Income Taxes (Details)		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
U.S. federal income tax rate		35.00%	35.00%
State and local income taxes, net of federal effect		4.10%	4.80%
Accelerated flow-through of regulatory tax benefits		(4.70%)	(4.90%)
Employee share-based awards	[1]	(2.20%)
Other, net		(1.10%)	(1.80%)
Effective tax rate		31.10%	33.10%
Consumers Energy Company [Member]
U.S. federal income tax rate		35.00%	35.00%
State and local income taxes, net of federal effect		4.40%	4.70%
Accelerated flow-through of regulatory tax benefits		(4.20%)	(4.40%)
Employee share-based awards	[1]	(2.00%)
Other, net		(0.90%)	(1.50%)
Effective tax rate		32.30%	33.80%

[1] CMS Energy and Consumers elected to adopt ASU 2016-09, Improvements to Employee Share-Based Payment Accounting, as of January 1, 2016. For further details on the implementation of this standard, see Note 1, New Accounting Standards.