Cash And Cash Equivalents (Schedule Of Cash And Cash Equivalents, Including Restricted Amounts) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 834	$ 140
Restricted cash and cash equivalents	27	17
Cash and cash equivalents, including restricted amounts	861	157	$ 267	$ 175
Consumers Energy Company
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	604	11
Restricted cash and cash equivalents	24	17
Cash and cash equivalents, including restricted amounts	$ 628	$ 28	$ 64	$ 56