Plant, Property, and Equipment (Public Utilities, Allowance for Funds Used During Construction, Schedule of Composite Rate Table) (Details)	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consumers Energy Company [Member]
AFUDC capitalization rate	7.10%	7.20%	7.30%

Disclosure of the composite rate of allowance for funds used during construction (AFUDC). The composite AFUDC rate is the average of the electric, gas, and common rates used during the period.

No definition available.

Name:	cms_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCompositeRate
Namespace Prefix:	cms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration