Schedule I - Condensed Financial Information of Registrant (Condensed Statements Of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows from Operating Activities
Net cash provided by operating activities	$ 1,819	$ 1,276	$ 1,790
Cash Flows from Investing Activities
Net cash used in investing activities	(1,233)	(2,867)	(2,816)
Cash Flows from Financing Activities
Proceeds from issuance of debt	335	3,179	2,151
Issuance of common stock, net of issuance costs	26	253	12
Issuance of preferred stock, net of issuance costs	224	0	0
Retirement of long-term debt	(235)	(2,010)	(1,285)
Debt prepayment costs	0	(59)	(8)
Payment of dividends on common and preferred stock	(509)	(467)	(436)
Net cash provided by (used in) financing activities	(295)	1,619	1,008
Net Increase (Decrease) in Cash and Cash Equivalents, Including Restricted Amounts	291	28	(18)
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	185	157	175
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	476	185	157
CMS Energy
Cash Flows from Operating Activities
Net cash provided by operating activities	1,549	507	697
Cash Flows from Investing Activities
Investment in subsidiaries	(581)	(657)	(683)
Increase in notes receivable – intercompany	(83)	(307)	0
Net cash used in investing activities	(664)	(964)	(683)
Cash Flows from Financing Activities
Proceeds from issuance of debt	0	1,225	1,158
Issuance of common stock, net of issuance costs	26	253	12
Issuance of preferred stock, net of issuance costs	224	0	0
Retirement of long-term debt	(200)	(425)	(738)
Debt prepayment costs	0	(16)	0
Payment of dividends on common and preferred stock	(507)	(465)	(434)
Debt issuance costs and financing fees	(10)	(10)	(18)
Change in notes payable – intercompany	(28)	(105)	6
Net cash provided by (used in) financing activities	(495)	457	(14)
Net Increase (Decrease) in Cash and Cash Equivalents, Including Restricted Amounts	390	0	0
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	0	0	0
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	$ 390	$ 0	$ 0