Cash And Cash Equivalents (Schedule Of Cash And Cash Equivalents, Including Restricted Amounts) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1,587	$ 140
Restricted cash and cash equivalents	17	17
Cash and cash equivalents, including restricted amounts	1,604	157	$ 334	$ 175
Consumers Energy Company
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	1,215	11
Restricted cash and cash equivalents	14	17
Cash and cash equivalents, including restricted amounts	$ 1,229	$ 28	$ 212	$ 56