Cash And Cash Equivalents (Schedule Of Cash And Cash Equivalents, Including Restricted Amounts) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 140	$ 153
Restricted cash and cash equivalents	17	21
Other non‑current assets	0	1
Cash and cash equivalents, including restricted amounts	157	175	$ 204	$ 257
Consumers Energy Company
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	11	39
Restricted cash and cash equivalents	17	17
Cash and cash equivalents, including restricted amounts	$ 28	$ 56	$ 65	$ 152