Cash And Cash Equivalents (Schedule Of Cash And Cash Equivalents, Including Restricted Amounts) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 519	$ 140
Restricted cash and cash equivalents	39	17
Cash and cash equivalents, including restricted amounts	558	157	$ 433	$ 175
Consumers Energy Company
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	199	11
Restricted cash and cash equivalents	24	17
Cash and cash equivalents, including restricted amounts	$ 223	$ 28	$ 284	$ 56