4,544 Distribution 20 - 75 6,809 6,487 Other 5 - 50 1,039 910 Assets under capital leases and financing obligation 286 289 Gas Distribution 28 - 80 3,497 3,239 Transmission 17 - 75 981 974 Underground storage facilities 1 29 - 65 601 578 Other 5 - 50 630 538 Capital leases 14 6 Other non ‑utility property 8 - 51 15 15 Construction work in progress 1,467 1,103 Less accumulated depreciation and amortization (5,676) (5,346) Net plant, property, and equipment 2 $ 14,588 $ 13,337 1 Underground storage includes base natural gas of $26 million at December 31, 2015 and 2014 . Base natural gas is not subject to depreciation. 2 For the year ended December 31, 2015 , utility plant additions were $1 .4 billion and utility plant retirements were $1 87 million. For the year ended December 31, 2014 , utility plant additions were $ 1. 6 billion and utility plant retirements were $ 1 26 million. 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 2015 2014 2013 AFUDC capitalization rate 7.1 % 7.2 % 7.3 % 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 2015 2014 Consumers Balance at beginning of period $ 295 $ 291 Additions 17 7 Net retirements and other adjustments (12) (3) Balance at end of period $ 300 $ 295 Assets under capital leases and financing obligation are presented as gross amounts. Accumulated amortization of assets under capital leases and financing obligation was $ 152 million at December 31, 2015 and $ 1 43 million at December 31, 2014 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 2015 2014 CMS Energy, including Consumers Utility plant assets $ 5,674 $ 5,345 Non-utility plant assets 73 70 Consumers Utility plant assets $ 5,674 $ 5,345 Non-utility plant assets 2 1 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 2015 2014 2013 Electric utility property 3.5 % 3.5 % 3.5 % Gas utility property 2.8 2.8 2.8 Other property 8.7 7.7 7.0 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 2015 2014 2013 CMS Energy, including Consumers Depreciation expense – plant, property, and equipment $ 591 $ 551 $ 516 Amortization expense Software 70 50 40 Other intangible assets 4 4 3 Securitized regulatory assets 83 75 63 Other regulatory assets 2 5 6 Total depreciation and amortization expense $ 750 $ 685 $ 628 Consumers Depreciation expense – plant, property, and equipment $ 586 $ 546 $ 511 Amortization expense Software 69 49 39 Other intangible assets 4 3 3 Securitized regulatory assets 83 75 63 Other regulatory assets 2 5 6 Total depreciation and amortization expense $ 744 $ 678 $ 622 Amortization expense on intangible assets is expected to range between $84 million and $110 million per year over the next five years. 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, 2015 December 31, 2014 Description Amortization Life in Years Gross Cost 1 Accumulated Amortization Gross Cost 1 Accumulated Amortization CMS Energy, including Consumers Software development 2 - 15 $ 734 $ 294 $ 596 $ 223 Rights of way 50 - 75 153 46 150 44 Franchises and consents 5 - 30 15 8 15 8 Leasehold improvements various 2 7 5 5 4 Other intangibles various 21 15 21 14 Total $ 930 $ 368 $ 787 $ 293 Consumers Software development 3 - 15 $ 729 $ 291 $ 594 $ 221 Rights of way 50 - 75 153 46 150 44 Franchises and consents 5 - 30 15 8 15 8 Leasehold improvements various 2 7 5 5 4 Other intangibles various 21 15 21 14 Total $ 925 $ 365 $ 785 $ 291 1 Net intangible asset additions for Consumers’ utility plant were $ 140 million during 201 5 and $ 96 million during 201 4 and primarily represented software development costs. 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, 2015 : In Millions, Except Ownership Share J.H. Campbell Unit 3 Ludington Distribution Ownership share 93.3 % 51.0 % various Utility plant in service $ 1,078 $ 245 $ 200 Accumulated depreciation (542) (151) (63) Construction work in progress 494 157 4 Net investment $ 1,030 $ 251 $ 141 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

Leases	12 Months Ended
	Dec. 31, 2015
Leases	10: L eases 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 ten years and with extension provisions over the next 11 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 vehicles, 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 six years at December 31, 2015 . 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 two years at December 31, 2015 . The remaining terms of Consumers’ long-term PPAs accounted for as leases range between one and 17 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, 2015 , 2014 , and 2013 , all of CMS Energy’s minimum lease expense and contingent rental expense were attributable to Consumers. In Millions Years Ended December 31 2015 2014 2013 Consumers Minimum operating lease expense PPAs $ 6 $ 6 $ 6 Other agreements 19 19 21 Contingent rental expense 1 82 85 77 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, 2015 . All of CMS Energy’s non ‑cancelable leases at December 31, 2015 were attributable to Consumers. In Millions Capital Leases Financing 1 Operating Leases Consumers 2016 $ 14 $ 17 $ 20 2017 14 17 19 2018 13 16 16 2019 13 15 10 2020 11 14 10 2021 and thereafter 36 17 29 Total minimum lease payments $ 101 $ 96 $ 104 Less imputed interest 43 14 Present value of net minimum lease payments $ 58 $ 82 Less current portion 9 13 Non-current portion $ 49 $ 69 1 In 2007, Consumers sold Palisades to Entergy and entered into a 15 -year PPA to buy all of the capacity and energy then capable of being produced by Palisades. Consumers has continuing involvement with Palisades through security provided to Entergy for Consumers’ PPA obligation and other arrangements. Because of these ongoing arrangements, Consumers accounted for the transaction as a financing of Palisades and not a sale. Accordingly, no gain on the sale of Palisades was recognized on the consolidated statements of income. Consumers accounted for the remaining non-real-estate assets and liabilities associated with the transaction as a sale. Palisades remains on Consumers’ consolidated balance sheets and Consumers continues to depreciate it. Consumers recorded the related proceeds as a financing obligation with payments recorded to interest expense and the financing obligation based on the amortization of the obligation over the life of the Palisades PPA. The value of the financing obligation was determined based on an allocation of the transaction proceeds to the fair values of the net assets sold and fair value of the plant asset under the financing. Total amortization and interest charges under the financing were $18 million for the year ended December 31, 2015 , $19 million for the year ended December 31, 2014 , and $20 million for the year ended December 31, 2013 .
Consumers Energy Company [Member]
Leases	10: L eases 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 ten years and with extension provisions over the next 11 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 vehicles, 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 six years at December 31, 2015 . 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 two years at December 31, 2015 . The remaining terms of Consumers’ long-term PPAs accounted for as leases range between one and 17 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, 2015 , 2014 , and 2013 , all of CMS Energy’s minimum lease expense and contingent rental expense were attributable to Consumers. In Millions Years Ended December 31 2015 2014 2013 Consumers Minimum operating lease expense PPAs $ 6 $ 6 $ 6 Other agreements 19 19 21 Contingent rental expense 1 82 85 77 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, 2015 . All of CMS Energy’s non ‑cancelable leases at December 31, 2015 were attributable to Consumers. In Millions Capital Leases Financing 1 Operating Leases Consumers 2016 $ 14 $ 17 $ 20 2017 14 17 19 2018 13 16 16 2019 13 15 10 2020 11 14 10 2021 and thereafter 36 17 29 Total minimum lease payments $ 101 $ 96 $ 104 Less imputed interest 43 14 Present value of net minimum lease payments $ 58 $ 82 Less current portion 9 13 Non-current portion $ 49 $ 69 1 In 2007, Consumers sold Palisades to Entergy and entered into a 15 -year PPA to buy all of the capacity and energy then capable of being produced by Palisades. Consumers has continuing involvement with Palisades through security provided to Entergy for Consumers’ PPA obligation and other arrangements. Because of these ongoing arrangements, Consumers accounted for the transaction as a financing of Palisades and not a sale. Accordingly, no gain on the sale of Palisades was recognized on the consolidated statements of income. Consumers accounted for the remaining non-real-estate assets and liabilities associated with the transaction as a sale. Palisades remains on Consumers’ consolidated balance sheets and Consumers continues to depreciate it. Consumers recorded the related proceeds as a financing obligation with payments recorded to interest expense and the financing obligation based on the amortization of the obligation over the life of the Palisades PPA. The value of the financing obligation was determined based on an allocation of the transaction proceeds to the fair values of the net assets sold and fair value of the plant asset under the financing. Total amortization and interest charges under the financing were $18 million for the year ended December 31, 2015 , $19 million for the year ended December 31, 2014 , and $20 million for the year ended December 31, 2013 .

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2015
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. 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. For additional details, see Note 4, Contingencies and Commitments—Consumers E lectric Utility Contingencies— Electric Env ironmental Matters. 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: In-Service Company and ARO Description 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 wind parks 2012,2014 Wind 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 wind parks 2012,2014 Wind 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 12/31/2014 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 Wind parks 6 - - - - 6 Total Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438 In Millions ARO ARO Liability Cash flow Liability Company and ARO Description 12/31/2013 Incurred Settled Accretion Revisions 12/31/2014 CMS Energy, including Consumers Consumers $ 324 $ 9 $ (12) $ 18 $ - $ 339 Gas treating plant and gas wells 1 - - - - 1 Total CMS Energy $ 325 $ 9 $ (12) $ 18 $ - $ 340 Consumers Coal ash disposal areas $ 118 $ - $ (3) $ 5 $ - $ 120 Gas distribution cut, purge, and cap 154 6 (8) 10 - 162 Asbestos abatement 49 - (1) 3 - 51 Wind parks 3 3 - - - 6 Total Consumers $ 324 $ 9 $ (12) $ 18 $ - $ 339
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. 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. For additional details, see Note 4, Contingencies and Commitments—Consumers E lectric Utility Contingencies— Electric Env ironmental Matters. 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: In-Service Company and ARO Description 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 wind parks 2012,2014 Wind 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 wind parks 2012,2014 Wind 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 12/31/2014 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 Wind parks 6 - - - - 6 Total Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438 In Millions ARO ARO Liability Cash flow Liability Company and ARO Description 12/31/2013 Incurred Settled Accretion Revisions 12/31/2014 CMS Energy, including Consumers Consumers $ 324 $ 9 $ (12) $ 18 $ - $ 339 Gas treating plant and gas wells 1 - - - - 1 Total CMS Energy $ 325 $ 9 $ (12) $ 18 $ - $ 340 Consumers Coal ash disposal areas $ 118 $ - $ (3) $ 5 $ - $ 120 Gas distribution cut, purge, and cap 154 6 (8) 10 - 162 Asbestos abatement 49 - (1) 3 - 51 Wind parks 3 3 - - - 6 Total Consumers $ 324 $ 9 $ (12) $ 18 $ - $ 339

Retirement Benefits

Retirement Benefits	12 Months Ended
	Dec. 31, 2015
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 of six percent of base pay to the DCCP 401(k) plan for employees hired on or after September 1, 2005. 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 and Consumers was $ 16 million for the year ended December 31, 2015 , $ 13 million for the year ended December 31, 2014 , and $ 10 million for the year ended December 31, 2013 . 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 2015 2014 CMS Energy, including Consumers Trust assets $ 148 $ 131 ABO 140 145 Contributions 25 - Consumers Trust assets $ 106 $ 93 ABO 97 99 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 $ 2 million at December 31, 2015 and 2014 . 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, 2015 , 2014 , and 2013 . 401(k) Plan: T he 401(k) plan employer match equal s 60 percent of eligible contributions up to the first six percent of an employee’s wages. The total 401(k) plan cost for CMS Energy, including Consumers, and for Consumers was $19 million for the year ended December 31, 2015 , $ 18 million for the year ended December 31, 2014 , and $ 1 7 million for the year ended December 31, 2013 . 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 and 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 7.25 percent in 2016 and 6.50 percent in 2015 for those under 65 and would increase 8.00 percent in 2016 and 6.50 percent in 2015 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, 2015 Point Increase Point Decrease CMS Energy, including Consumers Effect on total service and interest cost component $ 11 $ (9) Effect on PBO 168 (137) Consumers Effect on total service and interest cost component $ 11 $ (9) Effect on PBO 164 (133) 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 2015 2014 2013 CMS Energy, including Consumers Weighted average for benefit obligations 1 Discount rate 2 DB Pension Plan 4.52 % 4.10 % 4.90 % DB SERP 4.43 4.10 4.90 OPEB Plan 4.70 4.30 5.10 Rate of compensation increase DB Pension Plan 3.00 3.00 3.00 DB SERP 5.50 5.50 5.50 Weighted average for net periodic benefit cost 1 Discount rate 2,3 DB Pension Plan 4.10 4.90 4.10 DB SERP 4.10 4.90 4.10 OPEB Plan 4.30 5.10 4.40 Expected long-term rate of return on plan assets 4 DB Pension Plan 7.50 7.50 7.75 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 2015 and 2014 for benefit obligations was based on the RP- 2014 mortality table, with projection scales MP-2015 for 2015 and MP-2014 for 2014 . The mortality assumption for 2013 was based on the RP - 2000 mortality tables with projection of future mortality improvements using Scale AA, which aligned with the IRS prescriptions for cash funding valuations under the Pension Protection Act of 2006. The mortality assumption for net periodic benefit cost for 2015 was based on the RP - 2014 mortality table with projection scale MP-2014, and for 2014 and 2013 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 in which they determine the discount rate used to calculate the service cost and interest expense 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 expense; 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. CMS Energy and Consumers expect that this change will result in a decrease in the service cost and interest expense components of net periodic benefit costs for the DB Pension and OPEB Plans, with an offsetting impact to the actuarial gain or loss recorded in, and later amortized from, the associated regulatory asset and AOCI. This change represents a change in accounting estimate and will not impact years prior to 2016. 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 7.5 percent in 201 5 . The actual return (loss) on DB Pension Plan assets was (2.0) percent in 201 5 , 7.4 percent in 2014 , and 12.5 percent in 201 3 . 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 2015 2014 2013 2015 2014 2013 CMS Energy, including Consumers Net periodic cost (credit) Service cost $ 50 $ 42 $ 54 $ 25 $ 20 $ 29 Interest expense 108 105 100 58 56 65 Expected return on plan assets (138) (135) (127) (91) (88) (77) Amortization of: Net loss 97 60 101 21 2 26 Prior service cost (credit) 1 1 3 (41) (41) (31) Net periodic cost (credit) $ 118 $ 73 $ 131 $ (28) $ (51) $ 12 Consumers Net periodic cost (credit) Service cost $ 49 $ 41 $ 52 $ 25 $ 20 $ 28 Interest expense 103 100 96 56 54 63 Expected return on plan assets (134) (131) (124) (86) (83) (72) Amortization of: Net loss 93 59 98 22 3 27 Prior service cost (credit) 1 1 3 (40) (40) (30) Net periodic cost (credit) $ 112 $ 70 $ 125 $ (23) $ (46) $ 16 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 2016 from or to the associated regulatory asset and AOCI: In Millions DB Pension Plan OPEB Plan CMS Energy, including Consumers Regulatory asset $ 72 $ (18) AOCI 1 (2) Consumers Regulatory asset $ 72 $ (18) 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 and 13 years for OPEB for the years ended December 31, 2015 , 2014 , and 2013 . 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 2013 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. 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 2015 2014 2015 2014 2015 2014 CMS Energy, including Consumers Benefit obligation at beginning of period $ 2,547 $ 2,073 $ 156 $ 132 $ 1,378 $ 1,123 Service cost 49 41 1 1 25 20 Interest cost 102 99 6 6 58 56 Plan amendments 13 - - - (25) - Actuarial (gain) loss (153) 458 1 (5) 24 (152) 230 1 Benefits paid (155) (124) (8) (7) (57) 2 (51) 2 Benefit obligation at end of period $ 2,403 $ 2,547 $ 150 $ 156 $ 1,227 $ 1,378 Plan assets at fair value at beginning of period $ 1,979 $ 1,964 $ - $ - $ 1,265 $ 1,218 Actual return on plan assets (36) 139 - - (29) 72 Company contribution 225 - 8 7 29 25 Actual benefits paid (155) (124) (8) (7) (57) 2 (50) 2 Plan assets at fair value at end of period $ 2,013 $ 1,979 $ - $ - $ 1,208 $ 1,265 Funded status $ (390) 3 $ (568) 3 $ (150) $ (156) $ (19) $ (113) Consumers Benefit obligation at beginning of period $ 111 $ 93 $ 1,336 $ 1,088 Service cost 1 1 25 20 Interest cost 4 4 56 54 Plan amendments - - (24) - Actuarial (gain) loss (5) 17 (150) 223 1 Benefits paid (5) (4) (55) 2 (49) 2 Benefit obligation at end of period $ 106 $ 111 $ 1,188 $ 1,336 Plan assets at fair value at beginning of period $ - $ - $ 1,186 $ 1,141 Actual return on plan assets - - (27) 68 Company contribution 5 4 29 25 Actual benefits paid (5) (4) (55) 2 (48) 2 Plan assets at fair value at end of period $ - $ - $ 1,133 $ 1,186 Funded status $ (106) $ (111) $ (55) $ (150) 1 The actuarial loss for 2014 was primarily the result of lowering the discount rates used in calculating the plans’ obligations and using the RP-2014 mortality table during the annual measurement of benefit obligations. 2 CMS Energy received less than $ 1 million in 2015, $4 million in 2014, and $ 5 million in 2013 for the Medicare Part D subsidies. Consumers received less than $1 million in 2015 and $ 4 million in each of 2014 and 2013 for the Medicare Part D subsidies. The Medicare Part D subsidy payments are used to pay OPEB Plan benefits. 3 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. At December 31, 2014 , $ 532 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’ assets (liabilities): In Millions December 31 2015 2014 CMS Energy, including Consumers Current assets (liabilities) DB SERP $ (8) $ (8) Non-current assets (liabilities) DB Pension Plan (390) (568) DB SERP (142) (148) OPEB Plan (19) (113) Consumers Current assets (liabilities) DB SERP $ (5) $ (5) Non-current assets (liabilities) DB Pension Plan (368) (532) DB SERP (101) (106) OPEB Plan (55) (150) Presented in the following table are the DB Pension Plan PBO, ABO, and fair value of plan assets: In Millions December 31 2015 2014 CMS Energy, including Consumers DB Pension Plan PBO $ 2,403 $ 2,547 DB Pension Plan ABO 2,140 2,257 Fair value of DB Pension Plan assets 2,013 1,979 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 2015 2014 2015 2014 CMS Energy, including Consumers Regulatory assets Net loss $ 944 $ 1,012 $ 360 $ 419 Prior service cost (credit) 19 7 (227) (243) Regulatory assets $ 963 $ 1,019 $ 133 $ 176 AOCI Net loss (gain) 86 99 (11) (18) Prior service cost (credit) 1 1 (8) (8) Total amounts recognized in regulatory assets and AOCI $ 1,050 $ 1,119 $ 114 $ 150 Consumers Regulatory assets Net loss $ 944 $ 1,012 $ 360 $ 419 Prior service cost (credit) 19 7 (227) (243) Regulatory assets $ 963 $ 1,019 $ 133 $ 176 AOCI Net loss (gain) 29 39 - - Total amounts recognized in regulatory assets and AOCI $ 992 $ 1,058 $ 133 $ 176 Plan Assets: Presented in the following tables are the fair values of CMS Energy’s and Consumers’ 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, 2015 December 31, 2014 Total Level 1 Level 2 Total Level 1 Level 2 CMS Energy, including Consumers Asset category Cash and short-term investments $ 215 $ 215 $ - $ 31 $ 31 $ - U.S. government and agencies securities 19 - 19 30 - 30 Corporate debt 243 - 243 222 - 222 State and municipal bonds 8 - 8 8 - 8 Foreign corporate bonds 16 - 16 21 - 21 Mutual funds 538 538 - 598 598 - Pooled funds 974 - 974 1,069 - 1,069 Total $ 2,013 $ 753 $ 1,260 $ 1,979 $ 629 $ 1,350 In Millions OPEB Plan December 31, 2015 December 31, 2014 Total Level 1 Level 2 Total Level 1 Level 2 CMS Energy, including Consumers Asset category Cash and short-term investments $ 51 $ 51 $ - $ 19 $ 19 $ - U.S. government and agencies securities 3 - 3 5 - 5 Corporate debt 34 - 34 33 - 33 State and municipal bonds 1 - 1 1 - 1 Foreign corporate bonds 2 - 2 3 - 3 Common stocks 54 54 - 69 69 - Mutual funds 456 456 - 438 438 - Pooled funds 607 - 607 697 - 697 Total $ 1,208 $ 561 $ 647 $ 1,265 $ 526 $ 739 Consumers Asset category Cash and short-term investments $ 48 $ 48 $ - $ 18 $ 18 $ - U.S. government and agencies securities 3 - 3 4 - 4 Corporate debt 32 - 32 31 - 31 State and municipal bonds 1 - 1 1 - 1 Foreign corporate bonds 2 - 2 3 - 3 Common stocks 51 51 - 65 65 - Mutual funds 427 427 - 411 411 - Pooled funds 569 - 569 653 - 653 Total $ 1,133 $ 526 $ 607 $ 1,186 $ 494 $ 692 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 2015 2014 2015 2014 U.S. equity securities 62 % 64 % 58 % 62 % Foreign equity securities 18 16 13 12 U.S. fixed-income securities 11 9 22 18 Foreign fixed-income securities 6 6 5 5 Alternative investments 3 5 2 3 100 % 100 % 100 % 100 % These investments were valued at the quoted NAV provided by the fund managers that is the basis for transactions to buy or sell shares in the funds. Target Asset Allocations: CMS Energy’s target asset allocation for DB Pension Plan assets is 50 percent equity, 30 percent fixed income, and 20 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 and Consumers use annual liability measurements, quarterly portfolio reviews, and periodic asset/liability studies to evaluate the need for adjustments to the portfolio allocation. CMS Energy and Consumers established union and non ‑union VEBA trusts to fund their 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 and Consumers’ target asset allocation for the trusts is 50 percent equity, 30 percent fixed income, and 20 percent alternative strategy investments. This target 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 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 and Consumers use 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 2015 2014 CMS Energy, including Consumers OPEB Plan VEBA trust $ 29 $ 16 401(h) component - 9 $ 29 $ 25 DB Pension Plan $ 225 $ - Consumers OPEB Plan VEBA trust $ 29 $ 16 401(h) component - 9 $ 29 $ 25 DB Pension Plan $ 209 $ - Contributions comprise required amounts and discretionary contributions. Neither CMS Energy nor Consumers plans to contribute to the OPEB or DB Pension Plans in 2016. 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 2016 $ 141 $ 8 $ 53 2017 146 8 57 2018 152 8 59 2019 156 9 63 2020 159 10 65 2021-2025 815 50 353 Consumers 2016 $ 137 $ 5 $ 51 2017 142 5 55 2018 148 5 57 2019 152 5 61 2020 155 6 63 2021-2025 793 30 341 Collective Bargaining Agreements: At December 31, 2015 , unions represented 40 percent of CMS Energy’s employees and 42 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 of six percent of base pay to the DCCP 401(k) plan for employees hired on or after September 1, 2005. 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 and Consumers was $ 16 million for the year ended December 31, 2015 , $ 13 million for the year ended December 31, 2014 , and $ 10 million for the year ended December 31, 2013 . 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 2015 2014 CMS Energy, including Consumers Trust assets $ 148 $ 131 ABO 140 145 Contributions 25 - Consumers Trust assets $ 106 $ 93 ABO 97 99 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 $ 2 million at December 31, 2015 and 2014 . 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, 2015 , 2014 , and 2013 . 401(k) Plan: T he 401(k) plan employer match equal s 60 percent of eligible contributions up to the first six percent of an employee’s wages. The total 401(k) plan cost for CMS Energy, including Consumers, and for Consumers was $19 million for the year ended December 31, 2015 , $ 18 million for the year ended December 31, 2014 , and $ 1 7 million for the year ended December 31, 2013 . 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 and 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 7.25 percent in 2016 and 6.50 percent in 2015 for those under 65 and would increase 8.00 percent in 2016 and 6.50 percent in 2015 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, 2015 Point Increase Point Decrease CMS Energy, including Consumers Effect on total service and interest cost component $ 11 $ (9) Effect on PBO 168 (137) Consumers Effect on total service and interest cost component $ 11 $ (9) Effect on PBO 164 (133) 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 2015 2014 2013 CMS Energy, including Consumers Weighted average for benefit obligations 1 Discount rate 2 DB Pension Plan 4.52 % 4.10 % 4.90 % DB SERP 4.43 4.10 4.90 OPEB Plan 4.70 4.30 5.10 Rate of compensation increase DB Pension Plan 3.00 3.00 3.00 DB SERP 5.50 5.50 5.50 Weighted average for net periodic benefit cost 1 Discount rate 2,3 DB Pension Plan 4.10 4.90 4.10 DB SERP 4.10 4.90 4.10 OPEB Plan 4.30 5.10 4.40 Expected long-term rate of return on plan assets 4 DB Pension Plan 7.50 7.50 7.75 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 2015 and 2014 for benefit obligations was based on the RP- 2014 mortality table, with projection scales MP-2015 for 2015 and MP-2014 for 2014 . The mortality assumption for 2013 was based on the RP - 2000 mortality tables with projection of future mortality improvements using Scale AA, which aligned with the IRS prescriptions for cash funding valuations under the Pension Protection Act of 2006. The mortality assumption for net periodic benefit cost for 2015 was based on the RP - 2014 mortality table with projection scale MP-2014, and for 2014 and 2013 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 in which they determine the discount rate used to calculate the service cost and interest expense 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 expense; 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. CMS Energy and Consumers expect that this change will result in a decrease in the service cost and interest expense components of net periodic benefit costs for the DB Pension and OPEB Plans, with an offsetting impact to the actuarial gain or loss recorded in, and later amortized from, the associated regulatory asset and AOCI. This change represents a change in accounting estimate and will not impact years prior to 2016. 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 7.5 percent in 201 5 . The actual return (loss) on DB Pension Plan assets was (2.0) percent in 201 5 , 7.4 percent in 2014 , and 12.5 percent in 201 3 . 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 2015 2014 2013 2015 2014 2013 CMS Energy, including Consumers Net periodic cost (credit) Service cost $ 50 $ 42 $ 54 $ 25 $ 20 $ 29 Interest expense 108 105 100 58 56 65 Expected return on plan assets (138) (135) (127) (91) (88) (77) Amortization of: Net loss 97 60 101 21 2 26 Prior service cost (credit) 1 1 3 (41) (41) (31) Net periodic cost (credit) $ 118 $ 73 $ 131 $ (28) $ (51) $ 12 Consumers Net periodic cost (credit) Service cost $ 49 $ 41 $ 52 $ 25 $ 20 $ 28 Interest expense 103 100 96 56 54 63 Expected return on plan assets (134) (131) (124) (86) (83) (72) Amortization of: Net loss 93 59 98 22 3 27 Prior service cost (credit) 1 1 3 (40) (40) (30) Net periodic cost (credit) $ 112 $ 70 $ 125 $ (23) $ (46) $ 16 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 2016 from or to the associated regulatory asset and AOCI: In Millions DB Pension Plan OPEB Plan CMS Energy, including Consumers Regulatory asset $ 72 $ (18) AOCI 1 (2) Consumers Regulatory asset $ 72 $ (18) 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 and 13 years for OPEB for the years ended December 31, 2015 , 2014 , and 2013 . 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 2013 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. 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 2015 2014 2015 2014 2015 2014 CMS Energy, including Consumers Benefit obligation at beginning of period $ 2,547 $ 2,073 $ 156 $ 132 $ 1,378 $ 1,123 Service cost 49 41 1 1 25 20 Interest cost 102 99 6 6 58 56 Plan amendments 13 - - - (25) - Actuarial (gain) loss (153) 458 1 (5) 24 (152) 230 1 Benefits paid (155) (124) (8) (7) (57) 2 (51) 2 Benefit obligation at end of period $ 2,403 $ 2,547 $ 150 $ 156 $ 1,227 $ 1,378 Plan assets at fair value at beginning of period $ 1,979 $ 1,964 $ - $ - $ 1,265 $ 1,218 Actual return on plan assets (36) 139 - - (29) 72 Company contribution 225 - 8 7 29 25 Actual benefits paid (155) (124) (8) (7) (57) 2 (50) 2 Plan assets at fair value at end of period $ 2,013 $ 1,979 $ - $ - $ 1,208 $ 1,265 Funded status $ (390) 3 $ (568) 3 $ (150) $ (156) $ (19) $ (113) Consumers Benefit obligation at beginning of period $ 111 $ 93 $ 1,336 $ 1,088 Service cost 1 1 25 20 Interest cost 4 4 56 54 Plan amendments - - (24) - Actuarial (gain) loss (5) 17 (150) 223 1 Benefits paid (5) (4) (55) 2 (49) 2 Benefit obligation at end of period $ 106 $ 111 $ 1,188 $ 1,336 Plan assets at fair value at beginning of period $ - $ - $ 1,186 $ 1,141 Actual return on plan assets - - (27) 68 Company contribution 5 4 29 25 Actual benefits paid (5) (4) (55) 2 (48) 2 Plan assets at fair value at end of period $ - $ - $ 1,133 $ 1,186 Funded status $ (106) $ (111) $ (55) $ (150) 1 The actuarial loss for 2014 was primarily the result of lowering the discount rates used in calculating the plans’ obligations and using the RP-2014 mortality table during the annual measurement of benefit obligations. 2 CMS Energy received less than $ 1 million in 2015, $4 million in 2014, and $ 5 million in 2013 for the Medicare Part D subsidies. Consumers received less than $1 million in 2015 and $ 4 million in each of 2014 and 2013 for the Medicare Part D subsidies. The Medicare Part D subsidy payments are used to pay OPEB Plan benefits. 3 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. At December 31, 2014 , $ 532 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’ assets (liabilities): In Millions December 31 2015 2014 CMS Energy, including Consumers Current assets (liabilities) DB SERP $ (8) $ (8) Non-current assets (liabilities) DB Pension Plan (390) (568) DB SERP (142) (148) OPEB Plan (19) (113) Consumers Current assets (liabilities) DB SERP $ (5) $ (5) Non-current assets (liabilities) DB Pension Plan (368) (532) DB SERP (101) (106) OPEB Plan (55) (150) Presented in the following table are the DB Pension Plan PBO, ABO, and fair value of plan assets: In Millions December 31 2015 2014 CMS Energy, including Consumers DB Pension Plan PBO $ 2,403 $ 2,547 DB Pension Plan ABO 2,140 2,257 Fair value of DB Pension Plan assets 2,013 1,979 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 2015 2014 2015 2014 CMS Energy, including Consumers Regulatory assets Net loss $ 944 $ 1,012 $ 360 $ 419 Prior service cost (credit) 19 7 (227) (243) Regulatory assets $ 963 $ 1,019 $ 133 $ 176 AOCI Net loss (gain) 86 99 (11) (18) Prior service cost (credit) 1 1 (8) (8) Total amounts recognized in regulatory assets and AOCI $ 1,050 $ 1,119 $ 114 $ 150 Consumers Regulatory assets Net loss $ 944 $ 1,012 $ 360 $ 419 Prior service cost (credit) 19 7 (227) (243) Regulatory assets $ 963 $ 1,019 $ 133 $ 176 AOCI Net loss (gain) 29 39 - - Total amounts recognized in regulatory assets and AOCI $ 992 $ 1,058 $ 133 $ 176 Plan Assets: Presented in the following tables are the fair values of CMS Energy’s and Consumers’ 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, 2015 December 31, 2014 Total Level 1 Level 2 Total Level 1 Level 2 CMS Energy, including Consumers Asset category Cash and short-term investments $ 215 $ 215 $ - $ 31 $ 31 $ - U.S. government and agencies securities 19 - 19 30 - 30 Corporate debt 243 - 243 222 - 222 State and municipal bonds 8 - 8 8 - 8 Foreign corporate bonds 16 - 16 21 - 21 Mutual funds 538 538 - 598 598 - Pooled funds 974 - 974 1,069 - 1,069 Total $ 2,013 $ 753 $ 1,260 $ 1,979 $ 629 $ 1,350 In Millions OPEB Plan December 31, 2015 December 31, 2014 Total Level 1 Level 2 Total Level 1 Level 2 CMS Energy, including Consumers Asset category Cash and short-term investments $ 51 $ 51 $ - $ 19 $ 19 $ - U.S. government and agencies securities 3 - 3 5 - 5 Corporate debt 34 - 34 33 - 33 State and municipal bonds 1 - 1 1 - 1 Foreign corporate bonds 2 - 2 3 - 3 Common stocks 54 54 - 69 69 - Mutual funds 456 456 - 438 438 - Pooled funds 607 - 607 697 - 697 Total $ 1,208 $ 561 $ 647 $ 1,265 $ 526 $ 739 Consumers Asset category Cash and short-term investments $ 48 $ 48 $ - $ 18 $ 18 $ - U.S. government and agencies securities 3 - 3 4 - 4 Corporate debt 32 - 32 31 - 31 State and municipal bonds 1 - 1 1 - 1 Foreign corporate bonds 2 - 2 3 - 3 Common stocks 51 51 - 65 65 - Mutual funds 427 427 - 411 411 - Pooled funds 569 - 569 653 - 653 Total $ 1,133 $ 526 $ 607 $ 1,186 $ 494 $ 692 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 2015 2014 2015 2014 U.S. equity securities 62 % 64 % 58 % 62 % Foreign equity securities 18 16 13 12 U.S. fixed-income securities 11 9 22 18 Foreign fixed-income securities 6 6 5 5 Alternative investments 3 5 2 3 100 % 100 % 100 % 100 % These investments were valued at the quoted NAV provided by the fund managers that is the basis for transactions to buy or sell shares in the funds. Target Asset Allocations: CMS Energy’s target asset allocation for DB Pension Plan assets is 50 percent equity, 30 percent fixed income, and 20 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 and Consumers use annual liability measurements, quarterly portfolio reviews, and periodic asset/liability studies to evaluate the need for adjustments to the portfolio allocation. CMS Energy and Consumers established union and non ‑union VEBA trusts to fund their 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 and Consumers’ target asset allocation for the trusts is 50 percent equity, 30 percent fixed income, and 20 percent alternative strategy investments. This target 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 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 and Consumers use 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 2015 2014 CMS Energy, including Consumers OPEB Plan VEBA trust $ 29 $ 16 401(h) component - 9 $ 29 $ 25 DB Pension Plan $ 225 $ - Consumers OPEB Plan VEBA trust $ 29 $ 16 401(h) component - 9 $ 29 $ 25 DB Pension Plan $ 209 $ - Contributions comprise required amounts and discretionary contributions. Neither CMS Energy nor Consumers plans to contribute to the OPEB or DB Pension Plans in 2016. 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 2016 $ 141 $ 8 $ 53 2017 146 8 57 2018 152 8 59 2019 156 9 63 2020 159 10 65 2021-2025 815 50 353 Consumers 2016 $ 137 $ 5 $ 51 2017 142 5 55 2018 148 5 57 2019 152 5 61 2020 155 6 63 2021-2025 793 30 341 Collective Bargaining Agreements: At December 31, 2015 , unions represented 40 percent of CMS Energy’s employees and 42 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, 2015
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 2015, 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 2015, 2014, or 2013. 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 5,611,442 shares of common stock under the PISP as of December 31, 2015 . 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 for 2015 and 2014 were in the form of performance-based, market-based, a nd time-lapse restricted stock. Prior to 2014, all grants were in the form of market-based and time-lapse restricted stock. Award recipients receive shares of CMS Energy common stock that have dividend and voting rights. In lieu of cash dividend payments, however, the 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 CMS Energy’s EPS growth relative to a peer group over a three -year period. The awards granted in 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 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 vested or were forfeited during 2015 . 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, 2015 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 1,679,595 $ 24.69 1,614,684 $ 24.71 Granted Restricted stock 789,602 36.84 750,262 36.83 Restricted stock units 13,180 34.25 12,837 34.25 Vested - restricted stock (793,103) 27.76 (756,286) 27.74 Forfeited - restricted stock (64,340) 26.93 (63,840) 26.93 Nonvested at end of period 1,624,934 $ 29.08 1,557,657 $ 29.06 Year Ended December 31, 2015 CMS Energy, including Consumers Consumers Granted Time-lapse awards 152,820 146,536 Market-based awards 158,385 149,909 Performance-based awards 158,385 149,909 Restricted stock units 12,848 12,514 Dividends on market-based awards 22,208 21,129 Dividends on performance-based awards 11,046 10,502 Dividends on restricted stock units 332 323 Additional market-based shares based on achievement of condition 286,758 272,277 Total granted 802,782 763,099 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 2015 2014 2013 Expected volatility 14.1 % 15.6 % 17.4 % Expected dividend yield 3.3 3.7 3.9 Risk-free rate 0.8 0.8 0.4 Presented in the following table is the weighted-average grant-date fair value of all awards under the PISP: Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Weighted-average grant-date fair value per share Restricted stock granted $ 36.84 $ 26.15 $ 16.65 Restricted stock units granted 34.25 - - Consumers Weighted-average grant-date fair value per share Restricted stock granted $ 36.83 $ 26.18 $ 16.76 Restricted stock units granted 34.25 - - Presented in the following table are amounts related to restricted stock awards and restricted stock units: In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Fair value of shares that vested during the year $ 29 $ 16 $ 10 Compensation expense recognized 20 14 14 Income tax benefit recognized 8 5 5 Consumers Fair value of shares that vested during the year $ 28 $ 15 $ 9 Compensation expense recognized 19 13 14 Income tax benefit recognized 7 5 5 At December 31, 2015 , $ 15 million of total unrecognized compensation cost was related to restricted stock for CMS Energy, including Consumers, and $ 15 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. Since CMS Energy has utilized tax loss carryforwards, CMS Energy was unable to realize excess federal tax benefits upon vesting of restricted stock. Therefore, CMS Energy did not recognize the related excess federal tax benefits in equity. Since CMS Energy is not in a loss position for state tax purposes, CMS Energy recognized the related state tax benefits of $1 million in equity in 2015 . As of December 31, 2015 , CMS Energy ha d $ 33 million of unrealized excess federal tax benefits.
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 2015, 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 2015, 2014, or 2013. 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 5,611,442 shares of common stock under the PISP as of December 31, 2015 . 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 for 2015 and 2014 were in the form of performance-based, market-based, a nd time-lapse restricted stock. Prior to 2014, all grants were in the form of market-based and time-lapse restricted stock. Award recipients receive shares of CMS Energy common stock that have dividend and voting rights. In lieu of cash dividend payments, however, the 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 CMS Energy’s EPS growth relative to a peer group over a three -year period. The awards granted in 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 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 vested or were forfeited during 2015 . 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, 2015 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 1,679,595 $ 24.69 1,614,684 $ 24.71 Granted Restricted stock 789,602 36.84 750,262 36.83 Restricted stock units 13,180 34.25 12,837 34.25 Vested - restricted stock (793,103) 27.76 (756,286) 27.74 Forfeited - restricted stock (64,340) 26.93 (63,840) 26.93 Nonvested at end of period 1,624,934 $ 29.08 1,557,657 $ 29.06 Year Ended December 31, 2015 CMS Energy, including Consumers Consumers Granted Time-lapse awards 152,820 146,536 Market-based awards 158,385 149,909 Performance-based awards 158,385 149,909 Restricted stock units 12,848 12,514 Dividends on market-based awards 22,208 21,129 Dividends on performance-based awards 11,046 10,502 Dividends on restricted stock units 332 323 Additional market-based shares based on achievement of condition 286,758 272,277 Total granted 802,782 763,099 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 2015 2014 2013 Expected volatility 14.1 % 15.6 % 17.4 % Expected dividend yield 3.3 3.7 3.9 Risk-free rate 0.8 0.8 0.4 Presented in the following table is the weighted-average grant-date fair value of all awards under the PISP: Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Weighted-average grant-date fair value per share Restricted stock granted $ 36.84 $ 26.15 $ 16.65 Restricted stock units granted 34.25 - - Consumers Weighted-average grant-date fair value per share Restricted stock granted $ 36.83 $ 26.18 $ 16.76 Restricted stock units granted 34.25 - - Presented in the following table are amounts related to restricted stock awards and restricted stock units: In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Fair value of shares that vested during the year $ 29 $ 16 $ 10 Compensation expense recognized 20 14 14 Income tax benefit recognized 8 5 5 Consumers Fair value of shares that vested during the year $ 28 $ 15 $ 9 Compensation expense recognized 19 13 14 Income tax benefit recognized 7 5 5 At December 31, 2015 , $ 15 million of total unrecognized compensation cost was related to restricted stock for CMS Energy, including Consumers, and $ 15 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. Since CMS Energy has utilized tax loss carryforwards, CMS Energy was unable to realize excess federal tax benefits upon vesting of restricted stock. Therefore, CMS Energy did not recognize the related excess federal tax benefits in equity. Since CMS Energy is not in a loss position for state tax purposes, CMS Energy recognized the related state tax benefits of $1 million in equity in 2015 . As of December 31, 2015 , CMS Energy ha d $ 33 million of unrealized excess federal tax benefits.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
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 2015 2014 2013 CMS Energy, including Consumers Income from continuing operations before income taxes $ 796 $ 729 $ 756 Income tax expense at statutory rate 279 255 265 Increase (decrease) in income taxes from: State and local income taxes, net of federal effect 39 36 37 Accelerated flow-through of regulatory tax benefits (39) (39) - Other, net (8) (2) - Income tax expense $ 271 $ 250 $ 302 Effective tax rate 34.0 % 34.3 % 39.9 % Consumers Income from continuing operations before income taxes $ 896 $ 873 $ 880 Income tax expense at statutory rate 314 306 308 Increase (decrease) in income taxes from: State and local income taxes, net of federal effect 42 42 43 Accelerated flow-through of regulatory tax benefits (39) (39) - Other, net (15) (3) (5) Income tax expense $ 302 $ 306 $ 346 Effective tax rate 33.7 % 35.1 % 39.3 % Prior to 2014, Consumers recognized the income tax benefits associated with the removal costs of plant placed in service before 1993 as payments were made and the tax benefits were flowed through to customers. In 2013, the MPSC issued an order authorizing Consumers to flow through to customers the income tax benefits on a straight-line basis over an accelerated period. This regulatory treatment, which Consumers implemented in January 2014, will accelerate the return of $ 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. This treatment reduced Consumers’ income tax expense by $ 39 million for each of the year s ended December 31, 2015 an d 2014 . Presented in the following table are the significant components of income tax expense on continuing operations: In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Current income taxes Federal $ - $ - $ - State and local 24 24 34 $ 24 $ 24 $ 34 Deferred income taxes Federal $ 192 $ 198 $ 248 State and local 36 31 23 $ 228 $ 229 $ 271 Deferred income tax credit 19 (3) (3) Tax expense $ 271 $ 250 $ 302 Consumers Current income taxes Federal $ 66 $ 8 $ 137 State and local 32 36 45 $ 98 $ 44 $ 182 Deferred income taxes Federal $ 153 $ 236 $ 147 State and local 32 29 20 $ 185 $ 265 $ 167 Deferred income tax credit 19 (3) (3) Tax expense $ 302 $ 306 $ 346 Presented in the following table are the principal components of deferred income tax assets (liabilities) recognized: In Millions December 31 2015 2014 CMS Energy, including Consumers Employee benefits $ (127) $ (72) Gas inventory (96) (117) Plant, property, and equipment (2,429) (2,217) Net regulatory tax liability 50 65 Reserves and accruals 59 63 Securitized costs (122) (144) Tax loss and credit carryforwards 657 676 Other (5) - $ (2,013) $ (1,746) Less valuation allowance (4) (2) Total net deferred income tax liabilities $ (2,017) $ (1,748) Deferred tax assets, net of valuation reserves $ 762 $ 802 Deferred tax liabilities (2,779) (2,550) Total net deferred income tax liabilities $ (2,017) $ (1,748) Consumers Employee benefits $ (156) $ (103) Gas inventory (96) (117) Plant, property, and equipment (2,457) (2,263) Net regulatory tax liability 50 65 Reserves and accruals 30 34 Securitized costs (122) (144) Tax loss and credit carryforwards 46 45 Other (5) (2) $ (2,710) $ (2,485) Less valuation allowance - (1) Total net deferred income tax liabilities $ (2,710) $ (2,486) Deferred tax assets, net of valuation reserves $ 126 $ 143 Deferred tax liabilities (2,836) (2,629) Total net deferred income tax liabilities $ (2,710) $ (2,486) 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, 2015 : In Millions Gross Amount Tax Attribute Expiration CMS Energy, including Consumers Federal net operating loss carryforward $ 885 $ 311 2025 – 2034 Local net operating loss carryforwards 414 4 2023 – 2034 Alternative minimum tax credits 270 270 No expiration Charitable contribution carryover 2 1 2016 – 2019 General business credits 71 71 2018 – 2035 Total tax attributes $ 657 Consumers Federal net operating loss carryforward $ 121 $ 42 2025 – 2034 Charitable contribution carryover 2 1 2016 – 2019 General business credits 3 3 2032 – 2035 Total tax attributes $ 46 CMS Energy has provided a valuation allowance of $ 1 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 2015 2014 2013 CMS Energy, including Consumers Balance at beginning of period $ 5 $ 4 $ 1 Additions for current-year tax positions 1 2 - Additions for prior-year tax positions 1 1 3 Reductions for prior-year tax positions (1) (2) - Balance at end of period $ 6 $ 5 $ 4 Consumers Balance at beginning of period $ 5 $ 4 $ 1 Additions for current-year tax positions 1 2 - Additions for prior-year tax positions 1 1 3 Reductions for prior-year tax positions (1) (2) - Balance at end of period $ 6 $ 5 $ 4 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, 2015 , 2014 , or 2013 . 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 federal income tax returns for 2012 and subsequent years remain subject to examination by the IRS. CMS Energy’s MCIT and MBT 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, 2015 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 2015 2014 2013 CMS Energy, including Consumers Income from continuing operations before income taxes $ 796 $ 729 $ 756 Income tax expense at statutory rate 279 255 265 Increase (decrease) in income taxes from: State and local income taxes, net of federal effect 39 36 37 Accelerated flow-through of regulatory tax benefits (39) (39) - Other, net (8) (2) - Income tax expense $ 271 $ 250 $ 302 Effective tax rate 34.0 % 34.3 % 39.9 % Consumers Income from continuing operations before income taxes $ 896 $ 873 $ 880 Income tax expense at statutory rate 314 306 308 Increase (decrease) in income taxes from: State and local income taxes, net of federal effect 42 42 43 Accelerated flow-through of regulatory tax benefits (39) (39) - Other, net (15) (3) (5) Income tax expense $ 302 $ 306 $ 346 Effective tax rate 33.7 % 35.1 % 39.3 % Prior to 2014, Consumers recognized the income tax benefits associated with the removal costs of plant placed in service before 1993 as payments were made and the tax benefits were flowed through to customers. In 2013, the MPSC issued an order authorizing Consumers to flow through to customers the income tax benefits on a straight-line basis over an accelerated period. This regulatory treatment, which Consumers implemented in January 2014, will accelerate the return of $ 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. This treatment reduced Consumers’ income tax expense by $ 39 million for each of the year s ended December 31, 2015 an d 2014 . Presented in the following table are the significant components of income tax expense on continuing operations: In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Current income taxes Federal $ - $ - $ - State and local 24 24 34 $ 24 $ 24 $ 34 Deferred income taxes Federal $ 192 $ 198 $ 248 State and local 36 31 23 $ 228 $ 229 $ 271 Deferred income tax credit 19 (3) (3) Tax expense $ 271 $ 250 $ 302 Consumers Current income taxes Federal $ 66 $ 8 $ 137 State and local 32 36 45 $ 98 $ 44 $ 182 Deferred income taxes Federal $ 153 $ 236 $ 147 State and local 32 29 20 $ 185 $ 265 $ 167 Deferred income tax credit 19 (3) (3) Tax expense $ 302 $ 306 $ 346 Presented in the following table are the principal components of deferred income tax assets (liabilities) recognized: In Millions December 31 2015 2014 CMS Energy, including Consumers Employee benefits $ (127) $ (72) Gas inventory (96) (117) Plant, property, and equipment (2,429) (2,217) Net regulatory tax liability 50 65 Reserves and accruals 59 63 Securitized costs (122) (144) Tax loss and credit carryforwards 657 676 Other (5) - $ (2,013) $ (1,746) Less valuation allowance (4) (2) Total net deferred income tax liabilities $ (2,017) $ (1,748) Deferred tax assets, net of valuation reserves $ 762 $ 802 Deferred tax liabilities (2,779) (2,550) Total net deferred income tax liabilities $ (2,017) $ (1,748) Consumers Employee benefits $ (156) $ (103) Gas inventory (96) (117) Plant, property, and equipment (2,457) (2,263) Net regulatory tax liability 50 65 Reserves and accruals 30 34 Securitized costs (122) (144) Tax loss and credit carryforwards 46 45 Other (5) (2) $ (2,710) $ (2,485) Less valuation allowance - (1) Total net deferred income tax liabilities $ (2,710) $ (2,486) Deferred tax assets, net of valuation reserves $ 126 $ 143 Deferred tax liabilities (2,836) (2,629) Total net deferred income tax liabilities $ (2,710) $ (2,486) 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, 2015 : In Millions Gross Amount Tax Attribute Expiration CMS Energy, including Consumers Federal net operating loss carryforward $ 885 $ 311 2025 – 2034 Local net operating loss carryforwards 414 4 2023 – 2034 Alternative minimum tax credits 270 270 No expiration Charitable contribution carryover 2 1 2016 – 2019 General business credits 71 71 2018 – 2035 Total tax attributes $ 657 Consumers Federal net operating loss carryforward $ 121 $ 42 2025 – 2034 Charitable contribution carryover 2 1 2016 – 2019 General business credits 3 3 2032 – 2035 Total tax attributes $ 46 CMS Energy has provided a valuation allowance of $ 1 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 2015 2014 2013 CMS Energy, including Consumers Balance at beginning of period $ 5 $ 4 $ 1 Additions for current-year tax positions 1 2 - Additions for prior-year tax positions 1 1 3 Reductions for prior-year tax positions (1) (2) - Balance at end of period $ 6 $ 5 $ 4 Consumers Balance at beginning of period $ 5 $ 4 $ 1 Additions for current-year tax positions 1 2 - Additions for prior-year tax positions 1 1 3 Reductions for prior-year tax positions (1) (2) - Balance at end of period $ 6 $ 5 $ 4 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, 2015 , 2014 , or 2013 . 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 federal income tax returns for 2012 and subsequent years remain subject to examination by the IRS. CMS Energy’s MCIT and MBT 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, 2015 were adequate for all years.

Earnings Per Share - CMS Energy

Earnings Per Share - CMS Energy	12 Months Ended
	Dec. 31, 2015
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 2015 2014 2013 Income available to common stockholders Net income $ 525 $ 479 $ 454 Less income attributable to noncontrolling interests 2 2 2 Net income available to common stockholders – basic and diluted $ 523 $ 477 $ 452 Average common shares outstanding Weighted-average shares – basic 275.6 270.6 264.5 Add dilutive contingently convertible securities - 3.1 6.4 Add dilutive nonvested stock awards 0.9 0.9 1.0 Weighted-average shares – diluted 276.5 274.6 271.9 Net income per average common share available to common stockholders Basic $ 1.90 $ 1.76 $ 1.71 Diluted 1.89 1.74 1.66 Dividends declared per common share $ 1.16 $ 1.08 $ 1.02 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, 2015
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 2015 2014 2013 CMS Energy, including Consumers Other income Fee income $ 9 $ 8 $ 7 All other 1 3 3 Total other income – CMS Energy $ 10 $ 11 $ 10 Consumers Other income Fee income $ 9 $ 8 $ 7 Gain on CMS Energy common stock 9 - 4 All other 1 2 3 Total other income – Consumers $ 19 $ 10 $ 14 CMS Energy, including Consumers Other expense Civic and political expenditures $ (10) $ (14) $ (5) Donations (1) (15) (4) Loss on reacquired and extinguished debt - (20) (4) All other (6) (6) (7) Total other expense – CMS Energy $ (17) $ (55) $ (20) Consumers Other expense Civic and political expenditures $ (10) $ (14) $ (5) Donations (1) (15) (4) All other (6) (6) (7) Total other expense – Consumers $ (17) $ (35) $ (16)
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 2015 2014 2013 CMS Energy, including Consumers Other income Fee income $ 9 $ 8 $ 7 All other 1 3 3 Total other income – CMS Energy $ 10 $ 11 $ 10 Consumers Other income Fee income $ 9 $ 8 $ 7 Gain on CMS Energy common stock 9 - 4 All other 1 2 3 Total other income – Consumers $ 19 $ 10 $ 14 CMS Energy, including Consumers Other expense Civic and political expenditures $ (10) $ (14) $ (5) Donations (1) (15) (4) Loss on reacquired and extinguished debt - (20) (4) All other (6) (6) (7) Total other expense – CMS Energy $ (17) $ (55) $ (20) Consumers Other expense Civic and political expenditures $ (10) $ (14) $ (5) Donations (1) (15) (4) All other (6) (6) (7) Total other expense – Consumers $ (17) $ (35) $ (16)

