Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Income from continuing operataions before income taxes	$ 756	$ 622	$ 606
Income from continuing operations before income taxes	754	620	604
Income tax expense at statutory rate	264	217	211
MCIT law change, net of federal effect			(32)	[1]
State and local income taxes, net of federal effect	37	27	21
Other, net	1	1	(9)
Income Tax Expense	302	245	191
Effective income tax rate	40.10%	39.50%	31.60%
Deferred Income Tax Expense (Benefit)	271	226	169
Consumers Energy Company [Member]
Income Taxes [Line Items]
Income from continuing operataions before income taxes	880	736	734
Income tax expense at statutory rate	308	258	257
State and local income taxes, net of federal effect	43	36	24
Other, net	(5)	3	(14)
Income Tax Expense	346	297	267
Effective income tax rate	39.30%	40.40%	36.40%
Recognition of regulatory asset related to law change	1,570	2,322
Deferred Income Tax Expense (Benefit)	167	153	165
State Jurisdiction [Member]
Income Taxes [Line Items]
MCIT rate			6.00%
Tax Law Change [Member]
Income Taxes [Line Items]
Deferred Income Tax Expense (Benefit)			(32)
Tax Law Change [Member] | Consumers Energy Company [Member]
Income Taxes [Line Items]
Recognition of regulatory asset related to law change			$ 128

[1] For the year ended December 31, 2011, CMS Energy and Consumers remeasured their Michigan deferred income tax assets and liabilities due to the enactment in May 2011 of the MCIT, which became effective January 1, 2012. The MCIT, a simplified six percent corporate income tax, replaced the MBT, a complex multi-part tax. CMS Energy recognized a one-time non-cash deferred tax benefit of $32 million as a result of this remeasurement. Consumers recognized a $128 million regulatory asset (not including the effects of income tax gross-ups) related to this change in tax law.