Schedule I - Condensed Financial Information of Registrant (Condensed Statements of Income) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Other operating expense									$ 1,237,000,000		$ 1,206,000,000		$ 1,163,000,000
General taxes									205,000,000		210,000,000		217,000,000
Total operating expenses									5,500,000,000		5,454,000,000		5,507,000,000
Operating Income	174,000,000	316,000,000	207,000,000	306,000,000	158,000,000	319,000,000	262,000,000	239,000,000	1,003,000,000		978,000,000		698,000,000
Interest income									9,000,000		19,000,000		18,000,000
Total other income									18,000,000		43,000,000		72,000,000
Interest on long-term debt									396,000,000		394,000,000		383,000,000
Intercompany interest expense and other									23,000,000		40,000,000		56,000,000
Total interest charges									415,000,000		431,000,000		435,000,000
Income Before Income Taxes									606,000,000		590,000,000		335,000,000
Income Tax Expense Benefit									191,000,000		224,000,000		115,000,000
Income from Continuing Operations	41,000,000	140,000,000	101,000,000	133,000,000	31,000,000	146,000,000	100,000,000	89,000,000	415,000,000		366,000,000		220,000,000
Loss From Discontinued Operations				2,000,000	(6,000,000)		(16,000,000)	(1,000,000)	2,000,000	[1]	(23,000,000)	[2]	20,000,000	[3]
Net Income	41,000,000	140,000,000	101,000,000	135,000,000	25,000,000	146,000,000	84,000,000	88,000,000	417,000,000		343,000,000		240,000,000
Charge for Deferred Issuance Costs on Preferred Stock						8,000,000			0		8,000,000		0
Preferred Stock Dividends						3,000,000	2,000,000	3,000,000	0		8,000,000		11,000,000
Net Income Available to Common Stockholders	41,000,000	139,000,000	100,000,000	135,000,000	25,000,000	134,000,000	80,000,000	85,000,000	415,000,000		324,000,000		218,000,000
CMS Energy Corporation [Member]
Other operating expense									(9,000,000)		(6,000,000)		(10,000,000)
General taxes									6,000,000
Total operating expenses									(3,000,000)		(6,000,000)		(10,000,000)
Operating Income									(3,000,000)		(6,000,000)		(10,000,000)
Equity earnings of subsidiaries									510,000,000		464,000,000		310,000,000
Interest income									1,000,000		1,000,000
Other income (expense)									(5,000,000)		(8,000,000)		12,000,000
Total other income									506,000,000		457,000,000		322,000,000
Interest on long-term debt									143,000,000		147,000,000		124,000,000
Interest on preferred securities													8,000,000
Intercompany interest expense and other									6,000,000		4,000,000		8,000,000
Total interest charges									149,000,000		151,000,000		140,000,000
Income Before Income Taxes									354,000,000		300,000,000		172,000,000
Income Tax Expense Benefit									(61,000,000)		(50,000,000)		(57,000,000)
Income from Continuing Operations									415,000,000		350,000,000		229,000,000
Loss From Discontinued Operations											(10,000,000)
Net Income									415,000,000		340,000,000		229,000,000
Charge for Deferred Issuance Costs on Preferred Stock											8,000,000
Preferred Stock Dividends											8,000,000		11,000,000
Net Income Available to Common Stockholders									$ 415,000,000		$ 324,000,000		$ 218,000,000

[1] Includes an operating gain of $3 million related to a litigation settlement at CMS Viron.

[2] Includes an operating loss of $2 million ($1 million net of tax) at Exeter, whose assets and liabilities were reclassified as held for sale in 2009. Also includes disposal-related losses of $10 million in additional tax expense resulting from an IRS audit adjustment related to a 2003 asset sale, a $6 million ($4 million net of tax) loss for the write down of CMS Energy's investment in Exeter, a $5 million ($3 million net of tax) loss for the increase in a liability for a 2007 asset sale, and a $5 million ($3 million net of tax) loss on the settlement of a 2002 asset sale indemnity.

[3] Includes an operating loss of $11 million ($7 million net of tax) at Exeter and a loss of $3 million ($2 million net of tax) related to a litigation settlement at CMS Viron. Also includes a gain for the expiration of an indemnity obligation related to a 2007 asset sale. CMS Energy provided an indemnity to TAQA in connection with the sale of its ownership interests in businesses in the Middle East, Africa, and India, and recorded a $50 million provision for the contingent liability. This indemnity expired in 2009 and CMS Energy eliminated the liability from its consolidated balance sheets, recognizing a $45 million benefit ($28 million net of tax) to income (loss) from discontinued operations and a $5 million benefit to gain on asset sales, net.