Plant, Property, and Equipment (Public Utilities, Allowance for Funds Used During Construction, Schedule of Composite Rate Table) (Details) (Consumers Energy Company [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Consumers Energy Company [Member]
Public Utilities Allowance For Funds Used During Construction Composite Rate	7.20%	7.30%	7.30%