Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 195	$ 182
Restricted cash and cash equivalents	26	17
Accounts receivable and accrued revenue, less allowance	1,002	1,032
Notes receivable, less allowance	201	198
Notes receivable held for sale	2	2
Accounts receivable - related parties	13	12
Inventories at average cost
Gas in underground storage	244	458
Materials and supplies	136	133
Generating plant fuel stock	65	81
Deferred property taxes	207	257
Regulatory assets	15	20
Prepayments and other current assets	101	83
Total current assets	2,207	2,475
Plant, Property, and Equipment
Plant, property, and equipment, gross	22,878	22,506
Less accumulated depreciation and amortization	6,682	6,510
Plant, property, and equipment, net	16,196	15,996
Construction work in progress	708	765
Total plant, property, and equipment	16,904	16,761
Other Non-current Assets
Regulatory assets	1,718	1,764
Accounts and notes receivable	1,183	1,187
Investments	67	64
Other	789	799
Total other non-current assets	3,757	3,814
Total Assets	22,868	23,050
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation	1,286	1,103
Notes payable		170
Accounts payable	534	725
Accounts payable - related parties	6	15
Accrued rate refunds	46	33
Accrued interest	77	103
Accrued taxes	265	360
Regulatory liabilities	134	80
Other current liabilities	134	195
Total current liabilities	2,482	2,784
Non-current Liabilities
Long-term debt	8,996	9,123
Non-current portion of capital leases and financing obligation	86	91
Regulatory liabilities	3,747	3,715
Postretirement benefits	778	766
Asset retirement obligations	427	430
Deferred investment tax credit	86	87
Deferred income taxes	1,326	1,269
Other non-current liabilities	307	307
Total non-current liabilities	15,753	15,788
Commitments and Contingencies (Notes 2 and 3)
Common stockholder's equity
Common stock	3	3
Other paid-in capital	5,037	5,019
Accumulated other comprehensive loss	(61)	(50)
Retained earnings (Accumulated deficit)	(383)	(531)
Total common stockholders' equity	4,596	4,441
Noncontrolling interests	37	37
Total equity	4,633	4,478
Total Liabilities and Equity	22,868	23,050
Consumers Energy Company [Member]
Current Assets
Cash and cash equivalents	115	44
Restricted cash and cash equivalents	26	17
Accounts receivable and accrued revenue, less allowance	858	885
Notes receivable, less allowance	17	17
Accounts receivable - related parties	2	2
Inventories at average cost
Gas in underground storage	244	458
Materials and supplies	131	128
Generating plant fuel stock	62	76
Deferred property taxes	207	257
Regulatory assets	15	20
Prepayments and other current assets	89	71
Total current assets	1,766	1,975
Plant, Property, and Equipment
Plant, property, and equipment, gross	22,692	22,318
Less accumulated depreciation and amortization	6,612	6,441
Plant, property, and equipment, net	16,080	15,877
Construction work in progress	688	753
Total plant, property, and equipment	16,768	16,630
Other Non-current Assets
Regulatory assets	1,718	1,764
Accounts and notes receivable	22	22
Investments	1	21
Other	674	687
Total other non-current assets	2,415	2,494
Total Assets	20,949	21,099
Current Liabilities
Current portion of long-term debt, capital leases, and financing obligation	715	365
Notes payable		170
Accounts payable	514	701
Accounts payable - related parties	10	19
Accrued rate refunds	46	33
Accrued interest	50	67
Accrued taxes	484	542
Regulatory liabilities	134	80
Other current liabilities	103	159
Total current liabilities	2,056	2,136
Non-current Liabilities
Long-term debt	5,211	5,561
Non-current portion of capital leases and financing obligation	86	91
Regulatory liabilities	3,747	3,715
Postretirement benefits	721	711
Asset retirement obligations	426	429
Deferred investment tax credit	86	87
Deferred income taxes	1,659	1,640
Other non-current liabilities	244	241
Total non-current liabilities	12,180	12,475
Commitments and Contingencies (Notes 2 and 3)
Common stockholder's equity
Common stock	841	841
Other paid-in capital	4,549	4,449
Accumulated other comprehensive loss	(29)	(12)
Retained earnings (Accumulated deficit)	1,315	1,173
Total common stockholders' equity	6,676	6,451
Preferred stock	37	37
Total equity	6,713	6,488
Total Liabilities and Equity	$ 20,949	$ 21,099