Cash And Cash Equivalents (Schedule Of Cash And Cash Equivalents, Including Restricted Amounts) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 153	$ 32
Restricted cash and cash equivalents	18	17
Cash and cash equivalents, including restricted amounts	292	185	$ 1,604	$ 157
Discontinued Operations, Held-for-sale
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	121	136
Consumers Energy Company
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	52	20
Restricted cash and cash equivalents	16	15
Cash and cash equivalents, including restricted amounts	$ 68	$ 35	$ 1,229	$ 28