Reportable Segments

Reportable Segments	12 Months Ended
	Dec. 31, 2015
Reportable Segments	17: 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 2015 2014 2013 CMS Energy, including Consumers Operating revenue Electric utility $ 4,249 $ 4,436 $ 4,173 Gas utility 1,916 2,363 2,148 Enterprises 190 299 181 Other reconciling items 101 81 64 Total operating revenue – CMS Energy $ 6,456 $ 7,179 $ 6,566 Consumers Operating revenue Electric utility $ 4,249 $ 4,436 $ 4,173 Gas utility 1,916 2,363 2,148 Other reconciling items - 1 - Total operating revenue – Consumers $ 6,165 $ 6,800 $ 6,321 CMS Energy, including Consumers Depreciation and amortization Electric utility $ 567 $ 522 $ 484 Gas utility 177 156 138 Enterprises 4 4 3 Other reconciling items 2 3 3 Total depreciation and amortization – CMS Energy $ 750 $ 685 $ 628 Consumers Depreciation and amortization Electric utility $ 567 $ 522 $ 484 Gas utility 177 156 138 Total depreciation and amortization – Consumers $ 744 $ 678 $ 622 CMS Energy, including Consumers Income from equity method investees 1 Enterprises $ 14 $ 15 $ 13 Total income from equity method investees – CMS Energy $ 14 $ 15 $ 13 CMS Energy, including Consumers Interest charges Electric utility $ 178 $ 181 $ 179 Gas utility 71 67 64 Other reconciling items 147 159 155 Total interest charges – CMS Energy $ 396 $ 407 $ 398 Consumers Interest charges Electric utility $ 178 $ 181 $ 179 Gas utility 71 67 64 Other reconciling items 1 2 2 Total interest charges – Consumers $ 250 $ 250 $ 245 In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Income tax expense (benefit) Electric utility $ 224 $ 211 $ 242 Gas utility 78 95 104 Enterprises 3 (1) (4) Other reconciling items (34) (55) (40) Total income tax expense – CMS Energy $ 271 $ 250 $ 302 Consumers Income tax expense Electric utility $ 224 $ 211 $ 242 Gas utility 78 95 104 Total income tax expense – Consumers $ 302 $ 306 $ 346 CMS Energy, including Consumers Net income (loss) available to common stockholders Electric utility $ 437 $ 384 $ 363 Gas utility 154 179 168 Enterprises 4 (1) 2 Other reconciling items (72) (85) (81) Total net income available to common stockholders – CMS Energy $ 523 $ 477 $ 452 Consumers Net income available to common stockholder Electric utility $ 437 $ 384 $ 363 Gas utility 154 179 168 Other reconciling items 1 2 1 Total net income available to common stockholder – Consumers $ 592 $ 565 $ 532 CMS Energy, including Consumers Plant, property, and equipment, gross Electric utility $ 13,059 $ 12,230 $ 11,186 Gas utility 5,723 5,335 4,843 Enterprises 120 115 115 Other reconciling items 41 41 40 Total plant, property, and equipment, gross – CMS Energy $ 18,943 $ 17,721 $ 16,184 Consumers Plant, property, and equipment, gross Electric utility $ 13,059 $ 12,230 $ 11,186 Gas utility 5,723 5,335 4,843 Other reconciling items 15 15 15 Total plant, property, and equipment, gross – Consumers $ 18,797 $ 17,580 $ 16,044 CMS Energy, including Consumers Investments in equity method investees 1 Enterprises $ 61 $ 58 $ 57 Other reconciling items 3 3 2 Total investments in equity method investees – CMS Energy $ 64 $ 61 $ 59 In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Total assets Electric utility 2 $ 12,676 $ 11,582 $ 10,487 Gas utility 2 5,918 5,391 4,784 Enterprises 270 231 231 Other reconciling items 1,476 1,981 1,788 Total assets – CMS Energy $ 20,340 $ 19,185 $ 17,290 Consumers Total assets Electric utility 2 $ 12,676 $ 11,582 $ 10,487 Gas utility 2 5,918 5,391 4,784 Other reconciling items 64 874 908 Total assets – Consumers $ 18,658 $ 17,847 $ 16,179 CMS Energy, including Consumers Capital expenditures 3 Electric utility $ 1,136 $ 1,139 $ 996 Gas utility 558 473 407 Enterprises 44 3 1 Other reconciling items 3 1 4 Total capital expenditures – CMS Energy $ 1,741 $ 1,616 $ 1,408 Consumers Capital expenditures 3 Electric utility $ 1,136 $ 1,139 $ 996 Gas utility 558 473 407 Total capital expenditures – Consumers $ 1,694 $ 1,612 $ 1,403 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	17: 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 2015 2014 2013 CMS Energy, including Consumers Operating revenue Electric utility $ 4,249 $ 4,436 $ 4,173 Gas utility 1,916 2,363 2,148 Enterprises 190 299 181 Other reconciling items 101 81 64 Total operating revenue – CMS Energy $ 6,456 $ 7,179 $ 6,566 Consumers Operating revenue Electric utility $ 4,249 $ 4,436 $ 4,173 Gas utility 1,916 2,363 2,148 Other reconciling items - 1 - Total operating revenue – Consumers $ 6,165 $ 6,800 $ 6,321 CMS Energy, including Consumers Depreciation and amortization Electric utility $ 567 $ 522 $ 484 Gas utility 177 156 138 Enterprises 4 4 3 Other reconciling items 2 3 3 Total depreciation and amortization – CMS Energy $ 750 $ 685 $ 628 Consumers Depreciation and amortization Electric utility $ 567 $ 522 $ 484 Gas utility 177 156 138 Total depreciation and amortization – Consumers $ 744 $ 678 $ 622 CMS Energy, including Consumers Income from equity method investees 1 Enterprises $ 14 $ 15 $ 13 Total income from equity method investees – CMS Energy $ 14 $ 15 $ 13 CMS Energy, including Consumers Interest charges Electric utility $ 178 $ 181 $ 179 Gas utility 71 67 64 Other reconciling items 147 159 155 Total interest charges – CMS Energy $ 396 $ 407 $ 398 Consumers Interest charges Electric utility $ 178 $ 181 $ 179 Gas utility 71 67 64 Other reconciling items 1 2 2 Total interest charges – Consumers $ 250 $ 250 $ 245 In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Income tax expense (benefit) Electric utility $ 224 $ 211 $ 242 Gas utility 78 95 104 Enterprises 3 (1) (4) Other reconciling items (34) (55) (40) Total income tax expense – CMS Energy $ 271 $ 250 $ 302 Consumers Income tax expense Electric utility $ 224 $ 211 $ 242 Gas utility 78 95 104 Total income tax expense – Consumers $ 302 $ 306 $ 346 CMS Energy, including Consumers Net income (loss) available to common stockholders Electric utility $ 437 $ 384 $ 363 Gas utility 154 179 168 Enterprises 4 (1) 2 Other reconciling items (72) (85) (81) Total net income available to common stockholders – CMS Energy $ 523 $ 477 $ 452 Consumers Net income available to common stockholder Electric utility $ 437 $ 384 $ 363 Gas utility 154 179 168 Other reconciling items 1 2 1 Total net income available to common stockholder – Consumers $ 592 $ 565 $ 532 CMS Energy, including Consumers Plant, property, and equipment, gross Electric utility $ 13,059 $ 12,230 $ 11,186 Gas utility 5,723 5,335 4,843 Enterprises 120 115 115 Other reconciling items 41 41 40 Total plant, property, and equipment, gross – CMS Energy $ 18,943 $ 17,721 $ 16,184 Consumers Plant, property, and equipment, gross Electric utility $ 13,059 $ 12,230 $ 11,186 Gas utility 5,723 5,335 4,843 Other reconciling items 15 15 15 Total plant, property, and equipment, gross – Consumers $ 18,797 $ 17,580 $ 16,044 CMS Energy, including Consumers Investments in equity method investees 1 Enterprises $ 61 $ 58 $ 57 Other reconciling items 3 3 2 Total investments in equity method investees – CMS Energy $ 64 $ 61 $ 59 In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Total assets Electric utility 2 $ 12,676 $ 11,582 $ 10,487 Gas utility 2 5,918 5,391 4,784 Enterprises 270 231 231 Other reconciling items 1,476 1,981 1,788 Total assets – CMS Energy $ 20,340 $ 19,185 $ 17,290 Consumers Total assets Electric utility 2 $ 12,676 $ 11,582 $ 10,487 Gas utility 2 5,918 5,391 4,784 Other reconciling items 64 874 908 Total assets – Consumers $ 18,658 $ 17,847 $ 16,179 CMS Energy, including Consumers Capital expenditures 3 Electric utility $ 1,136 $ 1,139 $ 996 Gas utility 558 473 407 Enterprises 44 3 1 Other reconciling items 3 1 4 Total capital expenditures – CMS Energy $ 1,741 $ 1,616 $ 1,408 Consumers Capital expenditures 3 Electric utility $ 1,136 $ 1,139 $ 996 Gas utility 558 473 407 Total capital expenditures – Consumers $ 1,694 $ 1,612 $ 1,403 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, 2015
Consumers Energy Company [Member]
Related Party Transactions - Consumers	18: R elated -P arty T ransactions —C onsumers Consumers enters into a number of transactions with related parties. These transactions include: · purchase s of electricity from affiliates of CMS Enterprises · payment s 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 2015 2014 2013 Purchases of capacity and energy Affiliates of CMS Enterprises $ 83 $ 89 $ 89 Amounts payable to related parties for purchased power and other services were $23 million at December 31, 2015 and $ 12 million at December 31, 2014 . 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. Accounts receivable from related parties were $1 million at December 31, 2014. Consumers owned shares of CMS Energy common stock with a fair value of $ 2 9 million at December 31, 2015 . For additional details on Consumers’ investment in CMS Energy common stock, see Note 7, Financial Instruments. In January 2016, Consumers renewed a short-term credit agreement with CMS Energy, permitting Consumers to borrow up to $300 million. At December 31, 2015 , there were no outstanding loans under the agreement.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2015
Variable Interest Entities [Abstract]
Variable Interest Entities	19: V ariable I nterest E ntities CMS Energy has variable interests in T.E.S. Filer City, Grayling, and Genesee. CMS Energy is not the primary beneficiary of any of these partnerships because power is shared among unrelated parties, and no one party has the power 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 Non-recourse long-term debt that matured in December 2007. Grayling ( 50% ) Wood waste-fueled power generator Sale of revenue bonds that were retired in March 2012. 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. CMS Energy has operating and management contracts with Grayling and Genesee, and Consumers is the primary purchaser of power from each partnership 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 wood waste. 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 $ 59 million as of December 31, 2015 and $ 57 million as of December 31, 2014 . 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, 2015
Quarterly Financial and Common Stock Information	20: Q uarterly Financial and Common Stock Information (Unaudited) 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 In Millions, Except Per Share Amounts and Stock Prices 2014 Quarters Ended March 31 June 30 Sept 30 Dec 31 CMS Energy, including Consumers Operating revenue $ 2,523 $ 1,468 $ 1,430 $ 1,758 Operating income 408 235 236 273 Net income 204 84 94 97 Income attributable to noncontrolling interests - 1 - 1 Net income available to common stockholders 204 83 94 96 Basic earnings per average common share 1 0.77 0.31 0.34 0.35 Diluted earnings per average common share 1 0.75 0.30 0.34 0.35 Common stock prices 2 High 29.28 31.15 30.87 36.42 Low 26.12 28.87 28.18 29.78 Consumers Operating revenue $ 2,382 $ 1,387 $ 1,359 $ 1,672 Operating income 399 227 245 264 Net income 221 109 119 118 Preferred stock dividends - 1 - 1 Net income available to common stockholder 221 108 119 117 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	20: Q uarterly Financial and Common Stock Information (Unaudited) 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 In Millions, Except Per Share Amounts and Stock Prices 2014 Quarters Ended March 31 June 30 Sept 30 Dec 31 CMS Energy, including Consumers Operating revenue $ 2,523 $ 1,468 $ 1,430 $ 1,758 Operating income 408 235 236 273 Net income 204 84 94 97 Income attributable to noncontrolling interests - 1 - 1 Net income available to common stockholders 204 83 94 96 Basic earnings per average common share 1 0.77 0.31 0.34 0.35 Diluted earnings per average common share 1 0.75 0.30 0.34 0.35 Common stock prices 2 High 29.28 31.15 30.87 36.42 Low 26.12 28.87 28.18 29.78 Consumers Operating revenue $ 2,382 $ 1,387 $ 1,359 $ 1,672 Operating income 399 227 245 264 Net income 221 109 119 118 Preferred stock dividends - 1 - 1 Net income available to common stockholder 221 108 119 117 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, 2015
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 2015 2014 2013 Operating Expenses Other operating expenses $ (9) $ (6) $ (6) Total operating expenses (9) (6) (6) Operating Loss (9) (6) (6) Other Income (Expense) Equity earnings of subsidiaries 625 585 566 Interest income 1 1 1 Other expense (9) (20) (8) Total other income 617 566 559 Interest Charges Interest on long-term debt 134 150 148 Intercompany interest expense and other 3 2 3 Total interest charges 137 152 151 Income Before Income Taxes 471 408 402 Income Tax Benefit (52) (69) (50) Net Income Available to Common Stockholders $ 523 $ 477 $ 452 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 2015 2014 2013 Cash Flows from Operating Activities Net income $ 523 $ 477 $ 452 Adjustments to reconcile net income to net cash provided by operating activities Equity earnings of subsidiaries (625) (585) (566) Dividends received from subsidiaries 499 544 435 Deferred income taxes (24) 30 48 Cash provided by (used in) changes in assets and liabilities Accounts and notes receivable (86) (3) (3) Accounts payable 16 (2) 2 Accrued taxes (115) 97 48 Other current and non ‑current assets and liabilities 21 31 18 Net cash provided by operating activities 209 589 434 Cash Flows from Investing Activities Investment in subsidiaries (150) (495) (150) Return of capital - 178 - Net cash used in investing activities (150) (317) (150) Cash Flows from Financing Activities Proceeds from issuance of long-term debt 349 550 275 Issuance of common stock 43 43 36 Retirement of long-term debt (100) (547) (275) Payment of dividends on common stock (320) (293) (271) Debt issuance costs and financing fees (3) (6) (4) Decrease in notes payable (28) (19) (47) Net cash used in financing activities (59) (272) (286) Net Decrease in Cash and Cash Equivalents - - (2) Cash and Cash Equivalents, Beginning of Period - - 2 Cash and Cash Equivalents, 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 2015 2014 Current Assets Notes and accrued interest receivable $ 88 $ 2 Accounts receivable, including intercompany and related parties 9 9 Total current assets 97 11 Plant, Property, and Equipment Plant, property, and equipment, gross 16 16 Less accumulated depreciation and amortization 16 16 Total plant, property, and equipment - - Other Non-current Assets Deferred income taxes 340 317 Investments in subsidiaries 6,240 5,961 Other investments – DB SERP 26 22 Other 23 23 Total other non ‑current assets 6,629 6,323 Total Assets $ 6,726 $ 6,334 LIABILITIES AND EQUITY In Millions December 31 2015 2014 Current Liabilities Accounts and notes payable, including intercompany and related parties $ 74 $ 86 Accrued interest, including intercompany 38 37 Accrued taxes 23 138 Other current liabilities 5 4 Total current liabilities 140 265 Non-current Liabilities Long-term debt 2,630 2,380 Unamortized discount (7) (7) Postretirement benefits 22 24 Other non ‑current liabilities 3 2 Total non ‑current liabilities 2,648 2,399 Equity Common stockholders’ equity 3,938 3,670 Total Liabilities and Equity $ 6,726 $ 6,334 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 $ 328 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 agree ments 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 DOE on behalf of Consumers, in connection with Consumers’ 2011 settlement agreement with the DOE regarding damages resulting from the DOE’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, 2015
Schedule II - Valuation and Qualifying Accounts and Reserves	CMS Energy Corporation Schedule II – Valuation and Qualifying Accounts and Reserves Years Ended December 31, 2015 , 2014 , and 2013 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 2015 $ 40 $ 50 $ - $ 62 $ 28 2014 33 72 - 65 40 2013 32 63 - 62 33 Deferred tax valuation allowance 2015 $ 2 $ 3 $ (1) $ - $ 4 2014 2 - - - 2 2013 3 - - 1 2 Allowance for notes receivable 1 2015 $ 8 $ 8 $ - $ 7 $ 9 2014 5 8 - 5 8 2013 5 4 - 4 5 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, 2015 , 2014 , and 2013 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 2015 $ 39 $ 50 $ - $ 61 $ 28 2014 31 72 - 64 39 2013 30 63 - 62 31 Deferred tax valuation allowance 2015 $ 1 $ - $ (1) $ - $ - 2014 1 - - - 1 2013 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, 2015 , 2014 , and 2013 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 2015 $ 40 $ 50 $ - $ 62 $ 28 2014 33 72 - 65 40 2013 32 63 - 62 33 Deferred tax valuation allowance 2015 $ 2 $ 3 $ (1) $ - $ 4 2014 2 - - - 2 2013 3 - - 1 2 Allowance for notes receivable 1 2015 $ 8 $ 8 $ - $ 7 $ 9 2014 5 8 - 5 8 2013 5 4 - 4 5 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, 2015 , 2014 , and 2013 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 2015 $ 39 $ 50 $ - $ 61 $ 28 2014 31 72 - 64 39 2013 30 63 - 62 31 Deferred tax valuation allowance 2015 $ 1 $ - $ (1) $ - $ - 2014 1 - - - 1 2013 1 - - - 1 1 Deductions are write-offs of uncollectible accounts, net of recoveries.

Significant Accounting Polici31

Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2015
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: In 2009, the MPSC approved an energy optimization incentive mechanism that 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.
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.
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, which is recorded as a reduction to notes receivable on CMS Energy’s consolidated balance sheets, was $82 million at December 31, 2015 and $62 million at December 31, 2014. 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.
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.
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. 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. 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 because: · 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. CMS Energy and Consumers did not have significant amounts recorded as derivative assets or liabilities at December 31, 2015 or 2014 . Additionally, the gains and losses recognized in earnings were insignificant for the years ended December 31, 2015 , 2014 , and 2013 .
Determination of Pension and OPEB MRV of Plan Assets	Determination of MRV of Plan Assets for DB Pension Plan and OPEB Plan: CMS Energy and Consumers determine the MRV 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. CMS Energy and Consumers use the MRV in the calculation of net DB Pension Plan and OPEB Plan costs. For further details, see Note 12, Retirement Benefits.
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.
Inventory - Impairment	CMS Energy and Consumers use the lower-of-cost-or-market method to evaluate inventory for impairment.
Accounting for 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. Consumers recorded the deferred income taxes related to the grant as a reduction of the book basis of Lake Winds ® Energy Park.
Restricted Cash and Cash Equivalents	Restricted Cash and Cash Equivalents: CMS Energy and Consumers have restricted cash and cash equivalents dedicated for repayment of Securitization bonds and for payment under performance guarantees. CMS Energy and Consumers classify these amounts as a current asset if they relate to payments that could or will occur within one year. Changes in restricted cash and cash equivalents are presented as investing activities on the consolidated statements of cash flows.
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: In 2009, the MPSC approved an energy optimization incentive mechanism that 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.
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.
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.
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.
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. 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. 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 because: · 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. CMS Energy and Consumers did not have significant amounts recorded as derivative assets or liabilities at December 31, 2015 or 2014 . Additionally, the gains and losses recognized in earnings were insignificant for the years ended December 31, 2015 , 2014 , and 2013 .
Determination of Pension and OPEB MRV of Plan Assets	Determination of MRV of Plan Assets for DB Pension Plan and OPEB Plan: CMS Energy and Consumers determine the MRV 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. CMS Energy and Consumers use the MRV in the calculation of net DB Pension Plan and OPEB Plan costs. For further details, see Note 12, Retirement Benefits.
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.
Inventory - Impairment	CMS Energy and Consumers use the lower-of-cost-or-market method to evaluate inventory for impairment.
Accounting for 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. Consumers recorded the deferred income taxes related to the grant as a reduction of the book basis of Lake Winds ® Energy Park.
Restricted Cash and Cash Equivalents	Restricted Cash and Cash Equivalents: CMS Energy and Consumers have restricted cash and cash equivalents dedicated for repayment of Securitization bonds and for payment under performance guarantees. CMS Energy and Consumers classify these amounts as a current asset if they relate to payments that could or will occur within one year. Changes in restricted cash and cash equivalents are presented as investing activities on the consolidated statements of cash flows.

Notes Receivable (Policy)

Notes Receivable (Policy)	12 Months Ended
	Dec. 31, 2015
Notes Receivable [Abstract]
Allowance For Loan Losses Policy	The allowance for loan losses is a valuation allowance to reflect estimated credit losses. The allowance is increased by the provision for loan losses and decreased by loan charge-offs net of recoveries. Management estimates the allowance balance required by taking into consideration historical loan loss experience, the nature and volume of the portfolio, economic conditions, and other factors. Loan losses are charged against the allowance when the loss is confirmed, but no later than the point at which a loan becomes 120 days past due.

Income Taxes (Policy)

Income Taxes (Policy)	12 Months Ended
	Dec. 31, 2015
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.

Regulatory Matters (Tables)

Regulatory Matters (Tables) - Consumers Energy Company [Member]	12 Months Ended
	Dec. 31, 2015
Public Utility, Property, Plant and Equipment [Line Items]
Schedule of Regulatory Assets and Liabilities	In Millions December 31 End of Recovery or Refund Period 2015 2014 Regulatory assets Current Energy optimization plan incentive 1 2016 $ 16 $ 17 Securitized costs – electric utility restructuring legislation 2 2015 - 61 Major maintenance 2 2015 - 8 Other 2015 - 3 Total current regulatory assets $ 16 $ 89 Non-current Postretirement benefits 3 various $ 1,096 $ 1,195 Securitized costs – electric generating units to be retired 2 2029 348 370 ARO 4 various 151 139 MGP sites 4 various 146 147 Unamortized debt costs 4 various 61 66 Gas storage inventory adjustments 4 various 18 21 Energy optimization plan incentive 1 2017 18 17 Other various 2 1 Total non ‑current regulatory assets $ 1,840 $ 1,956 Total regulatory assets $ 1,856 $ 2,045 Regulatory liabilities Current Income taxes, net 2016 $ 64 $ 64 Securitized costs – electric utility restructuring legislation 2016 14 - Other 2016 4 3 Total current regulatory liabilities $ 82 $ 67 Non-current Cost of removal various $ 1,745 $ 1,673 Renewable energy plan 2028 109 131 ARO various 73 83 Income taxes, net various 64 103 Renewable energy grant 2043 60 63 Energy optimization plan various 26 32 Other various 11 10 Total non ‑current regulatory liabilities $ 2,088 $ 2,095 Total regulatory liabilities $ 2,170 $ 2,162 1 These regulatory assets have arisen from alternative revenue programs and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return. 2 These regulatory assets are included in rate base (or are expected to be included, for costs incurred subsequent to the most recently approved rate case), thereby providing a return on expenditures, or provide a specific return on investment authorized by the MPSC. 3 This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return. 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 2015 2014 Assets Accrued gas revenue $ - $ 27 Liabilities Accrued rate refunds 26 6

Contingencies And Commitments (

Contingencies And Commitments (Tables)	12 Months Ended
	Dec. 31, 2015
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 $ 143 $ 7 Guarantees 2 Various Indefinite 51 - Consumers Guarantee 2 July 2011 Indefinite $ 30 $ - 1 The se 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 DOE in connection with a settlement agreement regarding damages resulting from the DOE’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 DOE and CMS Energy’s 1994 guarantee of non-recourse revenue bonds issued by Genesee. For additional details on this guarantee, see Note 19, Variable Interest Entities.
Purchase Obligations	In Millions Payments Due Total 2016 2017 2018 2019 2020 Beyond 2020 CMS Energy, including Consumers Total PPAs $ 9,947 $ 999 $ 1,027 $ 969 $ 1,003 $ 995 $ 4,954 Other 2,200 904 580 251 111 63 291 Consumers PPAs MCV PPA $ 3,003 $ 335 $ 345 $ 277 $ 321 $ 296 $ 1,429 Palisades PPA 2,327 342 352 363 374 387 509 Related party PPAs 977 82 82 82 85 87 559 Other PPAs 3,640 240 248 247 223 225 2,457 Total PPAs $ 9,947 $ 999 $ 1,027 $ 969 $ 1,003 $ 995 $ 4,954 Other 1,908 870 551 224 83 34 146
Consumers Energy Company [Member]
Site Contingency [Line Items]
Expected Remediation Cost By Year	In Millions 2016 2017 2018 2019 2020 Consumers Remediation and other response activity costs $ 14 $ 19 $ 11 $ 14 $ 19
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 $ 143 $ 7 Guarantees 2 Various Indefinite 51 - Consumers Guarantee 2 July 2011 Indefinite $ 30 $ - 1 The se 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 DOE in connection with a settlement agreement regarding damages resulting from the DOE’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 DOE and CMS Energy’s 1994 guarantee of non-recourse revenue bonds issued by Genesee. For additional details on this guarantee, see Note 19, Variable Interest Entities.
Purchase Obligations	In Millions Payments Due Total 2016 2017 2018 2019 2020 Beyond 2020 CMS Energy, including Consumers Total PPAs $ 9,947 $ 999 $ 1,027 $ 969 $ 1,003 $ 995 $ 4,954 Other 2,200 904 580 251 111 63 291 Consumers PPAs MCV PPA $ 3,003 $ 335 $ 345 $ 277 $ 321 $ 296 $ 1,429 Palisades PPA 2,327 342 352 363 374 387 509 Related party PPAs 977 82 82 82 85 87 559 Other PPAs 3,640 240 248 247 223 225 2,457 Total PPAs $ 9,947 $ 999 $ 1,027 $ 969 $ 1,003 $ 995 $ 4,954 Other 1,908 870 551 224 83 34 146
Bay Harbor [Member]
Site Contingency [Line Items]
Expected Remediation Cost By Year	In Millions 2016 2017 2018 2019 2020 CMS Energy Long-term liquid disposal and operating and maintenance costs $ 6 $ 5 $ 5 $ 5 $ 4

Financings And Capitalization (

Financings And Capitalization (Tables)	12 Months Ended
	Dec. 31, 2015
Summary Of Long-Term Debt Outstanding	In Millions Interest Rate (%) Maturity 2015 2014 CMS Energy parent Senior notes 6.550 2017 $ 250 $ 250 5.050 2018 250 250 8.750 2019 300 300 6.250 2020 300 300 5.050 2022 300 300 3.875 2024 250 250 3.600 2025 250 - 4.700 2043 250 250 4.875 2044 300 300 Total CMS Energy senior notes $ 2,450 $ 2,200 Term loan facility variable 1 2017 180 180 Total CMS Energy parent $ 2,630 $ 2,380 Consumers $ 5,409 $ 5,283 Other CMS Energy subsidiaries EnerBank certificates of deposit 1.365 2 2016 -2025 $ 1,098 $ 884 Total other CMS Energy subsidiaries $ 1,098 $ 884 Total CMS Energy principal amount outstanding $ 9,137 $ 8,547 Current amounts (684) (519) Net unamortized discounts (12) (12) Total CMS Energy long-term debt $ 8,441 $ 8,016 1 Outstanding borrowings bear interest at an annual interest rate of LIBOR plus 0.85 percent ( 1.19 percent at December 31, 2015 ). 2 The weighted-average interest rate for EnerBank’s certificates of deposit was 1.36 percent at December 31, 2015 and 1. 22 percent at December 31, 2014 . EnerBank’s primary deposit product consists of brokered certificates of deposit with varying maturities and having a face value of $ 1,000 .
Summary Of Major Long-Term Debt Transactions	Principal Issue/Retirement (In Millions) Interest Rate Date Maturity Date Debt issuances CMS Energy parent Senior notes $ 250 3.600 % November 2015 November 2025 Total CMS Energy parent $ 250 Consumers FMBs $ 250 4.100 % November 2015 November 2045 Total Consumers $ 250 Total CMS Energy $ 500 Debt retirements Consumers FMBs $ 50 2.600 % October 2015 October 2015 Total Consumers $ 50 Total CMS Energy $ 50
Debt Maturities	In Millions 2016 2017 2018 2019 2020 CMS Energy, including Consumers Long-term debt $ 684 $ 1,010 $ 911 $ 1,288 $ 801 Consumers Long-term debt $ 198 $ 375 $ 523 $ 876 $ 426
Revolving Credit Facilities	In Millions Amount of Amount Letters of Credit Amount Expiration Date Facility Borrowed Outstanding Available CMS Energy parent May 27, 2020 1 $ 550 $ - $ 1 $ 549 Consumers May 27, 2020 2 $ 650 $ - $ 9 $ 641 November 23, 2017 2,3 250 - - 250 May 9, 2018 2 30 - 30 - 1 Obligations under this facility are secured by Consumers common stock . 2 Obligations under this facility are secured by FMBs of Consumers. 3 In November 2015, Consumers entered into a new $250 million credit facility and terminated its $250 million accounts receivable sales program.
Consumers Energy Company [Member]
Summary Of Long-Term Debt Outstanding	In Millions Interest Rate (%) Maturity 2015 2014 Consumers FMBs 1 2.600 2015 $ - $ 50 5.500 2016 173 173 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 - 4.350 2064 250 250 $ 4,773 $ 4,573 Securitization bonds 5.760 2015 - 49 2.689 2 2020-2029 3 353 378 $ 353 $ 427 Senior notes 6.875 2018 180 180 Tax-exempt pollution control revenue bonds various 2018-2035 103 103 Total Consumers principal amount outstanding $ 5,409 $ 5,283 Current amounts (198) (124) Net unamortized discounts (5) (5) Total Consumers long-term debt $ 5,206 $ 5,154 1 The weighted-average interest rate for Consumers’ FMBs was 4.73 percent at December 31, 2015 and 4.75 percent at December 31, 2014 . 2 The weighted-average interest rate for Consumers’ Securitization bonds issued through its subsidiary Consumers 2014 Securitization Funding was 2.69 percent at December 31, 2015 and 2.60 percent at December 31, 2014 . 3 Principal and interest payments are made semiannually.
Summary Of Major Long-Term Debt Transactions	Principal Issue/Retirement (In Millions) Interest Rate Date Maturity Date Debt issuances CMS Energy parent Senior notes $ 250 3.600 % November 2015 November 2025 Total CMS Energy parent $ 250 Consumers FMBs $ 250 4.100 % November 2015 November 2045 Total Consumers $ 250 Total CMS Energy $ 500 Debt retirements Consumers FMBs $ 50 2.600 % October 2015 October 2015 Total Consumers $ 50 Total CMS Energy $ 50
Debt Maturities	In Millions 2016 2017 2018 2019 2020 CMS Energy, including Consumers Long-term debt $ 684 $ 1,010 $ 911 $ 1,288 $ 801 Consumers Long-term debt $ 198 $ 375 $ 523 $ 876 $ 426
Revolving Credit Facilities	In Millions Amount of Amount Letters of Credit Amount Expiration Date Facility Borrowed Outstanding Available CMS Energy parent May 27, 2020 1 $ 550 $ - $ 1 $ 549 Consumers May 27, 2020 2 $ 650 $ - $ 9 $ 641 November 23, 2017 2,3 250 - - 250 May 9, 2018 2 30 - 30 - 1 Obligations under this facility are secured by Consumers common stock . 2 Obligations under this facility are secured by FMBs of Consumers. 3 In November 2015, Consumers entered into a new $250 million credit facility and terminated its $250 million accounts receivable sales program.
Issuance Of Stock	Optional Number of Balance Redemption Shares Outstanding Series Price Outstanding (In Millions) December 31 2015 2014 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, 2015
Assets And Liabilities Measured At Fair Value On A Recurring Basis	In Millions CMS Energy, including Consumers Consumers December 31 2015 2014 2015 2014 Assets 1 Cash equivalents $ 158 $ 110 $ - $ 19 Restricted cash equivalents 19 38 19 38 CMS Energy common stock - - 29 38 Nonqualified deferred compensation plan assets 10 8 7 6 DB SERP Cash equivalents 2 4 2 3 Mutual funds 146 127 104 90 Derivative instruments Commodity contracts 1 2 1 2 Total $ 336 $ 289 $ 162 $ 196 Liabilities 1 Nonqualified deferred compensation plan liabilities $ 10 $ 8 $ 7 $ 6 Derivative instruments Commodity contracts - 1 - 1 Total $ 10 $ 9 $ 7 $ 7 1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3 and which were insignificant at December 31, 2015 and 201 4 .
Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Level 3 Inputs	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Balance at beginning of period $ 1 $ 4 $ 2 Total losses included in earnings 1 (1) - - Total gains (losses) offset through regulatory accounting 2 (15) 3 Purchases 1 (1) - Settlements (2) 13 (1) Balance at end of period $ 1 $ 1 $ 4 Unrealized losses included in earnings relating to assets and liabilities still held at end of period 1 $ - $ - $ (1) Consumers Balance at beginning of period $ 1 $ 4 $ 2 Total gains (losses) offset through regulatory accounting 2 (15) 3 Purchases - (1) - Settlements (2) 13 (1) Balance at end of period $ 1 $ 1 $ 4 1 CMS Energy records realized and unrealized gains and losses for Level 3 recurring fair value measurements in earnings as a component of operating revenue or purchased and interchange power on its 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 2015 2014 2015 2014 Assets 1 Cash equivalents $ 158 $ 110 $ - $ 19 Restricted cash equivalents 19 38 19 38 CMS Energy common stock - - 29 38 Nonqualified deferred compensation plan assets 10 8 7 6 DB SERP Cash equivalents 2 4 2 3 Mutual funds 146 127 104 90 Derivative instruments Commodity contracts 1 2 1 2 Total $ 336 $ 289 $ 162 $ 196 Liabilities 1 Nonqualified deferred compensation plan liabilities $ 10 $ 8 $ 7 $ 6 Derivative instruments Commodity contracts - 1 - 1 Total $ 10 $ 9 $ 7 $ 7 1 All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3 and which were insignificant at December 31, 2015 and 201 4 .
Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Level 3 Inputs	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Balance at beginning of period $ 1 $ 4 $ 2 Total losses included in earnings 1 (1) - - Total gains (losses) offset through regulatory accounting 2 (15) 3 Purchases 1 (1) - Settlements (2) 13 (1) Balance at end of period $ 1 $ 1 $ 4 Unrealized losses included in earnings relating to assets and liabilities still held at end of period 1 $ - $ - $ (1) Consumers Balance at beginning of period $ 1 $ 4 $ 2 Total gains (losses) offset through regulatory accounting 2 (15) 3 Purchases - (1) - Settlements (2) 13 (1) Balance at end of period $ 1 $ 1 $ 4 1 CMS Energy records realized and unrealized gains and losses for Level 3 recurring fair value measurements in earnings as a component of operating revenue or purchased and interchange power on its consolidated statements of income.

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule Of Carrying Amounts And Fair Values Of Financial Instruments	In Millions December 31, 2015 December 31, 2014 Fair Value Fair Value Carrying Level Carrying Level Amount Total 1 2 3 Amount Total 1 2 3 CMS Energy, including Consumers Securities held to maturity $ 11 $ 11 $ - $ 11 $ - $ 11 $ 11 $ - $ 11 $ - Notes payable 1 14 14 - - 14 - - - - - Notes receivable 2 1,161 1,228 - - 1,228 938 995 - - 995 Long-term debt 3 9,125 9,599 - 8,648 951 8,535 9,285 - 8,252 1,033 Consumers Long-term debt 4 $ 5,404 $ 5,684 $ - $ 4,733 $ 951 $ 5,278 $ 5,749 $ - $ 4,716 $ 1,033 1 Includes current portion of notes payable of $1 million at December 31, 2015 . 2 Includes current portion of notes receivable of $ 144 million at December 31, 2015 and $ 138 million at December 31, 2014 . 3 Includes current portion of long-term debt of $ 684 million at December 31, 2015 and $ 519 million at December 31, 2014 . 4 Includes current portion of long-term debt of $ 198 million at December 31, 2015 and $ 124 million at December 31, 2014 .
Schedule Of Investment Securities	In Millions December 31, 2015 December 31, 2014 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 $ 152 $ - $ 6 $ 146 $ 129 $ - $ 2 $ 127 Held to maturity Debt securities 11 - - 11 11 - - 11 Consumers Available for sale DB SERP Mutual funds $ 108 $ - $ 4 $ 104 $ 92 $ - $ 2 $ 90 CMS Energy common stock 4 25 - 29 5 33 - 38
Schedule Of Proceeds And Gross Realized Gains/Losses From Sales Of Available-For-Sale Securities	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Proceeds from sales of investment securities $ 3 $ 8 $ 3 Consumers Proceeds from sales of investment securities $ 2 $ 6 $ 2
Consumers Energy Company [Member]
Schedule Of Carrying Amounts And Fair Values Of Financial Instruments	In Millions December 31, 2015 December 31, 2014 Fair Value Fair Value Carrying Level Carrying Level Amount Total 1 2 3 Amount Total 1 2 3 CMS Energy, including Consumers Securities held to maturity $ 11 $ 11 $ - $ 11 $ - $ 11 $ 11 $ - $ 11 $ - Notes payable 1 14 14 - - 14 - - - - - Notes receivable 2 1,161 1,228 - - 1,228 938 995 - - 995 Long-term debt 3 9,125 9,599 - 8,648 951 8,535 9,285 - 8,252 1,033 Consumers Long-term debt 4 $ 5,404 $ 5,684 $ - $ 4,733 $ 951 $ 5,278 $ 5,749 $ - $ 4,716 $ 1,033 1 Includes current portion of notes payable of $1 million at December 31, 2015 . 2 Includes current portion of notes receivable of $ 144 million at December 31, 2015 and $ 138 million at December 31, 2014 . 3 Includes current portion of long-term debt of $ 684 million at December 31, 2015 and $ 519 million at December 31, 2014 . 4 Includes current portion of long-term debt of $ 198 million at December 31, 2015 and $ 124 million at December 31, 2014 .
Schedule Of Investment Securities	In Millions December 31, 2015 December 31, 2014 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 $ 152 $ - $ 6 $ 146 $ 129 $ - $ 2 $ 127 Held to maturity Debt securities 11 - - 11 11 - - 11 Consumers Available for sale DB SERP Mutual funds $ 108 $ - $ 4 $ 104 $ 92 $ - $ 2 $ 90 CMS Energy common stock 4 25 - 29 5 33 - 38
Schedule Of Proceeds And Gross Realized Gains/Losses From Sales Of Available-For-Sale Securities	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Proceeds from sales of investment securities $ 3 $ 8 $ 3 Consumers Proceeds from sales of investment securities $ 2 $ 6 $ 2

Notes Receivable (Tables)

Notes Receivable (Tables)	12 Months Ended
	Dec. 31, 2015
Notes Receivable [Abstract]
Schedule Of Current And Non-Current Notes Receivable	In Millions December 31 2015 2014 CMS Energy, including Consumers Current EnerBank notes receivable, net of allowance for loan losses $ 128 $ 97 EnerBank notes receivable held for sale 16 41 Other - 1 Non-current EnerBank notes receivable 1,017 800 Total notes receivable $ 1,161 $ 939
Schedule Of Allowance For Loan Losses	In Millions Years Ended December 31 2015 2014 Balance at beginning of period $ 8 $ 5 Charge-offs (8) (6) Recoveries 1 1 Provision for loan losses 8 8 Balance at end of period $ 9 $ 8

Plant, Property, and Equipment

Plant, Property, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule Of Property, Plant And Equipment	In Millions December 31 Estimated Depreciable Life in Years 2015 2014 CMS Energy, including Consumers Electric Generation 22 - 125 $ 4,925 $ 4,544 Distribution 20 - 75 6,809 6,487 Other 5 - 50 1,039 910 Assets under capital leases and financing obligation 286 289 Gas Distribution 28 - 80 3,497 3,239 Transmission 17 - 75 981 974 Underground storage facilities 1 29 - 65 601 578 Other 5 - 50 630 538 Capital leases 14 6 Enterprises Independent power production 3 - 30 95 90 Other 3 - 40 25 25 Other 2 - 51 41 41 Construction work in progress 1,509 1,106 Less accumulated depreciation and amortization (5,747) (5,415) Net plant, property, and equipment 2 $ 14,705 $ 13,412 Consumers Electric Generation 22 - 125 $ 4,925 $ 4,544 Distribution 20 - 75 6,809 6,487 Other 5 - 50 1,039 910 Assets under capital leases and financing obligation 286 289 Gas Distribution 28 - 80 3,497 3,239 Transmission 17 - 75 981 974 Underground storage facilities 1 29 - 65 601 578 Other 5 - 50 630 538 Capital leases 14 6 Other non ‑utility property 8 - 51 15 15 Construction work in progress 1,467 1,103 Less accumulated depreciation and amortization (5,676) (5,346) Net plant, property, and equipment 2 $ 14,588 $ 13,337 1 Underground storage includes base natural gas of $26 million at December 31, 2015 and 2014 . Base natural gas is not subject to depreciation. 2 For the year ended December 31, 2015 , utility plant additions were $1 .4 billion and utility plant retirements were $1 87 million. For the year ended December 31, 2014 , utility plant additions were $ 1. 6 billion and utility plant retirements were $ 1 26 million.
Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization Table	In Millions December 31 2015 2014 CMS Energy, including Consumers Utility plant assets $ 5,674 $ 5,345 Non-utility plant assets 73 70 Consumers Utility plant assets $ 5,674 $ 5,345 Non-utility plant assets 2 1
Schedule Of Depriciation And Amortization	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Depreciation expense – plant, property, and equipment $ 591 $ 551 $ 516 Amortization expense Software 70 50 40 Other intangible assets 4 4 3 Securitized regulatory assets 83 75 63 Other regulatory assets 2 5 6 Total depreciation and amortization expense $ 750 $ 685 $ 628 Consumers Depreciation expense – plant, property, and equipment $ 586 $ 546 $ 511 Amortization expense Software 69 49 39 Other intangible assets 4 3 3 Securitized regulatory assets 83 75 63 Other regulatory assets 2 5 6 Total depreciation and amortization expense $ 744 $ 678 $ 622
Schedule of Finite-Lived Intangible Assets by Major Class Table	In Millions December 31, 2015 December 31, 2014 Description Amortization Life in Years Gross Cost 1 Accumulated Amortization Gross Cost 1 Accumulated Amortization CMS Energy, including Consumers Software development 2 - 15 $ 734 $ 294 $ 596 $ 223 Rights of way 50 - 75 153 46 150 44 Franchises and consents 5 - 30 15 8 15 8 Leasehold improvements various 2 7 5 5 4 Other intangibles various 21 15 21 14 Total $ 930 $ 368 $ 787 $ 293 Consumers Software development 3 - 15 $ 729 $ 291 $ 594 $ 221 Rights of way 50 - 75 153 46 150 44 Franchises and consents 5 - 30 15 8 15 8 Leasehold improvements various 2 7 5 5 4 Other intangibles various 21 15 21 14 Total $ 925 $ 365 $ 785 $ 291 1 Net intangible asset additions for Consumers’ utility plant were $ 140 million during 201 5 and $ 96 million during 201 4 and primarily represented software development costs. 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 $ 1,078 $ 245 $ 200 Accumulated depreciation (542) (151) (63) Construction work in progress 494 157 4 Net investment $ 1,030 $ 251 $ 141
Consumers Energy Company [Member]
Schedule Of Property, Plant And Equipment	In Millions December 31 Estimated Depreciable Life in Years 2015 2014 CMS Energy, including Consumers Electric Generation 22 - 125 $ 4,925 $ 4,544 Distribution 20 - 75 6,809 6,487 Other 5 - 50 1,039 910 Assets under capital leases and financing obligation 286 289 Gas Distribution 28 - 80 3,497 3,239 Transmission 17 - 75 981 974 Underground storage facilities 1 29 - 65 601 578 Other 5 - 50 630 538 Capital leases 14 6 Enterprises Independent power production 3 - 30 95 90 Other 3 - 40 25 25 Other 2 - 51 41 41 Construction work in progress 1,509 1,106 Less accumulated depreciation and amortization (5,747) (5,415) Net plant, property, and equipment 2 $ 14,705 $ 13,412 Consumers Electric Generation 22 - 125 $ 4,925 $ 4,544 Distribution 20 - 75 6,809 6,487 Other 5 - 50 1,039 910 Assets under capital leases and financing obligation 286 289 Gas Distribution 28 - 80 3,497 3,239 Transmission 17 - 75 981 974 Underground storage facilities 1 29 - 65 601 578 Other 5 - 50 630 538 Capital leases 14 6 Other non ‑utility property 8 - 51 15 15 Construction work in progress 1,467 1,103 Less accumulated depreciation and amortization (5,676) (5,346) Net plant, property, and equipment 2 $ 14,588 $ 13,337 1 Underground storage includes base natural gas of $26 million at December 31, 2015 and 2014 . Base natural gas is not subject to depreciation. 2 For the year ended December 31, 2015 , utility plant additions were $1 .4 billion and utility plant retirements were $1 87 million. For the year ended December 31, 2014 , utility plant additions were $ 1. 6 billion and utility plant retirements were $ 1 26 million.
Schedule of Capital Leased Asssets Table	In Millions Years Ended December 31 2015 2014 Consumers Balance at beginning of period $ 295 $ 291 Additions 17 7 Net retirements and other adjustments (12) (3) Balance at end of period $ 300 $ 295
Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization Table	In Millions December 31 2015 2014 CMS Energy, including Consumers Utility plant assets $ 5,674 $ 5,345 Non-utility plant assets 73 70 Consumers Utility plant assets $ 5,674 $ 5,345 Non-utility plant assets 2 1
Public Utilities Property Plant and Equipment Schedule of Composite Depreciation Rate Table	Years Ended December 31 2015 2014 2013 Electric utility property 3.5 % 3.5 % 3.5 % Gas utility property 2.8 2.8 2.8 Other property 8.7 7.7 7.0
Public Utilities, Allowance for Funds Used During Construction, Schedule of Composite Rate Table	Years Ended December 31 2015 2014 2013 AFUDC capitalization rate 7.1 % 7.2 % 7.3 %
Schedule Of Depriciation And Amortization	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Depreciation expense – plant, property, and equipment $ 591 $ 551 $ 516 Amortization expense Software 70 50 40 Other intangible assets 4 4 3 Securitized regulatory assets 83 75 63 Other regulatory assets 2 5 6 Total depreciation and amortization expense $ 750 $ 685 $ 628 Consumers Depreciation expense – plant, property, and equipment $ 586 $ 546 $ 511 Amortization expense Software 69 49 39 Other intangible assets 4 3 3 Securitized regulatory assets 83 75 63 Other regulatory assets 2 5 6 Total depreciation and amortization expense $ 744 $ 678 $ 622
Schedule of Finite-Lived Intangible Assets by Major Class Table	In Millions December 31, 2015 December 31, 2014 Description Amortization Life in Years Gross Cost 1 Accumulated Amortization Gross Cost 1 Accumulated Amortization CMS Energy, including Consumers Software development 2 - 15 $ 734 $ 294 $ 596 $ 223 Rights of way 50 - 75 153 46 150 44 Franchises and consents 5 - 30 15 8 15 8 Leasehold improvements various 2 7 5 5 4 Other intangibles various 21 15 21 14 Total $ 930 $ 368 $ 787 $ 293 Consumers Software development 3 - 15 $ 729 $ 291 $ 594 $ 221 Rights of way 50 - 75 153 46 150 44 Franchises and consents 5 - 30 15 8 15 8 Leasehold improvements various 2 7 5 5 4 Other intangibles various 21 15 21 14 Total $ 925 $ 365 $ 785 $ 291 1 Net intangible asset additions for Consumers’ utility plant were $ 140 million during 201 5 and $ 96 million during 201 4 and primarily represented software development costs. 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 $ 1,078 $ 245 $ 200 Accumulated depreciation (542) (151) (63) Construction work in progress 494 157 4 Net investment $ 1,030 $ 251 $ 141

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of Rent Expense	In Millions Years Ended December 31 2015 2014 2013 Consumers Minimum operating lease expense PPAs $ 6 $ 6 $ 6 Other agreements 19 19 21 Contingent rental expense 1 82 85 77 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 Financing 1 Operating Leases Consumers 2016 $ 14 $ 17 $ 20 2017 14 17 19 2018 13 16 16 2019 13 15 10 2020 11 14 10 2021 and thereafter 36 17 29 Total minimum lease payments $ 101 $ 96 $ 104 Less imputed interest 43 14 Present value of net minimum lease payments $ 58 $ 82 Less current portion 9 13 Non-current portion $ 49 $ 69 1 In 2007, Consumers sold Palisades to Entergy and entered into a 15 -year PPA to buy all of the capacity and energy then capable of being produced by Palisades. Consumers has continuing involvement with Palisades through security provided to Entergy for Consumers’ PPA obligation and other arrangements. Because of these ongoing arrangements, Consumers accounted for the transaction as a financing of Palisades and not a sale. Accordingly, no gain on the sale of Palisades was recognized on the consolidated statements of income. Consumers accounted for the remaining non-real-estate assets and liabilities associated with the transaction as a sale. Palisades remains on Consumers’ consolidated balance sheets and Consumers continues to depreciate it. Consumers recorded the related proceeds as a financing obligation with payments recorded to interest expense and the financing obligation based on the amortization of the obligation over the life of the Palisades PPA. The value of the financing obligation was determined based on an allocation of the transaction proceeds to the fair values of the net assets sold and fair value of the plant asset under the financing. Total amortization and interest charges under the financing were $18 million for the year ended December 31, 2015 , $19 million for the year ended December 31, 2014 , and $20 million for the year ended December 31, 2013 .
Consumers Energy Company [Member]
Schedule of Rent Expense	In Millions Years Ended December 31 2015 2014 2013 Consumers Minimum operating lease expense PPAs $ 6 $ 6 $ 6 Other agreements 19 19 21 Contingent rental expense 1 82 85 77 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 Financing 1 Operating Leases Consumers 2016 $ 14 $ 17 $ 20 2017 14 17 19 2018 13 16 16 2019 13 15 10 2020 11 14 10 2021 and thereafter 36 17 29 Total minimum lease payments $ 101 $ 96 $ 104 Less imputed interest 43 14 Present value of net minimum lease payments $ 58 $ 82 Less current portion 9 13 Non-current portion $ 49 $ 69 1 In 2007, Consumers sold Palisades to Entergy and entered into a 15 -year PPA to buy all of the capacity and energy then capable of being produced by Palisades. Consumers has continuing involvement with Palisades through security provided to Entergy for Consumers’ PPA obligation and other arrangements. Because of these ongoing arrangements, Consumers accounted for the transaction as a financing of Palisades and not a sale. Accordingly, no gain on the sale of Palisades was recognized on the consolidated statements of income. Consumers accounted for the remaining non-real-estate assets and liabilities associated with the transaction as a sale. Palisades remains on Consumers’ consolidated balance sheets and Consumers continues to depreciate it. Consumers recorded the related proceeds as a financing obligation with payments recorded to interest expense and the financing obligation based on the amortization of the obligation over the life of the Palisades PPA. The value of the financing obligation was determined based on an allocation of the transaction proceeds to the fair values of the net assets sold and fair value of the plant asset under the financing. Total amortization and interest charges under the financing were $18 million for the year ended December 31, 2015 , $19 million for the year ended December 31, 2014 , and $20 million for the year ended December 31, 2013 .

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of Change in Asset Retirement Obligation	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 Wind parks 6 - - - - 6 Total Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438 In Millions ARO ARO Liability Cash flow Liability Company and ARO Description 12/31/2013 Incurred Settled Accretion Revisions 12/31/2014 CMS Energy, including Consumers Consumers $ 324 $ 9 $ (12) $ 18 $ - $ 339 Gas treating plant and gas wells 1 - - - - 1 Total CMS Energy $ 325 $ 9 $ (12) $ 18 $ - $ 340 Consumers Coal ash disposal areas $ 118 $ - $ (3) $ 5 $ - $ 120 Gas distribution cut, purge, and cap 154 6 (8) 10 - 162 Asbestos abatement 49 - (1) 3 - 51 Wind parks 3 3 - - - 6 Total Consumers $ 324 $ 9 $ (12) $ 18 $ - $ 339
Consumers Energy Company [Member]
Schedule of Change in Asset Retirement Obligation	In Millions ARO ARO Liability Cash flow Liability Company and ARO Description 12/31/2014 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 Wind parks 6 - - - - 6 Total Consumers $ 339 $ 11 $ (6) $ 20 $ 74 $ 438 In Millions ARO ARO Liability Cash flow Liability Company and ARO Description 12/31/2013 Incurred Settled Accretion Revisions 12/31/2014 CMS Energy, including Consumers Consumers $ 324 $ 9 $ (12) $ 18 $ - $ 339 Gas treating plant and gas wells 1 - - - - 1 Total CMS Energy $ 325 $ 9 $ (12) $ 18 $ - $ 340 Consumers Coal ash disposal areas $ 118 $ - $ (3) $ 5 $ - $ 120 Gas distribution cut, purge, and cap 154 6 (8) 10 - 162 Asbestos abatement 49 - (1) 3 - 51 Wind parks 3 3 - - - 6 Total Consumers $ 324 $ 9 $ (12) $ 18 $ - $ 339

Retirement Benefits (Tables)

Retirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Schedule Of SERP Trust Assets, ABO And Contributions	In Millions Years Ended December 31 2015 2014 CMS Energy, including Consumers Trust assets $ 148 $ 131 ABO 140 145 Contributions 25 - Consumers Trust assets $ 106 $ 93 ABO 97 99 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, 2015 Point Increase Point Decrease CMS Energy, including Consumers Effect on total service and interest cost component $ 11 $ (9) Effect on PBO 168 (137) Consumers Effect on total service and interest cost component $ 11 $ (9) Effect on PBO 164 (133)
Schedule Of Assumptions Used	December 31 2015 2014 2013 CMS Energy, including Consumers Weighted average for benefit obligations 1 Discount rate 2 DB Pension Plan 4.52 % 4.10 % 4.90 % DB SERP 4.43 4.10 4.90 OPEB Plan 4.70 4.30 5.10 Rate of compensation increase DB Pension Plan 3.00 3.00 3.00 DB SERP 5.50 5.50 5.50 Weighted average for net periodic benefit cost 1 Discount rate 2,3 DB Pension Plan 4.10 4.90 4.10 DB SERP 4.10 4.90 4.10 OPEB Plan 4.30 5.10 4.40 Expected long-term rate of return on plan assets 4 DB Pension Plan 7.50 7.50 7.75 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 2015 and 2014 for benefit obligations was based on the RP- 2014 mortality table, with projection scales MP-2015 for 2015 and MP-2014 for 2014 . The mortality assumption for 2013 was based on the RP - 2000 mortality tables with projection of future mortality improvements using Scale AA, which aligned with the IRS prescriptions for cash funding valuations under the Pension Protection Act of 2006. The mortality assumption for net periodic benefit cost for 2015 was based on the RP - 2014 mortality table with projection scale MP-2014, and for 2014 and 2013 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 in which they determine the discount rate used to calculate the service cost and interest expense 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 expense; 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. CMS Energy and Consumers expect that this change will result in a decrease in the service cost and interest expense components of net periodic benefit costs for the DB Pension and OPEB Plans, with an offsetting impact to the actuarial gain or loss recorded in, and later amortized from, the associated regulatory asset and AOCI. This change represents a change in accounting estimate and will not impact years prior to 2016. 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 7.5 percent in 201 5 . The actual return (loss) on DB Pension Plan assets was (2.0) percent in 201 5 , 7.4 percent in 2014 , and 12.5 percent in 201 3 .
Schedule Of Net Benefit Costs	In Millions DB Pension Plan and DB SERP OPEB Plan Years Ended December 31 2015 2014 2013 2015 2014 2013 CMS Energy, including Consumers Net periodic cost (credit) Service cost $ 50 $ 42 $ 54 $ 25 $ 20 $ 29 Interest expense 108 105 100 58 56 65 Expected return on plan assets (138) (135) (127) (91) (88) (77) Amortization of: Net loss 97 60 101 21 2 26 Prior service cost (credit) 1 1 3 (41) (41) (31) Net periodic cost (credit) $ 118 $ 73 $ 131 $ (28) $ (51) $ 12 Consumers Net periodic cost (credit) Service cost $ 49 $ 41 $ 52 $ 25 $ 20 $ 28 Interest expense 103 100 96 56 54 63 Expected return on plan assets (134) (131) (124) (86) (83) (72) Amortization of: Net loss 93 59 98 22 3 27 Prior service cost (credit) 1 1 3 (40) (40) (30) Net periodic cost (credit) $ 112 $ 70 $ 125 $ (23) $ (46) $ 16
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 $ 72 $ (18) AOCI 1 (2) Consumers Regulatory asset $ 72 $ (18)
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 2015 2014 2015 2014 2015 2014 CMS Energy, including Consumers Benefit obligation at beginning of period $ 2,547 $ 2,073 $ 156 $ 132 $ 1,378 $ 1,123 Service cost 49 41 1 1 25 20 Interest cost 102 99 6 6 58 56 Plan amendments 13 - - - (25) - Actuarial (gain) loss (153) 458 1 (5) 24 (152) 230 1 Benefits paid (155) (124) (8) (7) (57) 2 (51) 2 Benefit obligation at end of period $ 2,403 $ 2,547 $ 150 $ 156 $ 1,227 $ 1,378 Plan assets at fair value at beginning of period $ 1,979 $ 1,964 $ - $ - $ 1,265 $ 1,218 Actual return on plan assets (36) 139 - - (29) 72 Company contribution 225 - 8 7 29 25 Actual benefits paid (155) (124) (8) (7) (57) 2 (50) 2 Plan assets at fair value at end of period $ 2,013 $ 1,979 $ - $ - $ 1,208 $ 1,265 Funded status $ (390) 3 $ (568) 3 $ (150) $ (156) $ (19) $ (113) Consumers Benefit obligation at beginning of period $ 111 $ 93 $ 1,336 $ 1,088 Service cost 1 1 25 20 Interest cost 4 4 56 54 Plan amendments - - (24) - Actuarial (gain) loss (5) 17 (150) 223 1 Benefits paid (5) (4) (55) 2 (49) 2 Benefit obligation at end of period $ 106 $ 111 $ 1,188 $ 1,336 Plan assets at fair value at beginning of period $ - $ - $ 1,186 $ 1,141 Actual return on plan assets - - (27) 68 Company contribution 5 4 29 25 Actual benefits paid (5) (4) (55) 2 (48) 2 Plan assets at fair value at end of period $ - $ - $ 1,133 $ 1,186 Funded status $ (106) $ (111) $ (55) $ (150) 1 The actuarial loss for 2014 was primarily the result of lowering the discount rates used in calculating the plans’ obligations and using the RP-2014 mortality table during the annual measurement of benefit obligations. 2 CMS Energy received less than $ 1 million in 2015, $4 million in 2014, and $ 5 million in 2013 for the Medicare Part D subsidies. Consumers received less than $1 million in 2015 and $ 4 million in each of 2014 and 2013 for the Medicare Part D subsidies. The Medicare Part D subsidy payments are used to pay OPEB Plan benefits. 3 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. At December 31, 2014 , $ 532 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 2015 2014 CMS Energy, including Consumers Current assets (liabilities) DB SERP $ (8) $ (8) Non-current assets (liabilities) DB Pension Plan (390) (568) DB SERP (142) (148) OPEB Plan (19) (113) Consumers Current assets (liabilities) DB SERP $ (5) $ (5) Non-current assets (liabilities) DB Pension Plan (368) (532) DB SERP (101) (106) OPEB Plan (55) (150)
Schedule Of Accumulated And Projected Benefit Obligations	In Millions December 31 2015 2014 CMS Energy, including Consumers DB Pension Plan PBO $ 2,403 $ 2,547 DB Pension Plan ABO 2,140 2,257 Fair value of DB Pension Plan assets 2,013 1,979
Schedule Of Net Periodic Benefit Cost Not Yet Recognized Including Regulatory Assets	In Millions DB Pension Plan and DB SERP OPEB Plan Years Ended December 31 2015 2014 2015 2014 CMS Energy, including Consumers Regulatory assets Net loss $ 944 $ 1,012 $ 360 $ 419 Prior service cost (credit) 19 7 (227) (243) Regulatory assets $ 963 $ 1,019 $ 133 $ 176 AOCI Net loss (gain) 86 99 (11) (18) Prior service cost (credit) 1 1 (8) (8) Total amounts recognized in regulatory assets and AOCI $ 1,050 $ 1,119 $ 114 $ 150 Consumers Regulatory assets Net loss $ 944 $ 1,012 $ 360 $ 419 Prior service cost (credit) 19 7 (227) (243) Regulatory assets $ 963 $ 1,019 $ 133 $ 176 AOCI Net loss (gain) 29 39 - - Total amounts recognized in regulatory assets and AOCI $ 992 $ 1,058 $ 133 $ 176
Schedule Of Allocation Of Plan Assets	In Millions DB Pension Plan December 31, 2015 December 31, 2014 Total Level 1 Level 2 Total Level 1 Level 2 CMS Energy, including Consumers Asset category Cash and short-term investments $ 215 $ 215 $ - $ 31 $ 31 $ - U.S. government and agencies securities 19 - 19 30 - 30 Corporate debt 243 - 243 222 - 222 State and municipal bonds 8 - 8 8 - 8 Foreign corporate bonds 16 - 16 21 - 21 Mutual funds 538 538 - 598 598 - Pooled funds 974 - 974 1,069 - 1,069 Total $ 2,013 $ 753 $ 1,260 $ 1,979 $ 629 $ 1,350 In Millions OPEB Plan December 31, 2015 December 31, 2014 Total Level 1 Level 2 Total Level 1 Level 2 CMS Energy, including Consumers Asset category Cash and short-term investments $ 51 $ 51 $ - $ 19 $ 19 $ - U.S. government and agencies securities 3 - 3 5 - 5 Corporate debt 34 - 34 33 - 33 State and municipal bonds 1 - 1 1 - 1 Foreign corporate bonds 2 - 2 3 - 3 Common stocks 54 54 - 69 69 - Mutual funds 456 456 - 438 438 - Pooled funds 607 - 607 697 - 697 Total $ 1,208 $ 561 $ 647 $ 1,265 $ 526 $ 739 Consumers Asset category Cash and short-term investments $ 48 $ 48 $ - $ 18 $ 18 $ - U.S. government and agencies securities 3 - 3 4 - 4 Corporate debt 32 - 32 31 - 31 State and municipal bonds 1 - 1 1 - 1 Foreign corporate bonds 2 - 2 3 - 3 Common stocks 51 51 - 65 65 - Mutual funds 427 427 - 411 411 - Pooled funds 569 - 569 653 - 653 Total $ 1,133 $ 526 $ 607 $ 1,186 $ 494 $ 692
Schedule Of Investment Components Of Pooled Funds	DB Pension Plan OPEB Plan December 31 2015 2014 2015 2014 U.S. equity securities 62 % 64 % 58 % 62 % Foreign equity securities 18 16 13 12 U.S. fixed-income securities 11 9 22 18 Foreign fixed-income securities 6 6 5 5 Alternative investments 3 5 2 3 100 % 100 % 100 % 100 %
Schedule Of Plan Contributions	In Millions Years Ended December 31 2015 2014 CMS Energy, including Consumers OPEB Plan VEBA trust $ 29 $ 16 401(h) component - 9 $ 29 $ 25 DB Pension Plan $ 225 $ - Consumers OPEB Plan VEBA trust $ 29 $ 16 401(h) component - 9 $ 29 $ 25 DB Pension Plan $ 209 $ -
Schedule Of Expected Benefit Payments	In Millions DB Pension Plan DB SERP OPEB Plan CMS Energy, including Consumers 2016 $ 141 $ 8 $ 53 2017 146 8 57 2018 152 8 59 2019 156 9 63 2020 159 10 65 2021-2025 815 50 353 Consumers 2016 $ 137 $ 5 $ 51 2017 142 5 55 2018 148 5 57 2019 152 5 61 2020 155 6 63 2021-2025 793 30 341
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule Of SERP Trust Assets, ABO And Contributions	In Millions Years Ended December 31 2015 2014 CMS Energy, including Consumers Trust assets $ 148 $ 131 ABO 140 145 Contributions 25 - Consumers Trust assets $ 106 $ 93 ABO 97 99 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, 2015 Point Increase Point Decrease CMS Energy, including Consumers Effect on total service and interest cost component $ 11 $ (9) Effect on PBO 168 (137) Consumers Effect on total service and interest cost component $ 11 $ (9) Effect on PBO 164 (133)
Schedule Of Assumptions Used	December 31 2015 2014 2013 CMS Energy, including Consumers Weighted average for benefit obligations 1 Discount rate 2 DB Pension Plan 4.52 % 4.10 % 4.90 % DB SERP 4.43 4.10 4.90 OPEB Plan 4.70 4.30 5.10 Rate of compensation increase DB Pension Plan 3.00 3.00 3.00 DB SERP 5.50 5.50 5.50 Weighted average for net periodic benefit cost 1 Discount rate 2,3 DB Pension Plan 4.10 4.90 4.10 DB SERP 4.10 4.90 4.10 OPEB Plan 4.30 5.10 4.40 Expected long-term rate of return on plan assets 4 DB Pension Plan 7.50 7.50 7.75 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 2015 and 2014 for benefit obligations was based on the RP- 2014 mortality table, with projection scales MP-2015 for 2015 and MP-2014 for 2014 . The mortality assumption for 2013 was based on the RP - 2000 mortality tables with projection of future mortality improvements using Scale AA, which aligned with the IRS prescriptions for cash funding valuations under the Pension Protection Act of 2006. The mortality assumption for net periodic benefit cost for 2015 was based on the RP - 2014 mortality table with projection scale MP-2014, and for 2014 and 2013 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 in which they determine the discount rate used to calculate the service cost and interest expense 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 expense; 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. CMS Energy and Consumers expect that this change will result in a decrease in the service cost and interest expense components of net periodic benefit costs for the DB Pension and OPEB Plans, with an offsetting impact to the actuarial gain or loss recorded in, and later amortized from, the associated regulatory asset and AOCI. This change represents a change in accounting estimate and will not impact years prior to 2016. 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 7.5 percent in 201 5 . The actual return (loss) on DB Pension Plan assets was (2.0) percent in 201 5 , 7.4 percent in 2014 , and 12.5 percent in 201 3 .
Schedule Of Net Benefit Costs	In Millions DB Pension Plan and DB SERP OPEB Plan Years Ended December 31 2015 2014 2013 2015 2014 2013 CMS Energy, including Consumers Net periodic cost (credit) Service cost $ 50 $ 42 $ 54 $ 25 $ 20 $ 29 Interest expense 108 105 100 58 56 65 Expected return on plan assets (138) (135) (127) (91) (88) (77) Amortization of: Net loss 97 60 101 21 2 26 Prior service cost (credit) 1 1 3 (41) (41) (31) Net periodic cost (credit) $ 118 $ 73 $ 131 $ (28) $ (51) $ 12 Consumers Net periodic cost (credit) Service cost $ 49 $ 41 $ 52 $ 25 $ 20 $ 28 Interest expense 103 100 96 56 54 63 Expected return on plan assets (134) (131) (124) (86) (83) (72) Amortization of: Net loss 93 59 98 22 3 27 Prior service cost (credit) 1 1 3 (40) (40) (30) Net periodic cost (credit) $ 112 $ 70 $ 125 $ (23) $ (46) $ 16
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 $ 72 $ (18) AOCI 1 (2) Consumers Regulatory asset $ 72 $ (18)
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 2015 2014 2015 2014 2015 2014 CMS Energy, including Consumers Benefit obligation at beginning of period $ 2,547 $ 2,073 $ 156 $ 132 $ 1,378 $ 1,123 Service cost 49 41 1 1 25 20 Interest cost 102 99 6 6 58 56 Plan amendments 13 - - - (25) - Actuarial (gain) loss (153) 458 1 (5) 24 (152) 230 1 Benefits paid (155) (124) (8) (7) (57) 2 (51) 2 Benefit obligation at end of period $ 2,403 $ 2,547 $ 150 $ 156 $ 1,227 $ 1,378 Plan assets at fair value at beginning of period $ 1,979 $ 1,964 $ - $ - $ 1,265 $ 1,218 Actual return on plan assets (36) 139 - - (29) 72 Company contribution 225 - 8 7 29 25 Actual benefits paid (155) (124) (8) (7) (57) 2 (50) 2 Plan assets at fair value at end of period $ 2,013 $ 1,979 $ - $ - $ 1,208 $ 1,265 Funded status $ (390) 3 $ (568) 3 $ (150) $ (156) $ (19) $ (113) Consumers Benefit obligation at beginning of period $ 111 $ 93 $ 1,336 $ 1,088 Service cost 1 1 25 20 Interest cost 4 4 56 54 Plan amendments - - (24) - Actuarial (gain) loss (5) 17 (150) 223 1 Benefits paid (5) (4) (55) 2 (49) 2 Benefit obligation at end of period $ 106 $ 111 $ 1,188 $ 1,336 Plan assets at fair value at beginning of period $ - $ - $ 1,186 $ 1,141 Actual return on plan assets - - (27) 68 Company contribution 5 4 29 25 Actual benefits paid (5) (4) (55) 2 (48) 2 Plan assets at fair value at end of period $ - $ - $ 1,133 $ 1,186 Funded status $ (106) $ (111) $ (55) $ (150) 1 The actuarial loss for 2014 was primarily the result of lowering the discount rates used in calculating the plans’ obligations and using the RP-2014 mortality table during the annual measurement of benefit obligations. 2 CMS Energy received less than $ 1 million in 2015, $4 million in 2014, and $ 5 million in 2013 for the Medicare Part D subsidies. Consumers received less than $1 million in 2015 and $ 4 million in each of 2014 and 2013 for the Medicare Part D subsidies. The Medicare Part D subsidy payments are used to pay OPEB Plan benefits. 3 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. At December 31, 2014 , $ 532 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 2015 2014 CMS Energy, including Consumers Current assets (liabilities) DB SERP $ (8) $ (8) Non-current assets (liabilities) DB Pension Plan (390) (568) DB SERP (142) (148) OPEB Plan (19) (113) Consumers Current assets (liabilities) DB SERP $ (5) $ (5) Non-current assets (liabilities) DB Pension Plan (368) (532) DB SERP (101) (106) OPEB Plan (55) (150)
Schedule Of Accumulated And Projected Benefit Obligations	In Millions December 31 2015 2014 CMS Energy, including Consumers DB Pension Plan PBO $ 2,403 $ 2,547 DB Pension Plan ABO 2,140 2,257 Fair value of DB Pension Plan assets 2,013 1,979
Schedule Of Net Periodic Benefit Cost Not Yet Recognized Including Regulatory Assets	In Millions DB Pension Plan and DB SERP OPEB Plan Years Ended December 31 2015 2014 2015 2014 CMS Energy, including Consumers Regulatory assets Net loss $ 944 $ 1,012 $ 360 $ 419 Prior service cost (credit) 19 7 (227) (243) Regulatory assets $ 963 $ 1,019 $ 133 $ 176 AOCI Net loss (gain) 86 99 (11) (18) Prior service cost (credit) 1 1 (8) (8) Total amounts recognized in regulatory assets and AOCI $ 1,050 $ 1,119 $ 114 $ 150 Consumers Regulatory assets Net loss $ 944 $ 1,012 $ 360 $ 419 Prior service cost (credit) 19 7 (227) (243) Regulatory assets $ 963 $ 1,019 $ 133 $ 176 AOCI Net loss (gain) 29 39 - - Total amounts recognized in regulatory assets and AOCI $ 992 $ 1,058 $ 133 $ 176
Schedule Of Allocation Of Plan Assets	In Millions DB Pension Plan December 31, 2015 December 31, 2014 Total Level 1 Level 2 Total Level 1 Level 2 CMS Energy, including Consumers Asset category Cash and short-term investments $ 215 $ 215 $ - $ 31 $ 31 $ - U.S. government and agencies securities 19 - 19 30 - 30 Corporate debt 243 - 243 222 - 222 State and municipal bonds 8 - 8 8 - 8 Foreign corporate bonds 16 - 16 21 - 21 Mutual funds 538 538 - 598 598 - Pooled funds 974 - 974 1,069 - 1,069 Total $ 2,013 $ 753 $ 1,260 $ 1,979 $ 629 $ 1,350 In Millions OPEB Plan December 31, 2015 December 31, 2014 Total Level 1 Level 2 Total Level 1 Level 2 CMS Energy, including Consumers Asset category Cash and short-term investments $ 51 $ 51 $ - $ 19 $ 19 $ - U.S. government and agencies securities 3 - 3 5 - 5 Corporate debt 34 - 34 33 - 33 State and municipal bonds 1 - 1 1 - 1 Foreign corporate bonds 2 - 2 3 - 3 Common stocks 54 54 - 69 69 - Mutual funds 456 456 - 438 438 - Pooled funds 607 - 607 697 - 697 Total $ 1,208 $ 561 $ 647 $ 1,265 $ 526 $ 739 Consumers Asset category Cash and short-term investments $ 48 $ 48 $ - $ 18 $ 18 $ - U.S. government and agencies securities 3 - 3 4 - 4 Corporate debt 32 - 32 31 - 31 State and municipal bonds 1 - 1 1 - 1 Foreign corporate bonds 2 - 2 3 - 3 Common stocks 51 51 - 65 65 - Mutual funds 427 427 - 411 411 - Pooled funds 569 - 569 653 - 653 Total $ 1,133 $ 526 $ 607 $ 1,186 $ 494 $ 692
Schedule Of Investment Components Of Pooled Funds	DB Pension Plan OPEB Plan December 31 2015 2014 2015 2014 U.S. equity securities 62 % 64 % 58 % 62 % Foreign equity securities 18 16 13 12 U.S. fixed-income securities 11 9 22 18 Foreign fixed-income securities 6 6 5 5 Alternative investments 3 5 2 3 100 % 100 % 100 % 100 %
Schedule Of Plan Contributions	In Millions Years Ended December 31 2015 2014 CMS Energy, including Consumers OPEB Plan VEBA trust $ 29 $ 16 401(h) component - 9 $ 29 $ 25 DB Pension Plan $ 225 $ - Consumers OPEB Plan VEBA trust $ 29 $ 16 401(h) component - 9 $ 29 $ 25 DB Pension Plan $ 209 $ -
Schedule Of Expected Benefit Payments	In Millions DB Pension Plan DB SERP OPEB Plan CMS Energy, including Consumers 2016 $ 141 $ 8 $ 53 2017 146 8 57 2018 152 8 59 2019 156 9 63 2020 159 10 65 2021-2025 815 50 353 Consumers 2016 $ 137 $ 5 $ 51 2017 142 5 55 2018 148 5 57 2019 152 5 61 2020 155 6 63 2021-2025 793 30 341

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule Of Restricted Stock Activity	CMS Energy, including Consumers Consumers Year Ended December 31, 2015 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 1,679,595 $ 24.69 1,614,684 $ 24.71 Granted Restricted stock 789,602 36.84 750,262 36.83 Restricted stock units 13,180 34.25 12,837 34.25 Vested - restricted stock (793,103) 27.76 (756,286) 27.74 Forfeited - restricted stock (64,340) 26.93 (63,840) 26.93 Nonvested at end of period 1,624,934 $ 29.08 1,557,657 $ 29.06 Year Ended December 31, 2015 CMS Energy, including Consumers Consumers Granted Time-lapse awards 152,820 146,536 Market-based awards 158,385 149,909 Performance-based awards 158,385 149,909 Restricted stock units 12,848 12,514 Dividends on market-based awards 22,208 21,129 Dividends on performance-based awards 11,046 10,502 Dividends on restricted stock units 332 323 Additional market-based shares based on achievement of condition 286,758 272,277 Total granted 802,782 763,099
Schedule of Share-based Payment Award, Restricted Stock, Valuation Assumptions	Years Ended December 31 2015 2014 2013 Expected volatility 14.1 % 15.6 % 17.4 % Expected dividend yield 3.3 3.7 3.9 Risk-free rate 0.8 0.8 0.4
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Weighted-average grant-date fair value per share Restricted stock granted $ 36.84 $ 26.15 $ 16.65 Restricted stock units granted 34.25 - - Consumers Weighted-average grant-date fair value per share Restricted stock granted $ 36.83 $ 26.18 $ 16.76 Restricted stock units granted 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 2015 2014 2013 CMS Energy, including Consumers Fair value of shares that vested during the year $ 29 $ 16 $ 10 Compensation expense recognized 20 14 14 Income tax benefit recognized 8 5 5 Consumers Fair value of shares that vested during the year $ 28 $ 15 $ 9 Compensation expense recognized 19 13 14 Income tax benefit recognized 7 5 5
Consumers Energy Company [Member]
Schedule Of Restricted Stock Activity	CMS Energy, including Consumers Consumers Year Ended December 31, 2015 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 1,679,595 $ 24.69 1,614,684 $ 24.71 Granted Restricted stock 789,602 36.84 750,262 36.83 Restricted stock units 13,180 34.25 12,837 34.25 Vested - restricted stock (793,103) 27.76 (756,286) 27.74 Forfeited - restricted stock (64,340) 26.93 (63,840) 26.93 Nonvested at end of period 1,624,934 $ 29.08 1,557,657 $ 29.06 Year Ended December 31, 2015 CMS Energy, including Consumers Consumers Granted Time-lapse awards 152,820 146,536 Market-based awards 158,385 149,909 Performance-based awards 158,385 149,909 Restricted stock units 12,848 12,514 Dividends on market-based awards 22,208 21,129 Dividends on performance-based awards 11,046 10,502 Dividends on restricted stock units 332 323 Additional market-based shares based on achievement of condition 286,758 272,277 Total granted 802,782 763,099
Schedule of Share-based Payment Award, Restricted Stock, Valuation Assumptions	Years Ended December 31 2015 2014 2013 Expected volatility 14.1 % 15.6 % 17.4 % Expected dividend yield 3.3 3.7 3.9 Risk-free rate 0.8 0.8 0.4
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Weighted-average grant-date fair value per share Restricted stock granted $ 36.84 $ 26.15 $ 16.65 Restricted stock units granted 34.25 - - Consumers Weighted-average grant-date fair value per share Restricted stock granted $ 36.83 $ 26.18 $ 16.76 Restricted stock units granted 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 2015 2014 2013 CMS Energy, including Consumers Fair value of shares that vested during the year $ 29 $ 16 $ 10 Compensation expense recognized 20 14 14 Income tax benefit recognized 8 5 5 Consumers Fair value of shares that vested during the year $ 28 $ 15 $ 9 Compensation expense recognized 19 13 14 Income tax benefit recognized 7 5 5

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule Of Effective Income Tax Rate Reconciliation	In Millions, Except Tax Rate Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Income from continuing operations before income taxes $ 796 $ 729 $ 756 Income tax expense at statutory rate 279 255 265 Increase (decrease) in income taxes from: State and local income taxes, net of federal effect 39 36 37 Accelerated flow-through of regulatory tax benefits (39) (39) - Other, net (8) (2) - Income tax expense $ 271 $ 250 $ 302 Effective tax rate 34.0 % 34.3 % 39.9 % Consumers Income from continuing operations before income taxes $ 896 $ 873 $ 880 Income tax expense at statutory rate 314 306 308 Increase (decrease) in income taxes from: State and local income taxes, net of federal effect 42 42 43 Accelerated flow-through of regulatory tax benefits (39) (39) - Other, net (15) (3) (5) Income tax expense $ 302 $ 306 $ 346 Effective tax rate 33.7 % 35.1 % 39.3 %
Significant Components Of Income Tax Expense Table	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Current income taxes Federal $ - $ - $ - State and local 24 24 34 $ 24 $ 24 $ 34 Deferred income taxes Federal $ 192 $ 198 $ 248 State and local 36 31 23 $ 228 $ 229 $ 271 Deferred income tax credit 19 (3) (3) Tax expense $ 271 $ 250 $ 302 Consumers Current income taxes Federal $ 66 $ 8 $ 137 State and local 32 36 45 $ 98 $ 44 $ 182 Deferred income taxes Federal $ 153 $ 236 $ 147 State and local 32 29 20 $ 185 $ 265 $ 167 Deferred income tax credit 19 (3) (3) Tax expense $ 302 $ 306 $ 346
Principal Components Of Deferred Income Tax Assets Table	In Millions December 31 2015 2014 CMS Energy, including Consumers Employee benefits $ (127) $ (72) Gas inventory (96) (117) Plant, property, and equipment (2,429) (2,217) Net regulatory tax liability 50 65 Reserves and accruals 59 63 Securitized costs (122) (144) Tax loss and credit carryforwards 657 676 Other (5) - $ (2,013) $ (1,746) Less valuation allowance (4) (2) Total net deferred income tax liabilities $ (2,017) $ (1,748) Deferred tax assets, net of valuation reserves $ 762 $ 802 Deferred tax liabilities (2,779) (2,550) Total net deferred income tax liabilities $ (2,017) $ (1,748) Consumers Employee benefits $ (156) $ (103) Gas inventory (96) (117) Plant, property, and equipment (2,457) (2,263) Net regulatory tax liability 50 65 Reserves and accruals 30 34 Securitized costs (122) (144) Tax loss and credit carryforwards 46 45 Other (5) (2) $ (2,710) $ (2,485) Less valuation allowance - (1) Total net deferred income tax liabilities $ (2,710) $ (2,486) Deferred tax assets, net of valuation reserves $ 126 $ 143 Deferred tax liabilities (2,836) (2,629) Total net deferred income tax liabilities $ (2,710) $ (2,486)
Loss And Credit Carryforwards Table	In Millions Gross Amount Tax Attribute Expiration CMS Energy, including Consumers Federal net operating loss carryforward $ 885 $ 311 2025 – 2034 Local net operating loss carryforwards 414 4 2023 – 2034 Alternative minimum tax credits 270 270 No expiration Charitable contribution carryover 2 1 2016 – 2019 General business credits 71 71 2018 – 2035 Total tax attributes $ 657 Consumers Federal net operating loss carryforward $ 121 $ 42 2025 – 2034 Charitable contribution carryover 2 1 2016 – 2019 General business credits 3 3 2032 – 2035 Total tax attributes $ 46
Reconciliation Of Beginning And Ending Uncertain Tax Benefits Table	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Balance at beginning of period $ 5 $ 4 $ 1 Additions for current-year tax positions 1 2 - Additions for prior-year tax positions 1 1 3 Reductions for prior-year tax positions (1) (2) - Balance at end of period $ 6 $ 5 $ 4 Consumers Balance at beginning of period $ 5 $ 4 $ 1 Additions for current-year tax positions 1 2 - Additions for prior-year tax positions 1 1 3 Reductions for prior-year tax positions (1) (2) - Balance at end of period $ 6 $ 5 $ 4
Consumers Energy Company [Member]
Schedule Of Effective Income Tax Rate Reconciliation	In Millions, Except Tax Rate Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Income from continuing operations before income taxes $ 796 $ 729 $ 756 Income tax expense at statutory rate 279 255 265 Increase (decrease) in income taxes from: State and local income taxes, net of federal effect 39 36 37 Accelerated flow-through of regulatory tax benefits (39) (39) - Other, net (8) (2) - Income tax expense $ 271 $ 250 $ 302 Effective tax rate 34.0 % 34.3 % 39.9 % Consumers Income from continuing operations before income taxes $ 896 $ 873 $ 880 Income tax expense at statutory rate 314 306 308 Increase (decrease) in income taxes from: State and local income taxes, net of federal effect 42 42 43 Accelerated flow-through of regulatory tax benefits (39) (39) - Other, net (15) (3) (5) Income tax expense $ 302 $ 306 $ 346 Effective tax rate 33.7 % 35.1 % 39.3 %
Significant Components Of Income Tax Expense Table	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Current income taxes Federal $ - $ - $ - State and local 24 24 34 $ 24 $ 24 $ 34 Deferred income taxes Federal $ 192 $ 198 $ 248 State and local 36 31 23 $ 228 $ 229 $ 271 Deferred income tax credit 19 (3) (3) Tax expense $ 271 $ 250 $ 302 Consumers Current income taxes Federal $ 66 $ 8 $ 137 State and local 32 36 45 $ 98 $ 44 $ 182 Deferred income taxes Federal $ 153 $ 236 $ 147 State and local 32 29 20 $ 185 $ 265 $ 167 Deferred income tax credit 19 (3) (3) Tax expense $ 302 $ 306 $ 346
Principal Components Of Deferred Income Tax Assets Table	In Millions December 31 2015 2014 CMS Energy, including Consumers Employee benefits $ (127) $ (72) Gas inventory (96) (117) Plant, property, and equipment (2,429) (2,217) Net regulatory tax liability 50 65 Reserves and accruals 59 63 Securitized costs (122) (144) Tax loss and credit carryforwards 657 676 Other (5) - $ (2,013) $ (1,746) Less valuation allowance (4) (2) Total net deferred income tax liabilities $ (2,017) $ (1,748) Deferred tax assets, net of valuation reserves $ 762 $ 802 Deferred tax liabilities (2,779) (2,550) Total net deferred income tax liabilities $ (2,017) $ (1,748) Consumers Employee benefits $ (156) $ (103) Gas inventory (96) (117) Plant, property, and equipment (2,457) (2,263) Net regulatory tax liability 50 65 Reserves and accruals 30 34 Securitized costs (122) (144) Tax loss and credit carryforwards 46 45 Other (5) (2) $ (2,710) $ (2,485) Less valuation allowance - (1) Total net deferred income tax liabilities $ (2,710) $ (2,486) Deferred tax assets, net of valuation reserves $ 126 $ 143 Deferred tax liabilities (2,836) (2,629) Total net deferred income tax liabilities $ (2,710) $ (2,486)
Loss And Credit Carryforwards Table	In Millions Gross Amount Tax Attribute Expiration CMS Energy, including Consumers Federal net operating loss carryforward $ 885 $ 311 2025 – 2034 Local net operating loss carryforwards 414 4 2023 – 2034 Alternative minimum tax credits 270 270 No expiration Charitable contribution carryover 2 1 2016 – 2019 General business credits 71 71 2018 – 2035 Total tax attributes $ 657 Consumers Federal net operating loss carryforward $ 121 $ 42 2025 – 2034 Charitable contribution carryover 2 1 2016 – 2019 General business credits 3 3 2032 – 2035 Total tax attributes $ 46
Reconciliation Of Beginning And Ending Uncertain Tax Benefits Table	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Balance at beginning of period $ 5 $ 4 $ 1 Additions for current-year tax positions 1 2 - Additions for prior-year tax positions 1 1 3 Reductions for prior-year tax positions (1) (2) - Balance at end of period $ 6 $ 5 $ 4 Consumers Balance at beginning of period $ 5 $ 4 $ 1 Additions for current-year tax positions 1 2 - Additions for prior-year tax positions 1 1 3 Reductions for prior-year tax positions (1) (2) - Balance at end of period $ 6 $ 5 $ 4

Earnings Per Share - CMS Ener46

Earnings Per Share - CMS Energy (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share - CMS Energy [Abstract]
Basic And Diluted EPS Computations	In Millions, Except Per Share Amounts Years Ended December 31 2015 2014 2013 Income available to common stockholders Net income $ 525 $ 479 $ 454 Less income attributable to noncontrolling interests 2 2 2 Net income available to common stockholders – basic and diluted $ 523 $ 477 $ 452 Average common shares outstanding Weighted-average shares – basic 275.6 270.6 264.5 Add dilutive contingently convertible securities - 3.1 6.4 Add dilutive nonvested stock awards 0.9 0.9 1.0 Weighted-average shares – diluted 276.5 274.6 271.9 Net income per average common share available to common stockholders Basic $ 1.90 $ 1.76 $ 1.71 Diluted 1.89 1.74 1.66 Dividends declared per common share $ 1.16 $ 1.08 $ 1.02

Other Income and Other Expense

Other Income and Other Expense (Tables)	12 Months Ended
	Dec. 31, 2015
Components Of Other Income And Other Expense	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Other income Fee income $ 9 $ 8 $ 7 All other 1 3 3 Total other income – CMS Energy $ 10 $ 11 $ 10 Consumers Other income Fee income $ 9 $ 8 $ 7 Gain on CMS Energy common stock 9 - 4 All other 1 2 3 Total other income – Consumers $ 19 $ 10 $ 14 CMS Energy, including Consumers Other expense Civic and political expenditures $ (10) $ (14) $ (5) Donations (1) (15) (4) Loss on reacquired and extinguished debt - (20) (4) All other (6) (6) (7) Total other expense – CMS Energy $ (17) $ (55) $ (20) Consumers Other expense Civic and political expenditures $ (10) $ (14) $ (5) Donations (1) (15) (4) All other (6) (6) (7) Total other expense – Consumers $ (17) $ (35) $ (16)
Consumers Energy Company [Member]
Components Of Other Income And Other Expense	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Other income Fee income $ 9 $ 8 $ 7 All other 1 3 3 Total other income – CMS Energy $ 10 $ 11 $ 10 Consumers Other income Fee income $ 9 $ 8 $ 7 Gain on CMS Energy common stock 9 - 4 All other 1 2 3 Total other income – Consumers $ 19 $ 10 $ 14 CMS Energy, including Consumers Other expense Civic and political expenditures $ (10) $ (14) $ (5) Donations (1) (15) (4) Loss on reacquired and extinguished debt - (20) (4) All other (6) (6) (7) Total other expense – CMS Energy $ (17) $ (55) $ (20) Consumers Other expense Civic and political expenditures $ (10) $ (14) $ (5) Donations (1) (15) (4) All other (6) (6) (7) Total other expense – Consumers $ (17) $ (35) $ (16)

Reportable Segments (Tables)

Reportable Segments (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule Of Financial Information By Reportable Segments	In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Operating revenue Electric utility $ 4,249 $ 4,436 $ 4,173 Gas utility 1,916 2,363 2,148 Enterprises 190 299 181 Other reconciling items 101 81 64 Total operating revenue – CMS Energy $ 6,456 $ 7,179 $ 6,566 Consumers Operating revenue Electric utility $ 4,249 $ 4,436 $ 4,173 Gas utility 1,916 2,363 2,148 Other reconciling items - 1 - Total operating revenue – Consumers $ 6,165 $ 6,800 $ 6,321 CMS Energy, including Consumers Depreciation and amortization Electric utility $ 567 $ 522 $ 484 Gas utility 177 156 138 Enterprises 4 4 3 Other reconciling items 2 3 3 Total depreciation and amortization – CMS Energy $ 750 $ 685 $ 628 Consumers Depreciation and amortization Electric utility $ 567 $ 522 $ 484 Gas utility 177 156 138 Total depreciation and amortization – Consumers $ 744 $ 678 $ 622 CMS Energy, including Consumers Income from equity method investees 1 Enterprises $ 14 $ 15 $ 13 Total income from equity method investees – CMS Energy $ 14 $ 15 $ 13 CMS Energy, including Consumers Interest charges Electric utility $ 178 $ 181 $ 179 Gas utility 71 67 64 Other reconciling items 147 159 155 Total interest charges – CMS Energy $ 396 $ 407 $ 398 Consumers Interest charges Electric utility $ 178 $ 181 $ 179 Gas utility 71 67 64 Other reconciling items 1 2 2 Total interest charges – Consumers $ 250 $ 250 $ 245 In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Income tax expense (benefit) Electric utility $ 224 $ 211 $ 242 Gas utility 78 95 104 Enterprises 3 (1) (4) Other reconciling items (34) (55) (40) Total income tax expense – CMS Energy $ 271 $ 250 $ 302 Consumers Income tax expense Electric utility $ 224 $ 211 $ 242 Gas utility 78 95 104 Total income tax expense – Consumers $ 302 $ 306 $ 346 CMS Energy, including Consumers Net income (loss) available to common stockholders Electric utility $ 437 $ 384 $ 363 Gas utility 154 179 168 Enterprises 4 (1) 2 Other reconciling items (72) (85) (81) Total net income available to common stockholders – CMS Energy $ 523 $ 477 $ 452 Consumers Net income available to common stockholder Electric utility $ 437 $ 384 $ 363 Gas utility 154 179 168 Other reconciling items 1 2 1 Total net income available to common stockholder – Consumers $ 592 $ 565 $ 532 CMS Energy, including Consumers Plant, property, and equipment, gross Electric utility $ 13,059 $ 12,230 $ 11,186 Gas utility 5,723 5,335 4,843 Enterprises 120 115 115 Other reconciling items 41 41 40 Total plant, property, and equipment, gross – CMS Energy $ 18,943 $ 17,721 $ 16,184 Consumers Plant, property, and equipment, gross Electric utility $ 13,059 $ 12,230 $ 11,186 Gas utility 5,723 5,335 4,843 Other reconciling items 15 15 15 Total plant, property, and equipment, gross – Consumers $ 18,797 $ 17,580 $ 16,044 CMS Energy, including Consumers Investments in equity method investees 1 Enterprises $ 61 $ 58 $ 57 Other reconciling items 3 3 2 Total investments in equity method investees – CMS Energy $ 64 $ 61 $ 59 In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Total assets Electric utility 2 $ 12,676 $ 11,582 $ 10,487 Gas utility 2 5,918 5,391 4,784 Enterprises 270 231 231 Other reconciling items 1,476 1,981 1,788 Total assets – CMS Energy $ 20,340 $ 19,185 $ 17,290 Consumers Total assets Electric utility 2 $ 12,676 $ 11,582 $ 10,487 Gas utility 2 5,918 5,391 4,784 Other reconciling items 64 874 908 Total assets – Consumers $ 18,658 $ 17,847 $ 16,179 CMS Energy, including Consumers Capital expenditures 3 Electric utility $ 1,136 $ 1,139 $ 996 Gas utility 558 473 407 Enterprises 44 3 1 Other reconciling items 3 1 4 Total capital expenditures – CMS Energy $ 1,741 $ 1,616 $ 1,408 Consumers Capital expenditures 3 Electric utility $ 1,136 $ 1,139 $ 996 Gas utility 558 473 407 Total capital expenditures – Consumers $ 1,694 $ 1,612 $ 1,403 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 2015 2014 2013 CMS Energy, including Consumers Operating revenue Electric utility $ 4,249 $ 4,436 $ 4,173 Gas utility 1,916 2,363 2,148 Enterprises 190 299 181 Other reconciling items 101 81 64 Total operating revenue – CMS Energy $ 6,456 $ 7,179 $ 6,566 Consumers Operating revenue Electric utility $ 4,249 $ 4,436 $ 4,173 Gas utility 1,916 2,363 2,148 Other reconciling items - 1 - Total operating revenue – Consumers $ 6,165 $ 6,800 $ 6,321 CMS Energy, including Consumers Depreciation and amortization Electric utility $ 567 $ 522 $ 484 Gas utility 177 156 138 Enterprises 4 4 3 Other reconciling items 2 3 3 Total depreciation and amortization – CMS Energy $ 750 $ 685 $ 628 Consumers Depreciation and amortization Electric utility $ 567 $ 522 $ 484 Gas utility 177 156 138 Total depreciation and amortization – Consumers $ 744 $ 678 $ 622 CMS Energy, including Consumers Income from equity method investees 1 Enterprises $ 14 $ 15 $ 13 Total income from equity method investees – CMS Energy $ 14 $ 15 $ 13 CMS Energy, including Consumers Interest charges Electric utility $ 178 $ 181 $ 179 Gas utility 71 67 64 Other reconciling items 147 159 155 Total interest charges – CMS Energy $ 396 $ 407 $ 398 Consumers Interest charges Electric utility $ 178 $ 181 $ 179 Gas utility 71 67 64 Other reconciling items 1 2 2 Total interest charges – Consumers $ 250 $ 250 $ 245 In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Income tax expense (benefit) Electric utility $ 224 $ 211 $ 242 Gas utility 78 95 104 Enterprises 3 (1) (4) Other reconciling items (34) (55) (40) Total income tax expense – CMS Energy $ 271 $ 250 $ 302 Consumers Income tax expense Electric utility $ 224 $ 211 $ 242 Gas utility 78 95 104 Total income tax expense – Consumers $ 302 $ 306 $ 346 CMS Energy, including Consumers Net income (loss) available to common stockholders Electric utility $ 437 $ 384 $ 363 Gas utility 154 179 168 Enterprises 4 (1) 2 Other reconciling items (72) (85) (81) Total net income available to common stockholders – CMS Energy $ 523 $ 477 $ 452 Consumers Net income available to common stockholder Electric utility $ 437 $ 384 $ 363 Gas utility 154 179 168 Other reconciling items 1 2 1 Total net income available to common stockholder – Consumers $ 592 $ 565 $ 532 CMS Energy, including Consumers Plant, property, and equipment, gross Electric utility $ 13,059 $ 12,230 $ 11,186 Gas utility 5,723 5,335 4,843 Enterprises 120 115 115 Other reconciling items 41 41 40 Total plant, property, and equipment, gross – CMS Energy $ 18,943 $ 17,721 $ 16,184 Consumers Plant, property, and equipment, gross Electric utility $ 13,059 $ 12,230 $ 11,186 Gas utility 5,723 5,335 4,843 Other reconciling items 15 15 15 Total plant, property, and equipment, gross – Consumers $ 18,797 $ 17,580 $ 16,044 CMS Energy, including Consumers Investments in equity method investees 1 Enterprises $ 61 $ 58 $ 57 Other reconciling items 3 3 2 Total investments in equity method investees – CMS Energy $ 64 $ 61 $ 59 In Millions Years Ended December 31 2015 2014 2013 CMS Energy, including Consumers Total assets Electric utility 2 $ 12,676 $ 11,582 $ 10,487 Gas utility 2 5,918 5,391 4,784 Enterprises 270 231 231 Other reconciling items 1,476 1,981 1,788 Total assets – CMS Energy $ 20,340 $ 19,185 $ 17,290 Consumers Total assets Electric utility 2 $ 12,676 $ 11,582 $ 10,487 Gas utility 2 5,918 5,391 4,784 Other reconciling items 64 874 908 Total assets – Consumers $ 18,658 $ 17,847 $ 16,179 CMS Energy, including Consumers Capital expenditures 3 Electric utility $ 1,136 $ 1,139 $ 996 Gas utility 558 473 407 Enterprises 44 3 1 Other reconciling items 3 1 4 Total capital expenditures – CMS Energy $ 1,741 $ 1,616 $ 1,408 Consumers Capital expenditures 3 Electric utility $ 1,136 $ 1,139 $ 996 Gas utility 558 473 407 Total capital expenditures – Consumers $ 1,694 $ 1,612 $ 1,403 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 - 49

Related Party Transactions - Consumers (Tables)	12 Months Ended
	Dec. 31, 2015
Consumers Energy Company [Member]
Schedule of Related Party Transactions, by Related Party Table	In Millions Description Related Party 2015 2014 2013 Purchases of capacity and energy Affiliates of CMS Enterprises $ 83 $ 89 $ 89

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2015
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 Non-recourse long-term debt that matured in December 2007. Grayling ( 50% ) Wood waste-fueled power generator Sale of revenue bonds that were retired in March 2012. 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.

Quarterly Financial And Commo51

Quarterly Financial And Common Stock Information (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of Quarterly Financial Information Table	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 In Millions, Except Per Share Amounts and Stock Prices 2014 Quarters Ended March 31 June 30 Sept 30 Dec 31 CMS Energy, including Consumers Operating revenue $ 2,523 $ 1,468 $ 1,430 $ 1,758 Operating income 408 235 236 273 Net income 204 84 94 97 Income attributable to noncontrolling interests - 1 - 1 Net income available to common stockholders 204 83 94 96 Basic earnings per average common share 1 0.77 0.31 0.34 0.35 Diluted earnings per average common share 1 0.75 0.30 0.34 0.35 Common stock prices 2 High 29.28 31.15 30.87 36.42 Low 26.12 28.87 28.18 29.78 Consumers Operating revenue $ 2,382 $ 1,387 $ 1,359 $ 1,672 Operating income 399 227 245 264 Net income 221 109 119 118 Preferred stock dividends - 1 - 1 Net income available to common stockholder 221 108 119 117 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 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 In Millions, Except Per Share Amounts and Stock Prices 2014 Quarters Ended March 31 June 30 Sept 30 Dec 31 CMS Energy, including Consumers Operating revenue $ 2,523 $ 1,468 $ 1,430 $ 1,758 Operating income 408 235 236 273 Net income 204 84 94 97 Income attributable to noncontrolling interests - 1 - 1 Net income available to common stockholders 204 83 94 96 Basic earnings per average common share 1 0.77 0.31 0.34 0.35 Diluted earnings per average common share 1 0.75 0.30 0.34 0.35 Common stock prices 2 High 29.28 31.15 30.87 36.42 Low 26.12 28.87 28.18 29.78 Consumers Operating revenue $ 2,382 $ 1,387 $ 1,359 $ 1,672 Operating income 399 227 245 264 Net income 221 109 119 118 Preferred stock dividends - 1 - 1 Net income available to common stockholder 221 108 119 117 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 Polici52

Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
EnerBank [Member]
Significant Accounting Policies [Line Items]
Unearned income	$ 82	$ 62
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, 2015	Dec. 31, 2014	Dec. 31, 2013
Unamortized debt issuance costs	$ 41
Current deferred tax liabilities		$ 66
Unrealized gain (loss) on investments, net of tax	3	1	$ 2
Consumers Energy Company [Member]
Unamortized debt issuance costs	23
Current deferred tax liabilities		80
Unrealized gain (loss) on investments, net of tax	$ 1	$ (4)	$ (1)

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) $ in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2016USD ($)	Dec. 31, 2015USD ($)site	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Sep. 30, 2015USD ($)	Nov. 30, 2014USD ($)
Public Utilities, General Disclosures [Line Items]
Proceeds from government grant				$ 69
Accrued rate refunds		$ 26	$ 6
Cost of gas sold		961	1,493	1,228
Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Income tax benefits returned to customers		$ 64
Proceeds from government grant				69
Number of units planned to be retired | site		10
Accrued rate refunds		$ 26	6
Cost of gas sold		$ 939	1,375	1,187
Coal-Fueled Electric Generation [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Number of units planned to be 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
Electric Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested			$ 163
Rate of return on equity requested			10.70%
Annual rate increase self-implemented		$ 110
Annual rate increase authorized		$ 165
Rate of return on equity authorized		10.30%
Depreciation Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested			$ 28
Annual rate increase authorized		$ 6
Gas Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Annual rate increase requested			88
Annual rate increase authorized		$ 45
Rate of return on equity authorized		10.30%
Gas Cost Recover (GCR) [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Over (under) recovery requested		$ 9	(84)
Accrued rate refunds		18
Cost of gas sold		800	900
Power Supply Cost Recover (PSCR) [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Over (under) recovery requested		6	10
Accrued rate refunds		8
PSCR Cost of Power Sold		2,100	$ 1,900
Energy Optimization [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Authorized recovery/collection					$ 17
Requested recovery/collection		$ 18
Major Maintenance [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Authorized recovery, collection period		6 months
Authorized recovery/collection						$ 10
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
Gas Storage Inventory Adjustments [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Authorized recovery, collection period		5 years
Scenario, Forecast [Member] | Electric Rate Case [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Change in annual rate increase authorized	$ 39
Annual rate increase authorized	$ 126
Renewable Energy Grant [Member] | Consumers Energy Company [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from government grant				$ 69

Regulatory Matters (Schedule Of

Regulatory Matters (Schedule Of The Components Of Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Regulatory Matters [Line Items]
Regulatory assets, current		$ 16	$ 89
Regulatory assets, noncurrent		1,840	1,956
Regulatory liabilities, current		82	67
Regulatory liabilities, noncurrent		2,088	2,095
Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory assets, current		16	89
Regulatory assets, noncurrent		1,840	1,956
Total regulatory asset		1,856	2,045
Regulatory liabilities, current		82	67
Regulatory liabilities, noncurrent		2,088	2,095
Total regulatory liabilities		2,170	2,162
Cost Of Removal [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory liabilities, noncurrent		$ 1,745	1,673
Renewable Energy Plan [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Noncurrent Regulatory Liability, Recovery End Date		2,028
Regulatory liabilities, noncurrent		$ 109	131
Income Taxes, Net [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Current Regulatory Liability Recovery End Date		2,016
Regulatory liabilities, current		$ 64	64
Regulatory liabilities, noncurrent		64	103
ARO [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory liabilities, noncurrent		$ 73	83
Renewable Energy Grant [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Noncurrent Regulatory Liability, Recovery End Date		2,043
Regulatory liabilities, noncurrent		$ 60	63
Energy Optimization Plan [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory liabilities, noncurrent		$ 26	32
Other Regulatory Assets [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Current Regulatory Liability Recovery End Date		2,016
Regulatory liabilities, current		$ 4	3
Regulatory liabilities, noncurrent		11	10
Postretirement Benefits [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory assets, noncurrent	[1]	$ 1,096	1,195
Securitized Costs [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory Current Asset, End Date for Recovery	[2]	2,015
Current Regulatory Liability Recovery End Date		2,016
Regulatory assets, current	[2]		61
Regulatory liabilities, current		$ 14
Costs Of Electric Generating Units To Be Retired And Securitized [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Noncurrent Regulatory Asset Recovery End Date	[2]	2,029
Regulatory assets, noncurrent	[2]	$ 348	370
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory assets, noncurrent	[3]	146	147
ARO [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory assets, noncurrent	[3]	151	139
Unamortized Debt Costs [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory assets, noncurrent	[3]	61	66
Gas Storage Inventory Adjustments [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory assets, noncurrent	[3]	$ 18	21
Energy Optimization Plan Incentive [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory Current Asset, End Date for Recovery	[4]	2,016
Noncurrent Regulatory Asset Recovery End Date	[3],[4]	2,017
Regulatory assets, current	[4]	$ 16	17
Regulatory assets, noncurrent	[3],[4]	$ 18	17
Major Maintenance [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory Current Asset, End Date for Recovery	[2]	2,015
Regulatory assets, current	[2]		8
Other Regulatory Assets [Member] | Consumers Energy Company [Member]
Regulatory Matters [Line Items]
Regulatory Current Asset, End Date for Recovery	[2]	2,015
Regulatory assets, current	[2]		3
Regulatory assets, noncurrent		$ 2	$ 1
[1]	This regulatory asset is offset partially by liabilities. The net amount is included in rate base, thereby providing a return.
[2]	These regulatory assets are included in rate base (or are expected to be included, for costs incurred subsequent to the most recently approved rate case), thereby providing a return on expenditures, or provide a specific return on investment authorized by the MPSC.
[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 alternative revenue programs and are not associated with incurred costs or capital investments. Therefore, the MPSC has provided for recovery without a return.

Regulatory Matters (Schedule 56

Regulatory Matters (Schedule of the Components of PSCR and GCR Over/(Under) Recoveries) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accrued gas revenue		$ 27
Accrued rate refunds	$ 26	6
Consumers Energy Company [Member]
Accrued gas revenue		27
Accrued rate refunds	$ 26	$ 6

Contingencies And Commitments57

Contingencies And Commitments (Contingencies And Commitments) (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)sitelawsuit	Dec. 31, 2014USD ($)
Loss Contingencies [Line Items]
Increase due to change in estimate		$ 74
Regulatory assets		1,840	$ 1,956
Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Increase due to change in estimate		74
Regulatory assets		$ 1,840	$ 1,956
Bay Harbor [Member]
Loss Contingencies [Line Items]
Environmental remediation permit renewal term		5 years
Demand for payment by USEPA		$ 8
Accrual for environmental loss contingencies		$ 58
Discounted projected costs rate		4.34%
Remaining undiscounted obligation amount		$ 74
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
Remediation and other response activity costs, minimum		3
Remediation and other response activity costs, maximum		8
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies		$ 114
Discounted projected costs rate		2.57%
Remaining undiscounted obligation amount		$ 129
Number of former MGPs | site		23
Regulatory assets		$ 146
Authorized recovery, collection period		10 years
Accrual for environmental loss contingencies, inflation rate		2.50%
Coal Ash Disposal [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Increase due to change in estimate	$ 68
Electric Utility [Member] | NREPA [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies		$ 3
Remediation and other response activity costs, minimum		3
Remediation and other response activity costs, maximum		5
Gas Utility [Member] | NREPA [Member] | Consumers Energy Company [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies		1
Remediation and other response activity costs, maximum		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
Individual Lawsuits [Member]
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit		1

Contingencies And Commitments58

Contingencies And Commitments (Expected Remediation Cost By Year) (Details) $ in Millions	Dec. 31, 2015USD ($)
Manufactured Gas Plant [Member] | Consumers Energy Company [Member]
Site Contingency [Line Items]
Undiscounted amount due in next fiscal year	$ 14
Undiscounted amount due within two year	19
Undiscounted amount due within third year	11
Undiscounted amount due within fourth year	14
Undiscounted amount due within five year	19
Bay Harbor [Member]
Site Contingency [Line Items]
Undiscounted amount due in next fiscal year	6
Undiscounted amount due within two year	5
Undiscounted amount due within third year	5
Undiscounted amount due within fourth year	5
Undiscounted amount due within five year	$ 4

Contingencies And Commitments59

Contingencies And Commitments (Guarantees) (Details) $ in Millions		1 Months Ended	12 Months Ended
		Dec. 31, 2015USD ($)$ / MWhMW	Dec. 31, 2015USD ($)$ / MWhMW	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Guarantor Obligations [Line Items]
Interest expense reduction			$ (14)	$ (17)	$ (16)
Interest income			$ 12	5	3
Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Expiration Date	[1]		Indefinite
Maximum obligation	[1]	$ 30	$ 30
Interest expense reduction			(2)	(10)	(11)
Interest income			11	4	2
Consumers Energy Company [Member] | Settlement with Taxing Authority [Member]
Guarantor Obligations [Line Items]
Tax examination refund		37	37
Interest expense reduction		12
Interest income		6
PPE reduction resulting from tax refund		19
Reduction of income tax expense		5
Consumers Energy Company [Member] | Refund Of Taxes Paid Receivable [Member] | Settlement with Taxing Authority [Member]
Guarantor Obligations [Line Items]
Tax examination refund		19	19
Consumers Energy Company [Member] | Refund Of Interest Paid Receivable [Member] | Settlement with Taxing Authority [Member]
Guarantor Obligations [Line Items]
Tax examination refund		12	12
Consumers Energy Company [Member] | Interest Receivable [Member] | Settlement with Taxing Authority [Member]
Guarantor Obligations [Line Items]
Tax examination refund		6	$ 6
Guarantees [Member]
Guarantor Obligations [Line Items]
Expiration Date	[1]		Indefinite
Maximum obligation	[1]	51	$ 51
Indemnity Obligations From Asset Sales And Other Agreements [Member]
Guarantor Obligations [Line Items]
Expiration Date	[2]		Indefinite
Maximum obligation	[2]	143	$ 143
Carrying Amount	[2]	7	7
Tax And Other Indemnity Obligations [Member] | Consumers Energy Company [Member] | Maximum [Member]
Guarantor Obligations [Line Items]
Carrying Amount		1	1
MCV PPA [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total		3,003	3,003
Purchase Obligations Due in Year One		335	335
Purchase Obligations Due in Year Two		345	345
Purchase Obligations Due in Year Three		277	277
Purchase Obligations Due in Year Four		321	321
Purchase Obligations Due in Year Five		296	296
Purchase Obligations Due After Year Five		$ 1,429	$ 1,429
Term of Unrecorded Unconditional Purchase Obligations			35 years
Unrecorded Unconditional Purchase Obligations, Minimum Quantity Required | MW		1,240	1,240
Unrecorded Unconditional Purchase Obligation Capacity Charge Per Mwh | $ / MWh		10.14	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			$ 282	300	278
Palisades PPA [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total		$ 2,327	2,327
Purchase Obligations Due in Year One		342	342
Purchase Obligations Due in Year Two		352	352
Purchase Obligations Due in Year Three		363	363
Purchase Obligations Due in Year Four		374	374
Purchase Obligations Due in Year Five		387	387
Purchase Obligations Due After Year Five		509	509
Unrecorded Unconditional Purchase Obligation, Purchases			$ 352	302	338
Unrecorded Unconditional Purchase Obligations, Maximum Quantity | MW			798
Related Parties PPA [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total		977	$ 977
Purchase Obligations Due in Year One		82	82
Purchase Obligations Due in Year Two		82	82
Purchase Obligations Due in Year Three		82	82
Purchase Obligations Due in Year Four		85	85
Purchase Obligations Due in Year Five		87	87
Purchase Obligations Due After Year Five		559	559
Other PPA [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total		3,640	3,640
Purchase Obligations Due in Year One		240	240
Purchase Obligations Due in Year Two		248	248
Purchase Obligations Due in Year Three		247	247
Purchase Obligations Due in Year Four		223	223
Purchase Obligations Due in Year Five		225	225
Purchase Obligations Due After Year Five		2,457	2,457
Unrecorded Unconditional Purchase Obligation, Purchases			347	$ 354	$ 345
PPA [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total		9,947	9,947
Purchase Obligations Due in Year One		999	999
Purchase Obligations Due in Year Two		1,027	1,027
Purchase Obligations Due in Year Three		969	969
Purchase Obligations Due in Year Four		1,003	1,003
Purchase Obligations Due in Year Five		995	995
Purchase Obligations Due After Year Five		4,954	4,954
Other Purchase Obligations [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total		2,200	2,200
Purchase Obligations Due in Year One		904	904
Purchase Obligations Due in Year Two		580	580
Purchase Obligations Due in Year Three		251	251
Purchase Obligations Due in Year Four		111	111
Purchase Obligations Due in Year Five		63	63
Purchase Obligations Due After Year Five		291	291
Other Purchase Obligations [Member] | Consumers Energy Company [Member]
Guarantor Obligations [Line Items]
Purchase Obligations Total		1,908	1,908
Purchase Obligations Due in Year One		870	870
Purchase Obligations Due in Year Two		551	551
Purchase Obligations Due in Year Three		224	224
Purchase Obligations Due in Year Four		83	83
Purchase Obligations Due in Year Five		34	34
Purchase Obligations Due After Year Five		$ 146	$ 146
[1]	At Consumers, this obligation comprises a guarantee provided to the DOE in connection with a settlement agreement regarding damages resulting from the DOE'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 DOE and CMS Energy's 1994 guarantee of non-recourse revenue bonds issued by Genesee. For additional details on this guarantee, see Note 19, 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 Capitalization60

Financings And Capitalization (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Financing And Capitalization [Line Items]
Limitation on payment of stock dividends		$ 3,900
Common stock dividends from Consumers		$ 474
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
Consumers Energy Company [Member]
Financing And Capitalization [Line Items]
Maximum allowed short term securities outstanding under FERC Authorization		$ 800
Maximum allowed long-term securites outstanding under FERC Authorization		1,900
Long-term securities, remaining availability under FERC Authorization		900
Short-term debt, authorized borrowings		800
Short-term borrowings outstanding		249
Unrestricted retained earnings		$ 884
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		0.91%
Short-term debt, authorized borrowings		$ 500
Short-term borrowings outstanding		249
Continuous Equity Program [Member]
Financing And Capitalization [Line Items]
Aggregate sales price of an equity offering program		$ 100
Number of Shares Issued		888,610
Average Price Per Share		$ 33.76
Proceeds		$ 30
Revolving Credit Facilities May 27, 2020 [Member]
Financing And Capitalization [Line Items]
Amount of Facility	[1]	550
Revolving Credit Facilities May 27, 2020 [Member] | Consumers Energy Company [Member]
Financing And Capitalization [Line Items]
Amount of Facility	[2]	$ 650
[1]	Obligations under this facility are secured by Consumers common stock
[2]	Obligations under this facility are secured by FMBs of Consumers.In November 2015, Consumers entered into a new $250 million credit facility and terminated its $250 million accounts receivable sales program.

Financings and Capitalization61

Financings and Capitalization (Summary of Long-Term Debt Outstanding) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Principal amounts outstanding		$ 9,137,000,000	$ 8,547,000,000
Current portion of long-term debt		(684,000,000)	(519,000,000)
Net unamortized discounts		(12,000,000)	(12,000,000)
Total long-term debt		8,441,000,000	8,016,000,000
Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal amounts outstanding		5,409,000,000	5,283,000,000
Current portion of long-term debt		(198,000,000)	(124,000,000)
Net unamortized discounts		(5,000,000)	(5,000,000)
Total long-term debt		5,206,000,000	5,154,000,000
CMS Energy [Member]
Debt Instrument [Line Items]
Principal amounts outstanding		2,630,000,000	2,380,000,000
Net unamortized discounts		(7,000,000)	(7,000,000)
Total long-term debt		$ 2,630,000,000	2,380,000,000
Senior Notes 3.600% Due March 2025 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		3.60%
Term Loan Facility Due 2017 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Maturity Date		2,017
Principal amounts outstanding		$ 180,000,000	180,000,000
Three-month LIBOR plus a spread		0.85%
Interest rate at period end		1.19%
FMB's 2.600% Due 2015 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate		2.60%
FMB's 4.100% Due 2045 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate		4.10%
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] | CMS Energy [Member]
Debt Instrument [Line Items]
Principal amounts outstanding		$ 2,450,000,000	2,200,000,000
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	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	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 3.600% Due March 2025 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Interest rate		3.60%
Maturity Date		2,025
Principal amounts outstanding		$ 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		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]
Debt Instrument [Line Items]
Principal amounts outstanding		$ 1,098,000,000	884,000,000
Other CMS Subsidiaries [Member] | EnerBank Certificates Of Deposit [Member]
Debt Instrument [Line Items]
Interest rate		1.365%
Maturity Date		2016-2025
Interest-bearing Domestic Deposit, Brokered		$ 1,098,000,000	$ 884,000,000
Weighted-average interest rate		1.36%	1.22%
Certificate of deposit face value		$ 1,000
First Mortgage Bonds [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal amounts outstanding		$ 4,773,000,000	$ 4,573,000,000
Weighted-average Interest Rate (%)		4.73%	4.75%
First Mortgage Bonds [Member] | FMB's 2.600% Due 2015 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[1]	2.60%
Maturity Date	[1]	2,015
Principal amounts outstanding	[1]		$ 50,000,000
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	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
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]
Debt Instrument [Line Items]
Principal amounts outstanding		$ 353,000,000	$ 427,000,000
Securitization Bonds [Member] | Consumers Energy Company [Member] | Consumers 2014 Securitization Funding [Member]
Debt Instrument [Line Items]
Weighted-average Interest Rate (%)		2.69%	2.60%
Securitization Bonds [Member] | Securitization Bonds 5.760% Due 2015 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate	[2]	5.76%
Maturity Date		2,015
Principal amounts outstanding			$ 49,000,000
Securitization Bonds [Member] | Securitization Bonds 2.689% Due 2020-2029 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Interest rate		2.689%
Maturity Date	[3]	2020-2029
Principal amounts outstanding		$ 353,000,000	$ 378,000,000
[1]	The weighted-average interest rate for Consumers' FMBs was 4.73 percent at December 31, 2015 and 4.75 percent at December 31, 2014.
[2]	The weighted-average interest rate for Consumers' Securitization bonds issued through its subsidiary Consumers 2014 Securitization Funding was 2.69 percent at December 31, 2015 and 2.60 percent at December 31, 2014.Principal and interest payments are made semiannually.
[3]	Principal and interest payments are made semiannually.

Financings And Capitalization62

Financings And Capitalization (Major Long-Term Debt Transactions) (Details)	12 Months Ended
	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Principal Balance	$ 500,000,000
Debt retirement, principal	50,000,000
CMS Energy [Member]
Debt Instrument [Line Items]
Principal Balance	250,000,000
Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance	250,000,000
Debt retirement, principal	50,000,000
Senior Notes 3.600% Due March 2025 [Member] | CMS Energy [Member]
Debt Instrument [Line Items]
Principal Balance	$ 250,000,000
Interest rate	3.60%
Debt issuance date	November 2015
Maturity date	November 2,025
FMB's 4.100% Due 2045 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Principal Balance	$ 250,000,000
Interest rate	4.10%
Debt issuance date	November 2015
Maturity date	November 2,045
FMB's 2.600% Due 2015 [Member] | Consumers Energy Company [Member]
Debt Instrument [Line Items]
Debt retirement, principal	$ 50,000,000
Interest rate	2.60%
Debt retirement date	October 2015
Maturity date	October 2,015

Financings and Capitalization63

Financings and Capitalization (Debt Maturities) (Details) $ in Millions	Dec. 31, 2015USD ($)
Long-term debt maturities, 2016	$ 684
Long-term debt maturities, 2017	1,010
Long-term debt maturities, 2018	911
Long-term debt maturities, 2019	1,288
Long-term debt maturities, 2020	801
Consumers Energy Company [Member]
Long-term debt maturities, 2016	198
Long-term debt maturities, 2017	375
Long-term debt maturities, 2018	523
Long-term debt maturities, 2019	876
Long-term debt maturities, 2020	$ 426

Financings And Capitalization64

Financings And Capitalization (Revolving Credit Facilities) (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Nov. 30, 2015	Dec. 31, 2015
Revolving Credit Facilities May 27, 2020 [Member]
Line of Credit Facility [Line Items]
Expiration Date	[1]		May 27, 2020
Amount of Facility	[1]		$ 550
Amount Borrowed	[1]
Letters of Credit Outstanding	[1]		$ 1
Amount Available	[1]		$ 549
Revolving Credit Facilities May 27, 2020 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	[2]		May 27, 2020
Amount of Facility	[2]		$ 650
Amount Borrowed	[2]
Letters of Credit Outstanding	[2]		$ 9
Amount Available	[2]		$ 641
Revolving Credit Facilities November 23, 2017 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	[2],[3]		Nov. 23, 2017
Amount of Facility		$ 250	$ 250	[2],[3]
Amount Borrowed	[2],[3]
Amount Available	[2],[3]		$ 250
Revolving Credit Facilities May 9, 2018 [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Expiration Date	[2]		May 9, 2018
Amount of Facility	[2]		$ 30
Amount Borrowed	[2]
Letters of Credit Outstanding	[2]		$ 30
Short Term Secured Borrowing Accounts Receivable Sales Program [Member] | Consumers Energy Company [Member]
Line of Credit Facility [Line Items]
Short term borrowings, program terminated		$ 250
[1]	Obligations under this facility are secured by Consumers common stock
[2]	Obligations under this facility are secured by FMBs of Consumers.In November 2015, Consumers entered into a new $250 million credit facility and terminated its $250 million accounts receivable sales program.
[3]	In November 2015, Consumers entered into a new $250 million credit facility and terminated its $250 million accounts receivable sales program.

Financings and Capitalization65

Financings and Capitalization (Preferred Stock of Subsidiary) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2015	Dec. 31, 2014
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, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	$ 158	$ 110
Restricted cash equivalents	[1]	19	38
Nonqualified deferred compensation plan assets	[1]	10	8
Commodity contracts	[1]	1	2
Total	[1]	336	289
Nonqualified deferred compensation plan liabilities	[1],[2]	10	8
Commodity contracts	[1]		1
Total	[1]	10	9
Consumers Energy Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]		19
Restricted cash equivalents	[1]	19	38
Nonqualified deferred compensation plan assets	[1]	7	6
Commodity contracts	[1]	1	2
Total	[1]	162	196
Nonqualified deferred compensation plan liabilities	[1],[2]	7	6
Commodity contracts	[1]		1
Total	[1]	7	7
DB SERP [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	2	4
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	3
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]	146	127
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]	104	90
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]	$ 29	$ 38
[1]	All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3 and which were insignificant at December 31, 2015 and 2014.
[2]	All assets and liabilities were classified as Level 1 with the exception of some commodity contracts, which were classified as Level 3 and which were insignificant at December 31, 2015 and 2014.

Fair Value Measurements (Asse67

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance at beginning of period		$ 1	$ 4	$ 2
Total gains (losses) included in earnings		(1)
Total gains (losses) offset through regulatory accounting		2	(15)	3
Purchases		1	(1)
Settlements		(2)	13	(1)
Balance at end of period		1	1	4
Unrealized gains (losses) included in earnings relating to assets and liabilities still held at end of period	[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	4	2
Total gains (losses) offset through regulatory accounting		2	(15)	3
Purchases			(1)
Settlements		(2)	13	(1)
Balance at end of period		$ 1	$ 1	$ 4
[1]	CMS Energy records realized and unrealized gains and losses for Level 3 recurring fair value measurements in earnings as a component of operating revenue or purchased and interchange power on its consolidated statements of income.

Financial Instruments (Narrativ

Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2014
Financial Instruments [Line Items]
Portion of long-term debt supported by third-party credit enhancements	$ 103		$ 103
Consumers Energy Company [Member]
Financial Instruments [Line Items]
Portion of long-term debt supported by third-party credit enhancements	103		$ 103
Gain on CMS Energy common stock	$ 9	$ 4

Financial Instruments (Schedule

Financial Instruments (Schedule Of Carrying Amounts And Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity - Fair Value		$ 11	$ 11
Current notes payable		249	60
Current notes receivable		128	98
Current portion of long-term debt		684	519
DIG Note Payable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current notes payable		1
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity - Fair Value		11	11
Notes payable, Fair Value	[1],[2]	14
Long-term debt, Fair Value	[3]	9,125	8,535
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity - Fair Value		11	11
Notes payable, Fair Value	[1],[2]	14
Long-term debt, Fair Value	[3]	9,599	9,285
Consumers Energy Company [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current notes payable		249	60
Current portion of long-term debt		198	124
Consumers Energy Company [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	[4]	5,404	5,278
Consumers Energy Company [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	[4]	5,684	5,749
EnerBank [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current notes receivable		144	138
EnerBank [Member] | Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, Fair Value	[2],[3]	1,161	938
EnerBank [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, Fair Value	[2],[3]	1,228	995
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		11	11
Long-term debt, Fair Value	[3]	8,648	8,252
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	[4]	4,733	4,716
Fair Value, Inputs, Level 3 [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable, Fair Value	[1],[2]	14
Long-term debt, Fair Value	[3]	951	1,033
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 debt, Fair Value	[4]	951	1,033
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	[2],[3]	$ 1,228	$ 995
[1]	Includes current portion of notes payable of $1 million at December 31, 2015.
[2]	Includes current portion of notes receivable of $144 million at December 31, 2015 and $138 million at December 31, 2014.
[3]	Includes current portion of long-term debt of $684 million at December 31, 2015 and $519 million at December 31, 2014.
[4]	Includes current portion of long-term debt of $198 million at December 31, 2015 and $124 million at December 31, 2014.

Financial Instruments (Schedu70

Financial Instruments (Schedule Of Investment Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Investment Securities [Line Items]
Held to maturity securities - Cost	$ 11	$ 11
Held to maturity securities - Fair Value	11	11
CMS Energy Common Stock [Member] | Consumers Energy Company [Member]
Investment Securities [Line Items]
Held to maturity securities - Cost	4	5
Held to maturity securities - Unrealized Gains	25	33
Held to maturity securities - Fair Value	29	38
DB SERP [Member] | Mutual Fund [Member]
Investment Securities [Line Items]
Available for sale - Cost	152	129
Available for sale - Unrealized Losses	6	2
Available for sale - Fair Value	146	127
DB SERP [Member] | Mutual Fund [Member] | Consumers Energy Company [Member]
Investment Securities [Line Items]
Available for sale - Cost	108	92
Available for sale - Unrealized Losses	4	2
Available for sale - Fair Value	$ 104	$ 90

Financial Instruments (Summary

Financial Instruments (Summary of the Sales Activity for Investment Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Proceeds from Sales of Available-for-Sale Securities	$ 3	$ 8	$ 3
Consumers Energy Company [Member]
Proceeds from Sales of Available-for-Sale Securities	$ 2	$ 6	$ 2

Notes Receivable (Narrative) (D

Notes Receivable (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sale of notes receivable	$ 48
Current notes receivable	128	$ 98
EnerBank notes receivable held for sale	16	41
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sale of notes receivable	48
Current notes receivable	144	138
Delinquent loans	8	5
Loans modified as troubled debt restructurings	1	1
Receivables Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 16	$ 41

Notes Receivable (Schedule Of C

Notes Receivable (Schedule Of Current And Non-Current Notes Receivable) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 128	$ 98
EnerBank notes receivable held for sale	16	41
Total notes receivable	1,161	939
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	144	138
Noncurrent notes receivable	1,017	800
Receivables, Net Of Allowance For Loan Losses [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	128	97
Receivables Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 16	41
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable		$ 1

Notes Receivable (Schedule Of A

Notes Receivable (Schedule Of Allowance For Loan Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Notes Receivable [Abstract]
Allowance for loan losses, at beginning of period	$ 8	$ 5
Charge-offs	(8)	(6)
Recoveries	1	1
Provision for loan losses	8	8
Allowance for loan losses, at end of period	$ 9	$ 8

Plant, Property, and Equipmen75

Plant, Property, and Equipment (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)MW	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Property, Plant and Equipment [Line Items]
Payments to acquire plant	$ 1,564	$ 1,577	$ 1,325
Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Payments to acquire plant	$ 1,537	$ 1,573	$ 1,320
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
Goodwill	0
Minimum [Member]
Property, Plant and Equipment [Line Items]
Expected future amortization expense of intangible assets, per year	84
Minimum [Member] | Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Expected future amortization expense of intangible assets, per year	84
Maximum [Member]
Property, Plant and Equipment [Line Items]
Expected future amortization expense of intangible assets, per year	110
Maximum [Member] | Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Expected future amortization expense of intangible assets, per year	$ 110

Plant, Property, and Equipmen76

Plant, Property, and Equipment (Plant, Property, and Equipment Table) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Public Utility, Property, Plant and Equipment [Line Items]
Construction work in progress		$ 1,509	$ 1,106
Less accumulated depreciation and amortization		(5,747)	(5,415)
Total plant, property, and equipment	[1]	14,705	13,412
Public Utilities, Property Plant and Equipment Additions		1,400	1,600
Public Utilities, Property Plant and Equipment Disposals		187	126
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Construction work in progress		1,467	1,103
Less accumulated depreciation and amortization		(5,676)	(5,346)
Total plant, property, and equipment	[1]	14,588	13,337
Public Utilities, Property Plant and Equipment Additions		1,400	1,600
Public Utilities, Property Plant and Equipment Disposals		187	126
Electricity Generation Plant, Non-Nuclear [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing		$ 4,925	4,544
Electricity Generation Plant, Non-Nuclear [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] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Generation		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		$ 4,925	4,544
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]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution		$ 6,809	6,487
Electric Distribution [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		20 years
Electric Distribution [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		75 years
Electric Distribution [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution		$ 6,809	6,487
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 Other [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 1,039	910
Electric Other [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		5 years
Electric Other [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		50 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		$ 1,039	910
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]
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation		$ 286	289
Electric Capital Leases [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation		286	289
Gas Distribution [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution		$ 3,497	3,239
Gas Distribution [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		28 years
Gas Distribution [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Distribution		80 years
Gas Distribution [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution		$ 3,497	3,239
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]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Transmission		$ 981	974
Gas Transmission [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		17 years
Gas Transmission [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Transmission		75 years
Gas Transmission [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Transmission		$ 981	974
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]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	[2]	$ 601	578
Gas Underground Storage Facilities [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] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other	[2]	65 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]	$ 601	578
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]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 630	538
Gas Other [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		5 years
Gas Other [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		50 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		$ 630	538
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]
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation		$ 14	6
Gas Capital Leases [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Capital leases and financing obligation		14	6
Natural Gas [Member] | Gas Underground Storage Facilities [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		26	26
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		$ 95	90
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		$ 25	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		$ 41	41
Other [Member] | Minimum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		2 years
Other [Member] | Maximum [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Estimated Depreciable Life in Years, Other		51 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, 2015, utility plant additions were $1.4 billion and utility plant retirements were $187 million. For the year ended December 31, 2014, utility plant additions were $1.6 billion and utility plant retirements were $126 million.
[2]	Underground storage includes base natural gas of $26 million at December 31, 2015 and 2014. Base natural gas is not subject to depreciation.

Plant, Property, and Equipmen77

Plant, Property, and Equipment (Public Utilities, Allowance for Funds Used During Construction, Schedule of Composite Rate Table) (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consumers Energy Company [Member]
AFUDC capitalization rate	7.10%	7.20%	7.30%

Plant, Property, and Equipmen78

Plant, Property, and Equipment (Schedule of Capital Leased Asssets) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Capital Leased Assets, Gross, Additions	[1]	$ 1,741	$ 1,616	$ 1,408
Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Capital Leased Assets, Gross, Additions	[1]	1,694	1,612	1,403
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation		152	143
Consumers Energy Company [Member] | Assets Held under Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Balance at beginning of period		295	291
Capital Leased Assets, Gross, Additions		17	7
Capital Leased Assets, Gross, Net retirements and other adjustments		(12)	(3)
Balance at end of period		$ 300	$ 295	$ 291
[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 Equipmen79

Plant, Property, and Equipment (Public Utilities Property Plant and Equipment Schedule of Accumulated Depreciation and Amortization) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated Depreciation, Depletion and Amortization	$ 5,747	$ 5,415
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	5,676	5,346
Utility Plant Assets [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated Depreciation, Depletion and Amortization	5,674	5,345
Utility Plant Assets [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	5,674	5,345
Non-Utility Plant Assets [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated Depreciation, Depletion and Amortization	73	70
Non-Utility Plant Assets [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ 2	$ 1

Plant, Property, and Equipmen80

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, 2015	Dec. 31, 2014	Dec. 31, 2013
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	3.50%	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	2.80%	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	8.70%	7.70%	7.00%

Plant, Property, and Equipmen81

Plant, Property, and Equipment (Schedule Of Depreciation And Amortization Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Depreciation expense - plant, property, and equipment	$ 591	$ 551	$ 516
Total depreciation and amortization expense	750	685	628
Securitized Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	83	75	63
Other Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	2	5	6
Software [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	70	50	40
Other Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	4	4	3
Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense - plant, property, and equipment	586	546	511
Total depreciation and amortization expense	744	678	622
Consumers Energy Company [Member] | Securitized Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	83	75	63
Consumers Energy Company [Member] | Other Regulatory Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	2	5	6
Consumers Energy Company [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	69	49	39
Consumers Energy Company [Member] | Other Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	$ 4	$ 3	$ 3

Plant, Property, and Equipmen82

Plant, Property, and Equipment (Schedule of Finite-Lived Intangible Assets by Major Class Table) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	$ 930	$ 787
Finite-Lived Intangible Assets, Accumulated Amortization		368	293
Public Utilities, Property Plant and Equipment Additions		1,400	1,600
Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	925	785
Finite-Lived Intangible Assets, Accumulated Amortization		365	291
Public Utilities, Property Plant and Equipment Additions		1,400	1,600
Software and Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	734	596
Finite-Lived Intangible Assets, Accumulated Amortization		294	223
Software and Software Development Costs [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	729	594
Finite-Lived Intangible Assets, Accumulated Amortization		291	221
Leasehold Improvements [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1],[2]	7	5
Finite-Lived Intangible Assets, Accumulated Amortization	[2]	5	4
Leasehold Improvements [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1],[2]	7	5
Finite-Lived Intangible Assets, Accumulated Amortization	[2]	5	4
Intangible Plant [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Public Utilities, Property Plant and Equipment Additions		140	96
Rights of Way [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	153	150
Finite-Lived Intangible Assets, Accumulated Amortization		46	44
Rights of Way [Member] | Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	153	150
Finite-Lived Intangible Assets, Accumulated Amortization		46	44
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]	21	21
Finite-Lived Intangible Assets, Accumulated Amortization		15	14
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	$ 14
Minimum [Member] | Software and Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		2 years
Minimum [Member] | Software and 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 and Software Development Costs [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Finite-Lived Intangible Asset, Useful Life		15 years
Maximum [Member] | Software and 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]	Net intangible asset additions for Consumers' utility plant were $140 million during 2015 and $96 million during 2014 and primarily represented software development costs.
[2]	Leasehold improvements are amortized over the life of the lease, which may change whenever the lease is renewed or extended.

Plant, Property, and Equipmen83

Plant, Property, and Equipment (Jointly Owned Regulated Utility Facilities) (Details) $ in Millions	Dec. 31, 2015USD ($)
J.H. Campbell Unit 3 [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Ownership share	93.30%
Utility plant in service	$ 1,078
Accumulated depreciation	(542)
Construction work-in-progress	494
Net investment	$ 1,030
Ludington [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Ownership share	51.00%
Utility plant in service	$ 245
Accumulated depreciation	(151)
Construction work-in-progress	157
Net investment	251
Distribution [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Utility plant in service	200
Accumulated depreciation	(63)
Construction work-in-progress	4
Net investment	$ 141

Leases (Narrative) (Details)

Leases (Narrative) (Details) - Consumers Energy Company [Member]	12 Months Ended
	Dec. 31, 2015
Leases [Line Items]
Finance Lease Term	15 years
Coal-Carrying Railcars [Member]
Leases [Line Items]
Operating leases without extension provisions, remaining term	10 years
Operating leases with extension provisions, remaining term	11 years
Gas Transportation Pipeline into Karn [Member]
Leases [Line Items]
Capital Lease Term	15 years
Capital Lease Remaining Term	6 years
Gas Transportation Pipeline into Zeeland [Member]
Leases [Line Items]
Capital Lease Term	5 years
Capital lease renewal term	5 years
Capital Lease Remaining Term	2 years
Minimum [Member] | Coal-Carrying Railcars [Member]
Leases [Line Items]
Operating leases, term	1 year
Minimum [Member] | Long-term PPAs [Member]
Leases [Line Items]
Lease term	1 year
Maximum [Member] | Coal-Carrying Railcars [Member]
Leases [Line Items]
Operating leases, term	15 years
Maximum [Member] | Vehicle Fleet Operations [Member]
Leases [Line Items]
Capital Lease Term	120 months
Maximum [Member] | Long-term PPAs [Member]
Leases [Line Items]
Lease term	17 years

Leases (Schedule of Rent Expens

Leases (Schedule of Rent Expense) (Details) - Consumers Energy Company [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Leases [Line Items]
Contingent rental expense	[1]	$ 82	$ 85	$ 77
PPAs [Member]
Leases [Line Items]
Minimum operating lease expense		6	6	6
Non-PPAs [Member]
Leases [Line Items]
Minimum operating lease expense		$ 19	$ 19	$ 21
[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 (Schedule of Future Mini

Leases (Schedule of Future Minimum Lease Payments for Leases) (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Leases [Line Items]
Capital and Financing Leases, Non-current portion		$ 118	$ 123
Consumers Energy Company [Member]
Leases [Line Items]
Capital and Financing Leases, Non-current portion		118	123
Operating Leases, 2016		20
Operating Leases, 2017		19
Operating Leases, 2018		16
Operating Leases, 2019		10
Operating Leases, 2020		10
Operating Leases, 2021 and thereafter		29
Operating Leases, Total minimum lease payments		104
Finance Leases Lessee Balance Sheet Assets Amortization And Interest Charges		18	$ 19	$ 20
Consumers Energy Company [Member] | Capital Leases [Member]
Leases [Line Items]
Capital and Financing Leases, 2016		14
Capital and Financing Leases, 2017		14
Capital and Financing Leases, 2018		13
Capital and Financing Leases, 2019		13
Capital and Financing Leases, 2020		11
Capital and Financing Leases, 2021 and thereafter		36
Capital and Financing Leases, Total minimum lease payments		101
Capital and Financing Leases, Less imputed interest		43
Capital and Financing Leases, Present value of net minimum lease payments		58
Capital and Financing Leases, Less current portion		9
Capital and Financing Leases, Non-current portion		49
Consumers Energy Company [Member] | Financing Leases [Member]
Leases [Line Items]
Capital and Financing Leases, 2016	[1]	17
Capital and Financing Leases, 2017	[1]	17
Capital and Financing Leases, 2018	[1]	16
Capital and Financing Leases, 2019	[1]	15
Capital and Financing Leases, 2020	[1]	14
Capital and Financing Leases, 2021 and thereafter	[1]	17
Capital and Financing Leases, Total minimum lease payments	[1]	96
Capital and Financing Leases, Less imputed interest	[1]	14
Capital and Financing Leases, Present value of net minimum lease payments	[1]	82
Capital and Financing Leases, Less current portion	[1]	13
Capital and Financing Leases, Non-current portion	[1]	$ 69
[1]	In 2007, Consumers sold Palisades to Entergy and entered into a 15-year PPA to buy all of the capacity and energy then capable of being produced by Palisades. Consumers has continuing involvement with Palisades through security provided to Entergy for Consumers' PPA obligation and other arrangements. Because of these ongoing arrangements, Consumers accounted for the transaction as a financing of Palisades and not a sale. Accordingly, no gain on the sale of Palisades was recognized on the consolidated statements of income. Consumers accounted for the remaining non-real-estate assets and liabilities associated with the transaction as a sale.Palisades remains on Consumers' consolidated balance sheets and Consumers continues to depreciate it. Consumers recorded the related proceeds as a financing obligation with payments recorded to interest expense and the financing obligation based on the amortization of the obligation over the life of the Palisades PPA. The value of the financing obligation was determined based on an allocation of the transaction proceeds to the fair values of the net assets sold and fair value of the plant asset under the financing. Total amortization and interest charges under the financing were $18 million for the year ended December 31, 2015, $19 million for the year ended December 31, 2014, and $20 million for the year ended December 31, 2013.

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	$ 340	$ 325
Incurred	11	9
Settled	(6)	(12)
Accretion	20	$ 18
Cash flow Revisions	74
ARO Liability, end of period	439	$ 340
Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	339	324
Incurred	11	9
Settled	(6)	(12)
Accretion	20	$ 18
Cash flow Revisions	74
ARO Liability, end of period	438	$ 339
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	120	118
Settled		(3)
Accretion	6	$ 5
Cash flow Revisions	74
ARO Liability, end of period	200	$ 120
Gas Distribution Cut, Purge, Cap [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	162	154
Incurred	11	6
Settled	(6)	(8)
Accretion	11	$ 10
Cash flow Revisions
ARO Liability, end of period	178	$ 162
Asbestos Abatement [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	51	49
Settled		(1)
Accretion	3	$ 3
Cash flow Revisions
ARO Liability, end of period	54	$ 51
Wind Parks [Member] | Consumers Energy Company [Member]
Asset Retirement Obligations [Line Items]
ARO Liability, at beginning of period	$ 6	3
Incurred		$ 3
Settled
Accretion
Cash flow Revisions
ARO Liability, end of period	$ 6	$ 6

Retirement Benefits (Narrative)

Retirement Benefits (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)item	Dec. 31, 2014USD ($)item	Dec. 31, 2013USD ($)item
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 262	$ 32	$ 229
Union employees percentage	40.00%
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 243	29	222
Union employees percentage	42.00%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	$ 2,013	$ 1,979	$ 1,964
Estimated time of amortization of gains losses	10 years	10 years	10 years
Postretirement benefits contributions	$ 225
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
Postretirement benefits contributions	$ 209
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	$ 1,208	$ 1,265	$ 1,218
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	13 years	13 years	13 years
Estimated time of prior service cost	10 years		10 years
Postretirement benefits contributions	$ 29	$ 25
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	$ 1,133	$ 1,186	$ 1,141
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	13 years	13 years	13 years
Estimated time of prior service cost	10 years		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]
Employer contribution, percentage of base pay	6.00%	6.00%	6.00%
Plan cost, defined contribution plan	$ 16	$ 13	$ 10
Defined Company Contribution Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contribution, percentage of base pay	6.00%	6.00%	6.00%
Plan cost, defined contribution plan	$ 16	$ 13	$ 10
DC SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum years of participation before vesting	5 years
Trust assets	$ 2	2
DC SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum years of participation before vesting	5 years
Trust assets	$ 2	2
401 (K) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan cost, defined contribution plan	$ 19	$ 18	$ 17
Employer match of eligible contributions	60.00%	60.00%	60.00%
Employer match of eligible wages	6.00%	6.00%	6.00%
401 (K) Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan cost, defined contribution plan	$ 19	$ 18	$ 17
Employer match of eligible contributions	60.00%	60.00%	60.00%
Employer match of eligible wages	6.00%	6.00%	6.00%
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] | 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	7.25%	6.50%
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	7.25%	6.50%
Over Age 65 [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year	8.00%	6.50%
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	8.00%	6.50%

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, 2014
Defined Benefit Plan Disclosure [Line Items]
ABO	$ 140	$ 145
Contributions	25
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
ABO	97	99
Contributions	17
DB SERP Trust Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	148	131
DB SERP Trust Assets [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Trust assets	$ 106	$ 93

Retirement Benefits (Schedule90

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, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components	$ 11
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	168
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components	(9)
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	(137)
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	11
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	164
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components	(9)
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	$ (133)

Retirement Benefits (Schedule91

Retirement Benefits (Schedule Of Assumptions Used) (Details)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual rate of return on plan assets		(2.00%)	7.40%	12.50%
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]	4.52%	4.10%	4.90%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	[2]	3.00%	3.00%	3.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	[1],[2],[3]	4.10%	4.90%	4.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	[2],[4]	7.50%	7.50%	7.75%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	[2]	3.00%	3.00%	3.00%
Actual rate of return on plan assets		(2.00%)	7.40%	12.50%
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]	4.43%	4.10%	4.90%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	[2]	5.50%	5.50%	5.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	[1],[2],[3]	4.10%	4.90%	4.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	[2]	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]	4.70%	4.30%	5.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	[1],[2],[3]	4.30%	5.10%	4.40%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	[2],[4]	7.25%	7.25%	7.25%
[1]	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.
[2]	The mortality assumption for 2015 and 2014 for benefit obligations was based on the RP-2014 mortality table, with projection scales MP-2015 for 2015 and MP-2014 for 2014. The mortality assumption for 2013 was based on the RP-2000 mortality tables with projection of future mortality improvements using Scale AA, which aligned with the IRS prescriptions for cash funding valuations under the Pension Protection Act of 2006. The mortality assumption for net periodic benefit cost for 2015 was based on the RP-2014 mortality table with projection scale MP-2014, and for 2014 and 2013 was based on the RP-2000 mortality table.
[3]	In January 2016, CMS Energy and Consumers changed the method in which they determine the discount rate used to calculate the service cost and interest expense 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 expense; 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. CMS Energy and Consumers expect that this change will result in a decrease in the service cost and interest expense components of net periodic benefit costs for the DB Pension and OPEB Plans, with an offsetting impact to the actuarial gain or loss recorded in, and later amortized from, the associated regulatory asset and AOCI. This change represents a change in accounting estimate and will not impact years prior to 2016.
[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 7.5 percent in 2015. The actual return (loss) on DB Pension Plan assets was (2.0) percent in 2015, 7.4 percent in 2014, and 12.5 percent in 2013.

Retirement Benefits (Schedule92

Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension And DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 50	$ 42	$ 54
Interest expense	108	105	100
Expected return on plan assets	(138)	(135)	(127)
Amortization of Net loss	97	60	101
Amortization of Prior service cost (credit)	1	1	3
Net periodic cost (credit)	118	73	131
Pension And DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	49	41	52
Interest expense	103	100	96
Expected return on plan assets	(134)	(131)	(124)
Amortization of Net loss	93	59	98
Amortization of Prior service cost (credit)	1	1	3
Net periodic cost (credit)	112	70	125
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	25	20	29
Interest expense	58	56	65
Expected return on plan assets	(91)	(88)	(77)
Amortization of Net loss	21	2	26
Amortization of Prior service cost (credit)	(41)	(41)	(31)
Net periodic cost (credit)	(28)	(51)	12
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	25	20	28
Interest expense	56	54	63
Expected return on plan assets	(86)	(83)	(72)
Amortization of Net loss	22	3	27
Amortization of Prior service cost (credit)	(40)	(40)	(30)
Net periodic cost (credit)	$ (23)	$ (46)	$ 16

Retirement Benefits (Schedule93

Retirement Benefits (Schedule Of Net Loss And Prior Service Cost (Credit) That Will Be Amortized In 2015) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset	$ 72
AOCI	1
Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset	72
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset	(18)
AOCI	(2)
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset	$ (18)

Retirement Benefits (Schedule94

Retirement Benefits (Schedule Of Benefit Obligations In Excess Of Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		$ 2,547	$ 2,073
Service cost		49	41
Interest cost		102	99
Plan amendments		13
Actuarial (gain) loss		(153)	458
Benefits paid		(155)	(124)
Benefit obligation at end of period		2,403	2,547	$ 2,073
Plan assets at fair value at beginning of period		1,979	1,964
Actual return on plan assets		(36)	139
Company contributions		225
Actual benefits paid		(155)	(124)
Plan assets at fair value at end of period		2,013	1,979	1,964
Funded status	[1],[2]	(390)	(568)
Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status		(368)	(532)
DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		156	132
Service cost		1	1
Interest cost		6	6
Actuarial (gain) loss		(5)	24
Benefits paid		(8)	(7)
Benefit obligation at end of period		150	156	132
Company contributions		8	7
Actual benefits paid		(8)	(7)
Funded status		(150)	(156)
DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		111	93
Service cost		1	1
Interest cost		4	4
Actuarial (gain) loss		(5)	17
Benefits paid		(5)	(4)
Benefit obligation at end of period		106	111	93
Company contributions		5	4
Actual benefits paid		(5)	(4)
Funded status		(106)	(111)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		1,378	1,123
Service cost		25	20	29
Interest cost		58	56	65
Plan amendments		(25)
Actuarial (gain) loss		(152)	230
Benefits paid	[3]	(57)	(51)
Benefit obligation at end of period		1,227	1,378	1,123
Plan assets at fair value at beginning of period		1,265	1,218
Actual return on plan assets		(29)	72
Company contributions		29	25
Actual benefits paid	[3]	(57)	(50)
Plan assets at fair value at end of period		1,208	1,265	1,218
Funded status		(19)	(113)
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received			4	5
OPEB [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received		1
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of period		1,336	1,088
Service cost		25	20	28
Interest cost		56	54	63
Plan amendments		(24)
Actuarial (gain) loss		(150)	223
Benefits paid	[3]	(55)	(49)
Benefit obligation at end of period		1,188	1,336	1,088
Plan assets at fair value at beginning of period		1,186	1,141
Actual return on plan assets		(27)	68
Company contributions		29	25
Actual benefits paid	[3]	(55)	(48)
Plan assets at fair value at end of period		1,133	1,186	1,141
Funded status		(55)	(150)
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received			$ 4	$ 4
OPEB [Member] | Consumers Energy Company [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received		$ 1
[1]	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. At December 31, 2014, $532 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses.
[2]	The actuarial loss for 2014 was primarily the result of lowering the discount rates used in calculating the plans' obligations and using the RP-2014 mortality table during the annual measurement of benefit obligations.
[3]	CMS Energy received less than $1 million in 2015, $4 million in 2014, and $5 million in 2013 for the Medicare Part D subsidies. Consumers received less than $1 million in 2015 and $4 million in each of 2014 and 2013 for the Medicare Part D subsidies. The Medicare Part D subsidy payments are used to pay OPEB Plan benefits.

