Revenue (Components Of Accounts Receivable And Accrued Revenue) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Accounts receivable and accrued revenue from contracts with customers	$ 808	$ 844
Other accounts receivable	194	188
Total accounts receivable and accrued revenue	1,002	1,032
Consumers Energy Company [Member]
Accounts receivable and accrued revenue from contracts with customers	802	838
Other accounts receivable	56	47
Total accounts receivable and accrued revenue	858	885
Enterprises [Member]
Accounts receivable and accrued revenue from contracts with customers	$ 6	$ 6