Financings And Capitalization (Major Long-Term Debt Transactions) (Details) - CMS Energy [Member]	6 Months Ended
Jun. 30, 2016 USD ($)
Debt Instrument [Line Items]
Principal Balance	$ 300,000,000
Senior Notes 3.000% Due May 2026 [Member]
Debt Instrument [Line Items]
Principal Balance	$ 300,000,000
Interest rate	3.00%
Debt issuance date	May 2016
Maturity date	May 2026

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant