Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net income	$ 125	$ 68	$ 289	$ 270
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	1	1	2
Amortization of prior service credit, net of tax	(1)		(1)
Investments
Unrealized gain (loss) on investments, net of tax		(1)		(1)
Other Comprehensive Income (Loss)				1
Comprehensive Income	125	68	289	271
Comprehensive Income Attributable to Noncontrolling Interest	1	1	1	1
Comprehensive Income Attributable to CMS Energy	124	67	288	270
Consumers Energy Company [Member]
Net income	132	84	304	299
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax		1		2
Investments
Unrealized gain (loss) on investments, net of tax	2	(2)	5	(2)
Reclassification adjustments included in net income, net of tax				(5)
Other Comprehensive Income (Loss)	2	(1)	5	(5)
Comprehensive Income Attributable to CMS Energy	$ 134	$ 83	$ 309	$ 294