Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net Income	$ 94	$ 127	$ 382	$ 352
Retirement Benefits Liability
Net gain arising during the period, net of tax		10		10
Prior service credit adjustment, net of tax		5		5
Amortization of net actuarial loss, net of tax	1	1	2	3
Amortization of prior service credit, net of tax	(1)		(1)
Investments
Unrealized gain (loss) on investments, net of tax		1		(2)
Derivative Instruments
Reclassification adjustments included in net income, net of tax			1
Other Comprehensive Income (Loss)		17	2	16
Comprehensive Income	94	144	384	368
Comprehensive Income Attributable to Noncontrolling Interest		1	1	2
Comprehensive Income Attributable to CMS Energy	94	143	383	366
Consumers Energy Company [Member]
Net Income	119	153	449	415
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1		2	2
Investments
Unrealized gain (loss) on investments, net of tax	(1)		2
Reclassification adjustments included in net income, net of tax				(3)
Derivative Instruments
Other Comprehensive Income (Loss)			4	(1)
Comprehensive Income	$ 119	$ 153	$ 453	$ 414