Regulatory Matters (Schedule of GCR Reconciliation Filing Pending with the MPSC) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Consumers Energy Company [Member]	Dec. 31, 2012 Consumers Energy Company [Member]	Dec. 31, 2011 Consumers Energy Company [Member]	Mar. 31, 2013 Gas Cost Recover (GCR) [Member] Consumers Energy Company [Member]	Mar. 31, 2012 Gas Cost Recover (GCR) [Member] Consumers Energy Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Date Of Filing							June 2013
Net Over/(Under) Recovery, Including Interest, Requested by Consumers							$ (22)
Cost of gas sold	$ 1,228	$ 1,150	$ 1,512	$ 1,187	$ 1,110	$ 1,438	$ 900	$ 900