Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents	$ 522	$ 207
Restricted cash and cash equivalents	49	37
Accounts receivable and accrued revenue, less allowances	908	881
Notes receivable	103	98
Notes receivable held for sale	49	41
Accounts receivable - related parties	11	11
Accrued gas revenue		27
Inventories at average cost
Gas in underground storage	328	681
Materials and supplies	115	117
Generating plant fuel stock	97	120
Deferred property taxes	178	216
Regulatory assets	57	89
Prepayments and other current assets	84	72
Total current assets	2,501	2,597
Plant, Property, and Equipment
Plant, property, and equipment, gross	17,930	17,721
Less accumulated depreciation and amortization	5,545	5,415
Plant, property, and equipment, net	12,385	12,306
Construction work in progress	1,141	1,106
Total plant, property, and equipment	13,526	13,412
Other Non-current Assets
Regulatory assets	1,932	1,956
Accounts and notes receivable, less allowances	823	807
Investments	62	61
Other	354	352
Total other non-current assets	3,171	3,176
Total Assets	19,198	19,185
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation	543	540
Notes payable		60
Accounts payable	512	678
Accounts payable - related parties	9	10
Accrued rate refunds	23	6
Accrued interest	67	108
Accrued taxes	239	316
Deferred income taxes	21	66
Regulatory liabilities	68	67
Other current liabilities	117	163
Total current liabilities	1,599	2,014
Non-current Liabilities
Long-term debt	8,143	8,016
Non-current portion of capital leases and financing obligation	117	123
Regulatory liabilities	2,139	2,095
Postretirement benefits	844	872
Asset retirement obligations	344	340
Deferred investment tax credit	58	37
Deferred income taxes	1,811	1,682
Other non-current liabilities	304	299
Total non-current liabilities	13,760	13,464
Commitments and Contingencies (Notes 2 and 3)
Equity
Common stock	3	3
Other paid-in capital	4,783	4,774
Accumulated other comprehensive loss	(48)	(49)
Retained earnings (Accumulated deficit)	(936)	(1,058)
Total common stockholders' equity	3,802	3,670
Noncontrolling interests	37	37
Total equity	3,839	3,707
Total Liabilities and Equity	19,198	19,185
Consumers Energy Company [Member]
Current Assets
Cash and cash equivalents	425	71
Restricted cash and cash equivalents	49	37
Accounts receivable and accrued revenue, less allowances	888	863
Accounts receivable - related parties	1	1
Accrued gas revenue		27
Inventories at average cost
Gas in underground storage	328	681
Materials and supplies	110	113
Generating plant fuel stock	94	112
Deferred property taxes	178	216
Regulatory assets	57	89
Prepayments and other current assets	78	63
Total current assets	2,208	2,273
Plant, Property, and Equipment
Plant, property, and equipment, gross	17,788	17,580
Less accumulated depreciation and amortization	5,477	5,346
Plant, property, and equipment, net	12,311	12,234
Construction work in progress	1,138	1,103
Total plant, property, and equipment	13,449	13,337
Other Non-current Assets
Regulatory assets	1,932	1,956
Accounts and notes receivable, less allowances	7	7
Investments	28	38
Other	230	236
Total other non-current assets	2,197	2,237
Total Assets	17,854	17,847
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation	135	145
Notes payable		60
Accounts payable	496	662
Accounts payable - related parties	14	12
Accrued rate refunds	23	6
Accrued interest	47	70
Accrued taxes	140	149
Deferred income taxes	67	80
Regulatory liabilities	68	67
Other current liabilities	90	135
Total current liabilities	1,080	1,386
Non-current Liabilities
Long-term debt	5,154	5,154
Non-current portion of capital leases and financing obligation	117	123
Regulatory liabilities	2,139	2,095
Postretirement benefits	766	793
Asset retirement obligations	343	339
Deferred investment tax credit	58	37
Deferred income taxes	2,440	2,406
Other non-current liabilities	241	237
Total non-current liabilities	11,258	11,184
Commitments and Contingencies (Notes 2 and 3)
Equity
Common stock	841	841
Other paid-in capital	3,724	3,574
Accumulated other comprehensive loss	(11)	(7)
Retained earnings (Accumulated deficit)	925	832
Total common stockholders' equity	5,479	5,240
Preferred stock	37	37
Total equity	5,516	5,277
Total Liabilities and Equity	$ 17,854	$ 17,847