Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income	$ 553	$ 525	$ 479
Retirement Benefits Liability
Net gain (loss) arising during the period, net of tax	(8)	1	(29)
Amortization of net actuarial loss, net of tax	2	5	3
Amortization of prior service credit, net of tax	(1)	(1)	(1)
Investments
Unrealized gain (loss) on investments, net of tax	1	(3)	(1)
Other-than-temporary impairment included in net income, net of tax	3
Derivative Instruments
Reclassification adjustments included in net income, net of tax			1
Other Comprehensive Income (Loss)	(3)	2	(27)
Comprehensive Income	550	527	452
Comprehensive Income Attributable to Noncontrolling Interest	2	2	2
Comprehensive Income Attributable to CMS Energy	548	525	450
Consumers Energy Company [Member]
Net income	616	594	567
Retirement Benefits Liability
Net gain (loss) arising during the period, net of tax	(3)	3	(11)
Amortization of net actuarial loss, net of tax	1	4	2
Investments
Unrealized gain (loss) on investments, net of tax	3	(1)	4
Reclassification adjustments included in net income, net of tax		(5)
Other-than-temporary impairment included in net income, net of tax	2
Derivative Instruments
Other Comprehensive Income (Loss)	3	1	(5)
Comprehensive Income Attributable to CMS Energy	$ 619	$ 595	$ 562