Schedule I - Condensed Financial Information of Registrant (Condensed Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009		Dec. 31, 2008
Notes receivable	$ 49		$ 70
Accounts receivable - related parties	10		10
Deferred income taxes	24		0
Total current assets	2,565		2,759
Less accumulated depreciation and amortization	4,901		4,646
Investsment in subsidiaries	50		49
Other	276		245
Total other non-current assets	3,254		2,788
Total Assets	16,452	[1]	15,616	[1]	15,256	[1]
Current portion of long-term debt	1,057		750
Accounts payable - related parties	9		9
Accrued interest	101		102
Accrued taxes	282		302
Other liabilities current	159		144
Total current liabilities	2,338		2,021
Long-term debt	6,040		6,448
Unamortized Discount	(20)		(32)
Postretirement benefits	1,289		1,135
Other non-current liabilities	336		267
Total non-current liabilities	11,042		10,758
Common stockholders' equity	3,028		2,793
Total equity	3,072		2,837		2,938		2,815
Total Liabilities and Equity	16,452		15,616
CMS Energy Corporation [Member]
Notes receivable	1		1
Accounts receivable - related parties	6		5
Accrued taxes	16
Deferred income taxes	3		13
Total current assets	26		19
Plant, Property, and Equipment, at cost	16		16
Less accumulated depreciation and amortization	(16)		(16)
Deferred income taxes	367		372
Investsment in subsidiaries	5,096		4,941
Other investment - SERP	23		19
Other	28		27
Total other non-current assets	5,514		5,359
Total Assets	5,540		5,378
Current portion of long-term debt	398		437
Accounts payable - related parties	163		156
Accrued interest	28		27
Accrued taxes			81
Other liabilities current	5		5
Total current liabilities	594		706
Long-term debt	1,875		1,848
Related Party	34		34
Unamortized Discount	(17)		(28)
Postretirement benefits	24		23
Other non-current liabilities	2		2
Total non-current liabilities	1,918		1,879
Common stockholders' equity	3,028		2,793
Total Liabilities and Equity	$ 5,540		$ 5,378

[1] Amounts include a portion of Consumers' other common assets attributable to both the electric and gas utility businesses.