Retirement Benefits (Schedule95

Retirement Benefits (Schedule Of Retirement Benefit Plan Assets (Liabilities)) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Non-current (liabilities)	$ (591)	$ (872)
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current (liabilities)	(529)	(793)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current (liabilities)	(390)	(568)
Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current (liabilities)	(368)	(532)
DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Current assets (liabilities)	(8)	(8)
Non-current (liabilities)	(142)	(148)
DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Current assets (liabilities)	(5)	(5)
Non-current (liabilities)	(101)	(106)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current (liabilities)	(19)	(113)
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current (liabilities)	$ (55)	$ (150)

Retirement Benefits (Schedule96

Retirement Benefits (Schedule Of Accumulated And Projected Benefit Obligations) (Details) - Pension Plan [Member] - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Pension PBO	$ 2,403	$ 2,547	$ 2,073
Pension ABO	2,140	2,257
Fair value of Pension Plan assets	$ 2,013	$ 1,979	$ 1,964

Retirement Benefits (Schedule97

Retirement Benefits (Schedule Of Net Periodic Benefit Cost Not yet Recognized) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Pension And DB SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets (liabilities), Net loss	$ 944	$ 1,012
Regulatory assets (liabilities), Prior service cost (credit)	19	7
Regulatory assets (liabilities)	963	1,019
AOCI, Net loss (gain)	86	99
AOCI, Prior service cost (credit)	1	1
Total amounts not yet recognized as component of net periodic benefit cost	1,050	1,119
Pension And DB SERP [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets (liabilities), Net loss	944	1,012
Regulatory assets (liabilities), Prior service cost (credit)	19	7
Regulatory assets (liabilities)	963	1,019
AOCI, Net loss (gain)	29	39
Total amounts not yet recognized as component of net periodic benefit cost	992	1,058
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets (liabilities), Net loss	360	419
Regulatory assets (liabilities), Prior service cost (credit)	(227)	(243)
Regulatory assets (liabilities)	133	176
AOCI, Net loss (gain)	(11)	(18)
AOCI, Prior service cost (credit)	(8)	(8)
Total amounts not yet recognized as component of net periodic benefit cost	114	150
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets (liabilities), Net loss	360	419
Regulatory assets (liabilities), Prior service cost (credit)	(227)	(243)
Regulatory assets (liabilities)	133	176
Total amounts not yet recognized as component of net periodic benefit cost	$ 133	$ 176

Retirement Benefits (Schedule98

Retirement Benefits (Schedule Of Allocation Of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	$ 2,013	$ 1,979
Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	753	629
Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1,260	1,350
Pension Plan [Member] | Cash and Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	215	31
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	215	31
Pension Plan [Member] | U.S. Government and Agencies Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	19	30
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	19	30
Pension Plan [Member] | Corporate Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	243	222
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	243	222
Pension Plan [Member] | State and Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	8	8
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	8	8
Pension Plan [Member] | Foreign Corporate Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	16	21
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	16	21
Pension Plan [Member] | Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	538	598
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	538	598
Pension Plan [Member] | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	974	1,069
Pension Plan [Member] | Pooled Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	974	1,069
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1,208	1,265
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	1,133	1,186
OPEB [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	561	526
OPEB [Member] | Fair Value, Inputs, Level 1 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	526	494
OPEB [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	647	739
OPEB [Member] | Fair Value, Inputs, Level 2 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	607	692
OPEB [Member] | Cash and Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	51	19
OPEB [Member] | Cash and Short-Term Investments [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	48	18
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	51	19
OPEB [Member] | Cash and Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	48	18
OPEB [Member] | U.S. Government and Agencies Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	3	5
OPEB [Member] | U.S. Government and Agencies Securities [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	3	4
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	5
OPEB [Member] | U.S. Government and Agencies Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	3	4
OPEB [Member] | Corporate Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	34	33
OPEB [Member] | Corporate Debt [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	32	31
OPEB [Member] | Corporate Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	34	33
OPEB [Member] | Corporate Debt [Member] | Fair Value, Inputs, Level 2 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	32	31
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] | Consumers Energy Company [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] | State and Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Consumers Energy Company [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	2	3
OPEB [Member] | Foreign Corporate Debt [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	2	3
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	2	3
OPEB [Member] | Foreign Corporate Debt [Member] | Fair Value, Inputs, Level 2 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	2	3
OPEB [Member] | Common Stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	54	69
OPEB [Member] | Common Stocks [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	51	65
OPEB [Member] | Common Stocks [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	54	69
OPEB [Member] | Common Stocks [Member] | Fair Value, Inputs, Level 1 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	51	65
OPEB [Member] | Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	456	438
OPEB [Member] | Mutual Funds [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	427	411
OPEB [Member] | Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	456	438
OPEB [Member] | Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	427	411
OPEB [Member] | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	607	697
OPEB [Member] | Pooled Funds [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	569	653
OPEB [Member] | Pooled Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	607	697
OPEB [Member] | Pooled Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	$ 569	$ 653

Retirement Benefits (Schedule99

Retirement Benefits (Schedule Of Pooled Funds Components) (Details)	Dec. 31, 2015	Dec. 31, 2014
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
U.S. equity securities	62.00%	64.00%
Foreign equity securities	18.00%	16.00%
U.S. fixed-income securities	11.00%	9.00%
Foreign fixed-income securities	6.00%	6.00%
Alternative investments	3.00%	5.00%
Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
U.S. equity securities	62.00%	64.00%
Foreign equity securities	18.00%	16.00%
U.S. fixed-income securities	11.00%	9.00%
Foreign fixed-income securities	6.00%	6.00%
Alternative investments	3.00%	5.00%
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
U.S. equity securities	58.00%	62.00%
Foreign equity securities	13.00%	12.00%
U.S. fixed-income securities	22.00%	18.00%
Foreign fixed-income securities	5.00%	5.00%
Alternative investments	2.00%	3.00%
OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
U.S. equity securities	58.00%	62.00%
Foreign equity securities	13.00%	12.00%
U.S. fixed-income securities	22.00%	18.00%
Foreign fixed-income securities	5.00%	5.00%
Alternative investments	2.00%	3.00%

Retirement Benefits (Schedul100

Retirement Benefits (Schedule Of Plan Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 262	$ 32	$ 229
Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	243	29	$ 222
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
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	225
Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	209
VEBA Trust [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	29	16
VEBA Trust [Member] | OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 29	16
401 (h) Component [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions		9
401 (h) Component [Member] | OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions		$ 9
Equity Securities [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	50.00%
Equity Securities [Member] | OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	50.00%
Equity Securities [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	50.00%
Equity Securities [Member] | Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	50.00%
Fixed Income Funds [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	30.00%
Fixed Income Funds [Member] | OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	30.00%
Fixed Income Funds [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	30.00%
Fixed Income Funds [Member] | Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	30.00%
Alternative Strategy Investments [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	20.00%
Alternative Strategy Investments [Member] | OPEB [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	20.00%
Alternative Strategy Investments [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	20.00%
Alternative Strategy Investments [Member] | Pension Plan [Member] | Consumers Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	20.00%

Retirement Benefits (Schedul101

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

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)shares
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	5,611,442
Tax benefits recognized in equity | $	$ 1
Unrealized Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation | $	$ 33
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	5,611,442
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
Market-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	3 years
Time-Lapsed Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Time-Lapsed Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period	1 year
Shares vested	0
Shares forfeited	0

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule Of Restricted Stock Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	802,782
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	763,099
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	789,602
Weighted-Average Grant Date Fair Value per Share, Granted	$ 36.84	$ 26.15	$ 16.65
Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	750,262
Weighted-Average Grant Date Fair Value per Share, Granted	$ 36.83	$ 26.18	$ 16.76
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	13,180
Number of Shares, Vested	0
Number of Shares, Forfeited	0
Weighted-Average Grant Date Fair Value per Share, Granted	$ 34.25
Restricted Stock Units (RSUs) [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	12,837
Weighted-Average Grant Date Fair Value per Share, Granted	$ 34.25
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	1,679,595
Number of Shares, Vested	(793,103)
Number of Shares, Forfeited	(64,340)
Number of Shares, at end of period	1,624,934	1,679,595
Weighted-Average Grant Date Fair Value per Share, at beginning of period	$ 24.69
Weighted-Average Grant Date Fair Value per Share, Vested	27.76
Weighted-Average Grant Date Fair Value per Share, Forfeited	26.93
Weighted-Average Grant Date Fair Value per Share, at end of period	$ 29.08	$ 24.69
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	1,614,684
Number of Shares, Vested	(756,286)
Number of Shares, Forfeited	(63,840)
Number of Shares, at end of period	1,557,657	1,614,684
Weighted-Average Grant Date Fair Value per Share, at beginning of period	$ 24.71
Weighted-Average Grant Date Fair Value per Share, Vested	27.74
Weighted-Average Grant Date Fair Value per Share, Forfeited	26.93
Weighted-Average Grant Date Fair Value per Share, at end of period	$ 29.06	$ 24.71

Stock-Based Compensation (Sc104

Stock-Based Compensation (Schedule Of Restricted Stock Granted) (Details)	12 Months Ended
	Dec. 31, 2015shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	802,782
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	763,099
Time-Lapsed Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	152,820
Time-Lapsed Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	146,536
Market-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	158,385
Market-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	149,909
Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	158,385
Performance-Based Restricted Stock [Member] | Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	149,909
Time-Lapsed Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	12,848
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	12,514
Dividends On Market-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	22,208
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	21,129
Dividends On Performance-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	11,046
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	10,502
Dividends On Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	332
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	323
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	286,758
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	272,277

Stock-Based Compensation (Sc105

Stock-Based Compensation (Schedule Of Share-Based Payment Award, Restricted Stock, Valuation Assumptions) (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock-Based Compensation [Abstract]
Expected volatility	14.10%	15.60%	17.40%
Expected dividend yield	3.30%	3.70%	3.90%
Risk-free rate	0.80%	0.80%	0.40%

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value per Share, Granted	$ 36.84	$ 26.15	$ 16.65
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	36.83	$ 26.18	$ 16.76
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	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	$ 34.25

Stock-Based Compensation (Sc107

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	$ 29	$ 16	$ 10
Allocated Share-based Compensation Expense	20	14	14
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	8	5	5
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 15
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 9 months 18 days
Consumers Energy Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	$ 28	15	9
Allocated Share-based Compensation Expense	19	13	14
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	7	$ 5	$ 5
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 15
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 9 months 18 days

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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
Interest and penalties	0	$ 0	$ 0
IRS audit, adjustments to income tax expense	0
Electric Utility [Member] | Consumers Energy Company [Member]
Income Tax Benefits [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]
Income Tax Benefits [Line Items]
Income tax benefits, to be returned to customers	$ 260
Tax benefit, distribution to customers, term	12 years

Income Taxes (Schedule Of Effec

Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Income from continuing operataions before income taxes	$ 796	$ 729	$ 756
Income tax expense at statutory rate	279	255	265
State and local income taxes, net of federal effect	39	36	37
Accelerated flow-through of regulatory tax benefits	(39)	(39)
Other, net	(8)	(2)
Income Tax Expense	$ 271	$ 250	$ 302
Effective income tax rate	34.00%	34.30%	39.90%
Consumers Energy Company [Member]
Income Taxes [Line Items]
Income from continuing operataions before income taxes	$ 896	$ 873	$ 880
Income tax expense at statutory rate	314	306	308
State and local income taxes, net of federal effect	42	42	43
Accelerated flow-through of regulatory tax benefits	(39)	(39)
Other, net	(15)	(3)	(5)
Income Tax Expense	$ 302	$ 306	$ 346
Effective income tax rate	33.70%	35.10%	39.30%

Income Taxes (Significant Compo

Income Taxes (Significant Components Of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
State and Local	$ 24	$ 24	$ 34
Total Current Income Tax Expense	24	24	34
Federal, deferred income taxes	192	198	248
State and Local, deferred income taxes	36	31	23
Total Deferred Income Tax Expense	228	229	271
Deferred income tax credit	19	(3)	(3)
Tax Expense	271	250	302
Consumers Energy Company [Member]
Federal	66	8	137
State and Local	32	36	45
Total Current Income Tax Expense	98	44	182
Federal, deferred income taxes	153	236	147
State and Local, deferred income taxes	32	29	20
Total Deferred Income Tax Expense	185	265	167
Deferred income tax credit	19	(3)	(3)
Tax Expense	$ 302	$ 306	$ 346

Income Taxes (Principal Compone

Income Taxes (Principal Components Of Deferred Income Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Employee benefits	$ (127)	$ (72)
Gas inventory	(96)	(117)
Property, plant and equipment	(2,429)	(2,217)
Net regulatory tax liability	50	65
Reserves and accruals	59	63
Securitized costs	(122)	(144)
Tax loss and credit carryforwards	657	676
Other	(5)
Gross Deferred Tax Liabilities	(2,013)	(1,746)
Less: valuation allowance	(4)	(2)
Total net deferred income tax liabilities	(2,017)	(1,748)
Deferred tax assets, net of valuation reserves	762	802
Deferred tax liabilities	(2,779)	(2,550)
Consumers Energy Company [Member]
Employee benefits	(156)	(103)
Gas inventory	(96)	(117)
Property, plant and equipment	(2,457)	(2,263)
Net regulatory tax liability	50	65
Reserves and accruals	30	34
Securitized costs	(122)	(144)
Tax loss and credit carryforwards	46	45
Other	(5)	(2)
Gross Deferred Tax Liabilities	(2,710)	(2,485)
Less: valuation allowance		(1)
Total net deferred income tax liabilities	(2,710)	(2,486)
Deferred tax assets, net of valuation reserves	126	143
Deferred tax liabilities	$ (2,836)	$ (2,629)

Income Taxes (Loss And Credit C

Income Taxes (Loss And Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2015USD ($)
Operating Loss Carryforwards [Line Items]
Total tax attributes	$ 657
Consumers Energy Company [Member]
Operating Loss Carryforwards [Line Items]
Total tax attributes	46
Federal Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, Gross Amount	885
Federal net operating loss carryforward, Tax Attribute	311
Federal Tax Authority [Member] | Consumers Energy Company [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, Gross Amount	121
Federal net operating loss carryforward, Tax Attribute	42
Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, Gross Amount	414
Local net operating loss carryforwards, Tax Attribute	4
Valuation Allowance - Loss carryforward	1
Alternative Minimum Tax [Member]
Operating Loss Carryforwards [Line Items]
Tax credits, Gross Amount	270
Alternative minimum tax credits, Tax Attribute	270
Charitable Contribution Carryover [Member]
Operating Loss Carryforwards [Line Items]
Charitable contribution carryforwards	2
Charitable contribution carryover, Tax Attribute	1
Charitable Contribution Carryover [Member] | Consumers Energy Company [Member]
Operating Loss Carryforwards [Line Items]
Charitable contribution carryforwards	2
Charitable contribution carryover, Tax Attribute	1
General Business Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax credits, Gross Amount	71
General business credits, Tax Attribute	71
Valuation Allowance - Loss carryforward	3
General Business Tax Credit Carryforward [Member] | Consumers Energy Company [Member]
Operating Loss Carryforwards [Line Items]
Tax credits, Gross Amount	3
General business credits, Tax Attribute	$ 3

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Beginning And Ending Uncertain Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Balance at beginning of period	$ 5	$ 4	$ 1
Additions for current year tax positions	1	2
Additions for prior year tax positions	1	1	3
Reductions for prior year tax positions	(1)	(2)
Balance at end of period	6	5	4
Consumers Energy Company [Member]
Balance at beginning of period	5	4	1
Additions for current year tax positions	1	2
Additions for prior year tax positions	1	1	3
Reductions for prior year tax positions	(1)	(2)
Balance at end of period	$ 6	$ 5	$ 4

Earnings Per Share - CMS Ene114

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, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share - CMS Energy [Abstract]
Net Income	$ 107		$ 148		$ 68		$ 202		$ 97		$ 94		$ 84		$ 204		$ 525	$ 479	$ 454
Less income attributable to noncontrolling interest	1				1				1				1				2	2	2
Net Income Available to Common Stockholders	$ 106		$ 148		$ 67		$ 202		$ 96		$ 94		$ 83		$ 204		$ 523	$ 477	$ 452
Weighted average shares - basic																	275.6	270.6	264.5
Add dilutive contingently convertible securities																		3.1	6.4
Add dilutive non-vested stock awards																	0.9	0.9	1
Weighted average shares - diluted																	276.5	274.6	271.9
Basic	$ 0.39	[1]	$ 0.53	[1]	$ 0.25	[1]	$ 0.73	[1]	$ 0.35	[1]	$ 0.34	[1]	$ 0.31	[1]	$ 0.77	[1]	$ 1.90	$ 1.76	$ 1.71
Diluted	$ 0.38	[1]	$ 0.53	[1]	$ 0.25	[1]	$ 0.73	[1]	$ 0.35	[1]	$ 0.34	[1]	$ 0.30	[1]	$ 0.75	[1]	1.89	1.74	1.66
Dividends declared per common share																	$ 1.16	$ 1.08	$ 1.02
[1]	The sum of the quarters may not equal annual EPS due to changes in the number of shares outstanding.

Other Income and Other Expen115

Other Income and Other Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fee income	$ 9	$ 8	$ 7
All other	1	3	3
Total other income	10	11	10
Civic and political expenditures	(10)	(14)	(5)
Donations	(1)	(15)	(4)
Loss on reacquired and extinguished debt		(20)	(4)
All other	(6)	(6)	(7)
Total other expense	(17)	(55)	(20)
Consumers Energy Company [Member]
Fee income	9	8	7
Gain on CMS Energy common stock	9		4
All other	1	2	3
Total other income	19	10	14
Civic and political expenditures	(10)	(14)	(5)
Donations	(1)	(15)	(4)
All other	(6)	(6)	(7)
Total other expense	$ (17)	$ (35)	$ (16)

Reportable Segments (Details)

Reportable Segments (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating Revenue		$ 1,509	$ 1,486	$ 1,350	$ 2,111	$ 1,758	$ 1,430	$ 1,468	$ 2,523	$ 6,456	$ 7,179	$ 6,566
Depreciation and amortization										750	685	628
Income (loss) from equity method investees	[1]									14	15	13
Interest charges										396	407	398
Income tax expense (benefit)										271	250	302
Net Income Attributable to CMS Energy		106	148	67	202	96	94	83	204	523	477	452
Plant, property, and equipment, gross		18,943				17,721				18,943	17,721	16,184
Investments in equity method investees	[1]	64				61				64	61	59
Total Assets		20,340				19,185				20,340	19,185	17,290
Capital expenditures	[2]									1,741	1,616	1,408
Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue		1,439	1,417	1,281	2,028	1,672	1,359	1,387	2,382	6,165	6,800	6,321
Depreciation and amortization										744	678	622
Interest charges										250	250	245
Income tax expense (benefit)										302	306	346
Net Income Available to Common Stockholders		134	$ 160	$ 83	$ 215	117	$ 119	$ 108	$ 221	592	565	532
Plant, property, and equipment, gross		18,797				17,580				18,797	17,580	16,044
Total Assets		18,658				17,847				18,658	17,847	16,179
Capital expenditures	[2]									1,694	1,612	1,403
Electric Utility [Member]
Segment Reporting Information [Line Items]
Operating Revenue										4,249	4,436	4,173
Depreciation and amortization										567	522	484
Interest charges										178	181	179
Income tax expense (benefit)										224	211	242
Net Income Attributable to CMS Energy										437	384	363
Plant, property, and equipment, gross		13,059				12,230				13,059	12,230	11,186
Total Assets	[3]	12,676				11,582				12,676	11,582	10,487
Capital expenditures	[2]									1,136	1,139	996
Electric Utility [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue										4,249	4,436	4,173
Depreciation and amortization										567	522	484
Interest charges										178	181	179
Income tax expense (benefit)										224	211	242
Net Income Available to Common Stockholders										437	384	363
Plant, property, and equipment, gross		13,059				12,230				13,059	12,230	11,186
Total Assets	[3]	12,676				11,582				12,676	11,582	10,487
Capital expenditures	[2]									1,136	1,139	996
Gas Utility [Member]
Segment Reporting Information [Line Items]
Operating Revenue										1,916	2,363	2,148
Depreciation and amortization										177	156	138
Interest charges										71	67	64
Income tax expense (benefit)										78	95	104
Net Income Attributable to CMS Energy										154	179	168
Plant, property, and equipment, gross		5,723				5,335				5,723	5,335	4,843
Total Assets	[3]	5,918				5,391				5,918	5,391	4,784
Capital expenditures	[2]									558	473	407
Gas Utility [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue										1,916	2,363	2,148
Depreciation and amortization										177	156	138
Interest charges										71	67	64
Income tax expense (benefit)										78	95	104
Net Income Available to Common Stockholders										154	179	168
Plant, property, and equipment, gross		5,723				5,335				5,723	5,335	4,843
Total Assets	[3]	5,918				5,391				5,918	5,391	4,784
Capital expenditures	[2]									558	473	407
Enterprises [Member]
Segment Reporting Information [Line Items]
Operating Revenue										190	299	181
Depreciation and amortization										4	4	3
Income (loss) from equity method investees	[1]									14	15	13
Income tax expense (benefit)										3	(1)	(4)
Net Income Attributable to CMS Energy										4	(1)	2
Plant, property, and equipment, gross		120				115				120	115	115
Investments in equity method investees	[1]	61				58				61	58	57
Total Assets		270				231				270	231	231
Capital expenditures	[2]									44	3	1
Other [Member]
Segment Reporting Information [Line Items]
Operating Revenue										101	81	64
Depreciation and amortization										2	3	3
Interest charges										147	159	155
Income tax expense (benefit)										(34)	(55)	(40)
Net Income Attributable to CMS Energy										(72)	(85)	(81)
Plant, property, and equipment, gross		41				41				41	41	40
Investments in equity method investees	[1]	3				3				3	3	2
Total Assets		1,476				1,981				1,476	1,981	1,788
Capital expenditures	[2]									3	1	4
Other [Member] | Consumers Energy Company [Member]
Segment Reporting Information [Line Items]
Operating Revenue											1
Interest charges										1	2	2
Net Income Available to Common Stockholders										1	2	1
Plant, property, and equipment, gross		15				15				15	15	15
Total Assets		$ 64				$ 874				$ 64	$ 874	$ 908
[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 -117

Related Party Transactions - Consumers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Purchased power - related parties	$ 83	$ 90	$ 90
Accounts payable - related parties, current	9	10
Accounts receivable - related parties	11	11
Consumers Energy Company [Member]
Related Party Transaction [Line Items]
Purchased power - related parties	83	89	$ 89
Accounts payable - related parties, current	15	12
Accounts receivable - related parties	17	1
Due to related parties	23	12
Investments	29	$ 38
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, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	$ 59	$ 57
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 Partnerships) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
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

Quarterly Financial And Comm120

Quarterly Financial And Common Stock Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended																12 Months Ended
		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Operating Revenue		$ 1,509		$ 1,486		$ 1,350		$ 2,111		$ 1,758		$ 1,430		$ 1,468		$ 2,523		$ 6,456	$ 7,179	$ 6,566
Operating Income (Loss)		245		317		204		397		273		236		235		408		1,163	1,152	1,142
Net Income		107		148		68		202		97		94		84		204		525	479	454
Income Attributable to Noncontrolling Interests		1				1				1				1				2	2	2
Net income (loss) attributable to CMS Energy		$ 106		$ 148		$ 67		$ 202		$ 96		$ 94		$ 83		$ 204		$ 523	$ 477	$ 452
Basic Earnings Per Average Common Share		$ 0.39	[1]	$ 0.53	[1]	$ 0.25	[1]	$ 0.73	[1]	$ 0.35	[1]	$ 0.34	[1]	$ 0.31	[1]	$ 0.77	[1]	$ 1.90	$ 1.76	$ 1.71
Diluted Earnings Per Average Common Share		$ 0.38	[1]	$ 0.53	[1]	$ 0.25	[1]	$ 0.73	[1]	$ 0.35	[1]	$ 0.34	[1]	$ 0.30	[1]	$ 0.75	[1]	$ 1.89	$ 1.74	$ 1.66
CMS Energy [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Operating Income (Loss)																		$ (9)	$ (6)	$ (6)
Net Income																		523	477	452
Net income (loss) attributable to CMS Energy																		523	477	452
Consumers Energy Company [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Operating Revenue		$ 1,439		$ 1,417		$ 1,281		$ 2,028		$ 1,672		$ 1,359		$ 1,387		$ 2,382		6,165	6,800	6,321
Operating Income (Loss)		246		305		192		379		264		245		227		399		1,122	1,135	1,118
Net Income		135		160		84		215		118		119		109		221		594	567	534
Preferred stock dividends		1				1				1				1				2	2	2
Net Income Available to Common Stockholders		$ 134		$ 160		$ 83		$ 215		$ 117		$ 119		$ 108		$ 221		$ 592	$ 565	$ 532
Maximum [Member] | CMS Energy Common Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Share price	[2]	$ 37.17		$ 35.82		$ 35.57		$ 38.20		$ 36.42		$ 30.87		$ 31.15		$ 29.28		$ 37.17	$ 36.42
Minimum [Member] | CMS Energy Common Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Share price	[2]	$ 34.24		$ 32.10		$ 31.39		$ 32.83		$ 29.78		$ 28.18		$ 28.87		$ 26.12		$ 34.24	$ 29.78
[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 Finan121

Schedule I - Condensed Financial Information of Registrant (Condensed Statements of Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other operating expense									$ (1,238)	$ (1,232)	$ (1,236)
General taxes									262	252	234
Total operating expenses									(5,293)	(6,027)	(5,424)
Operating Loss	$ 245	$ 317	$ 204	$ 397	$ 273	$ 236	$ 235	$ 408	1,163	1,152	1,142
Interest income									12	5	3
Total other income (expense)									29	(16)	12
Interest on long-term debt									386	393	385
Intercompany interest expense and other									14	17	16
Total interest charges									396	407	398
Income Before Income Taxes									796	729	756
Income Tax Expense									271	250	302
Net income (loss) attributable to CMS Energy	$ 106	$ 148	$ 67	$ 202	$ 96	$ 94	$ 83	$ 204	523	477	452
CMS Energy [Member]
Other operating expense									(9)	(6)	(6)
Total operating expenses									(9)	(6)	(6)
Operating Loss									(9)	(6)	(6)
Equity earnings of subsidiaries									625	585	566
Interest income									1	1	1
Other expense									(9)	(20)	(8)
Total other income (expense)									617	566	559
Interest on long-term debt									134	150	148
Intercompany interest expense and other									3	2	3
Total interest charges									137	152	151
Income Before Income Taxes									471	408	402
Income Tax Expense									(52)	(69)	(50)
Net income (loss) attributable to CMS Energy									$ 523	$ 477	$ 452

Schedule I - Condensed Finan122

Schedule I - Condensed Financial Information of Registrant (Condensed Statements Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Income	$ 107	$ 148	$ 68	$ 202	$ 97	$ 94	$ 84	$ 204	$ 525	$ 479	$ 454
Deferred income taxes									228	229	271
Accounts and notes receivable									120	(31)	(120)
Accounts payable									(26)	50	4
Other current and non-current assets and liabilities									(19)	(15)	(88)
Net cash provided by operating activities									1,640	1,447	1,421
Net cash used in investing activities									(2,044)	(1,910)	(1,532)
Proceeds from issuance of debt									599	1,428	1,025
Issuance of common stock									43	43	36
Retirement of long-term debt									(224)	(750)	(741)
Increase (decrease) in notes payable									189	(110)	60
Net cash provided by financing activities									463	498	190
Net Increase (Decrease) in Cash and Cash Equivalents									59	35	79
Cash and Cash Equivalents, Beginning of Period				$ 207				$ 172	207	172	93
Cash and Cash Equivalents, End of Period	$ 266				$ 207				266	207	172
CMS Energy [Member]
Net Income									523	477	452
Equity earnings of subsidiaries									(625)	(585)	(566)
Dividends received from subsidiaries									499	544	435
Deferred income taxes									(24)	30	48
Accounts and notes receivable									(86)	(3)	(3)
Accounts payable									16	(2)	2
Accrued taxes									(115)	97	48
Other current and non-current assets and liabilities									21	31	18
Net cash provided by operating activities									209	589	434
Investment in subsidiaries									(150)	(495)	(150)
Return of capital										178
Net cash used in investing activities									(150)	(317)	(150)
Proceeds from issuance of debt									349	550	275
Issuance of common stock									43	43	36
Retirement of long-term debt									(100)	(547)	(275)
Payment of dividends on common stock									(320)	(293)	(271)
Debt issuance costs and financing fees									(3)	(6)	(4)
Increase (decrease) in notes payable									(28)	(19)	(47)
Net cash provided by financing activities									$ (59)	$ (272)	(286)
Net Increase (Decrease) in Cash and Cash Equivalents											(2)
Cash and Cash Equivalents, Beginning of Period											$ 2
Cash and Cash Equivalents, End of Period

Schedule I - Condensed Finan123

Schedule I - Condensed Financial Information of Registrant (Condensed Balance Sheets) (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Notes and accrued interest receivable		$ 128	$ 98
Accounts receivable, including intercompany and related parties		11	11
Total current assets		2,320	2,597
Less accumulated depreciation and amortization		5,747	5,415
Total plant, property, and equipment	[1]	14,705	13,412
Other		384	352
Total other non-current assets		3,315	3,176
Total Assets		20,340	19,185	$ 17,290
Current portion of long-term debt		706	540
Accounts and notes payable, including intercompany and related parties		9	10
Accrued interest, including intercompany		106	108
Accrued taxes		349	316
Other liabilities current		142	163
Total current liabilities		2,302	1,948
Long-term debt		8,441	8,016
Net unamortized discounts		(12)	(12)
Postretirement benefits		591	872
Other non-current liabilities		313	299
Total non-current liabilities		14,063	13,530
Common stockholders' equity		3,938	3,670
Total Liabilities and Equity		20,340	19,185
CMS Energy [Member]
Notes and accrued interest receivable		88	2
Accounts receivable, including intercompany and related parties		9	9
Total current assets		97	11
Plant, property, and equipment, gross		16	16
Less accumulated depreciation and amortization		$ 16	$ 16
Total plant, property, and equipment
Deferred income taxes		$ 340	$ 317
Invetment in subsidiaries		6,240	5,961
Other investments - DB SERP		26	22
Other		23	23
Total other non-current assets		6,629	6,323
Total Assets		6,726	6,334
Accounts and notes payable, including intercompany and related parties		74	86
Accrued interest, including intercompany		38	37
Accrued taxes		23	138
Other liabilities current		5	4
Total current liabilities		140	265
Long-term debt		2,630	2,380
Net unamortized discounts		(7)	(7)
Postretirement benefits		22	24
Other non-current liabilities		3	2
Total non-current liabilities		2,648	2,399
Common stockholders' equity		3,938	3,670
Total Liabilities and Equity		$ 6,726	$ 6,334
[1]	For the year ended December 31, 2015, utility plant additions were $1.4 billion and utility plant retirements were $187 million. For the year ended December 31, 2014, utility plant additions were $1.6 billion and utility plant retirements were $126 million.

Schedule I - Condensed Finan124

Schedule I - Condensed Financial Information of Registrant (Narrative) (Details) $ in Millions	Dec. 31, 2015USD ($)
CMS Energy [Member]
Maximum potential obligation	$ 328

Schedule II - Valuation and 125

Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Uncollectible Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	[1]	$ 40	$ 33	$ 32
Charged to Expense	[1]	$ 50	$ 72	$ 63
Charged to other Accounts	[1]
Deductions	[1]	$ 62	$ 65	$ 62
Balance at End of Period	[1]	28	40	33
Allowance for Uncollectible Accounts [Member] | Consumers Energy Company [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		39	31	30
Charged to Expense		$ 50	$ 72	$ 63
Charged to other Accounts
Deductions		$ 61	$ 64	$ 62
Balance at End of Period		28	39	31
Deferred Tax Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		2	$ 2	$ 3
Charged to Expense		3
Charged to other Accounts		(1)
Deductions				$ 1
Balance at End of Period		4	$ 2	2
Deferred Tax Valuation Allowance [Member] | Consumers Energy Company [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 1	$ 1	$ 1
Charged to Expense
Charged to other Accounts		$ (1)
Deductions
Balance at End of Period			$ 1	$ 1
Allowance For Notes Receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	[1]	$ 8	5	5
Charged to Expense	[1]	$ 8	$ 8	$ 4
Charged to other Accounts	[1]
Deductions	[1]	$ 7	$ 5	$ 4
Balance at End of Period	[1]	$ 9	$ 8	$ 5
[1]	Deductions are write-offs of uncollectible accounts, net of recoveries.