Plant, Property, and Equipment (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) MW	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Change in net plant, property, and equipment	$ 34,000,000
Payments to acquire plant	1,672,000,000	$ 1,564,000,000	$ 1,577,000,000
Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Payments to acquire plant	$ 1,656,000,000	$ 1,537,000,000	$ 1,573,000,000
Gas Fueled Electric Generating Units [Member] | Consumers Energy Company [Member]
Property, Plant and Equipment [Line Items]
Plant capacity | MW		540
Payments to acquire plant		$ 155,000,000
Goodwill		$ 0