Other Income and Other Expense (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Regulatory return on capital expenditures		$ 17	$ 26
Gain on investment			8
Return on stranded and security costs	3	4	5
All other	13	11	13
Total other income	16	32	80
Donations	(11)	(6)
Civic and political expenditures	(3)	(3)	(3)
All other	(7)	(7)	(9)
Total other expense	(22)	(24)	(30)
Consumers Energy Company [Member]
Regulatory return on capital expenditures		17	26
Gain on investment			5
Return on stranded and security costs	3	4	5
All other	12	10	11
Total other income	19	31	47
Donations	(11)	(6)
Civic and political expenditures	(3)	(3)	(3)
All other	(6)	(6)	(8)
Total other expense	(20)	(15)	(11)
Gain on Early Retirement of Long-term Debt [Member]
Gain (Loss) on extinguishment of debt			28
Loss on Reaquired and Extinguished Debt [Member]
Gain (Loss) on extinguishment of debt	(1)	(8)	(18)
Investment in CMS Energy common stock [Member] | Consumers Energy Company [Member]
Gain on investment	4
Supplemental Executive Retirement Plan [Member] | Consumers Energy Company [Member]
Gain on investment			$ 5