Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net income	$ 164	$ 202
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax		1
Investments
Other Comprehensive Income (Loss)		1
Comprehensive Income Attributable to CMS Energy	164	203
Consumers Energy Company [Member]
Net income	172	215
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax		1
Investments
Unrealized gain on investments, net of tax	3
Reclassification adjustments included in net income, net of tax		(5)
Other Comprehensive Income (Loss)	3	(4)
Comprehensive Income Attributable to CMS Energy	$ 175	$ 211