Regulatory Matters (Schedule of the Components of PSCR and GCR Over/(Under) Recoveries) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accrued gas revenue		$ 27
Accrued rate refunds	$ 26	6
Consumers Energy Company [Member]
Accrued gas revenue		27
Accrued rate refunds	$ 26	$ 6

Carrying amount as of the balance sheet date of capitalized fuel costs of a regulated entity that are expected to be recoverable through rate adjustments within one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6499739&loc=d3e43603-110378

Name:	us-gaap_DeferredFuelCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant