Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Income	$ 454	$ 384	$ 417
Retirement Benefits Liability
Net gain (loss) arising during the period, net of tax	26	(10)	(11)
Prior service credit adjustment, net of tax	5
Amortization of net actuarial loss, net of tax	4	2	2
Investments
Unrealized gain (loss) on investments, net of tax	(2)	2
Other Comprehensive Income (Loss)	33	(6)	(9)
Comprehensive Income	487	378	408
Comprehensive Income Attributable to Noncontrolling Interest	2	2	2
Comprehensive Income Attributable to CMS Energy	485	376	406
Consumers Energy Company [Member]
Net Income	534	439	467
Retirement Benefits Liability
Net gain (loss) arising during the period, net of tax	5	(8)	(4)
Amortization of net actuarial loss, net of tax	3	2	1
Investments
Unrealized gain (loss) on investments, net of tax	1	3	1
Reclassification adjustments included in net income, net of tax	(3)	(3)
Other Comprehensive Income (Loss)	6	(6)	(2)
Comprehensive Income	$ 540	$ 433	$ 465