Financings (Short-term Borrowings) (Details) (Consumers Energy Company [Member], Short-term Borrowings [Member], USD $) In Millions	9 Months Ended
	Sep. 30, 2011
Consumers Energy Company [Member] | Short-term Borrowings [Member]
Accounts receivable sales facility, maximum borrowing capacity	$ 250
Accounts receivable sales facility, current borrowing capacity	250
Maximum outstanding during the period	$ 0