Plant, Property, and Equipment (Schedule of Finance Leases and Other Financing Obligations) (Details) - Consumers Energy Company - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Finance Leases and Other Financing Obligations, Rollforward [Roll Forward]
Balance at beginning of period	$ 336	$ 340
Additions	0	0
Net retirements and other adjustments	(4)	(4)
Balance at end of period	332	336
Finance lease accumulated amortization	$ 272	$ 254