Plant, Property, and Equipment (Schedule of Capital Leased Asssets) (Details) (Consumers Energy Company [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Consumers Energy Company [Member]
Balance at beginning of period	$ 285	$ 280
Capital Leased Assets, Gross, Additions	12	9
Capital Leased Assets, Gross, Disposals and Transfers	(6)	(4)
Balance at end of period	291	285
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	$ 124	$ 108