Consolidated Balance Sheets (Parenthetical) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Allowances for doubtful accounts receivable	$ 25	$ 25
Allowances for doubtful notes receivable	5	5
Common stock, shares authorized	350.0	350.0
Common stock, shares outstanding	252.0	249.6
Consumers Energy Company [Member]
Allowances for doubtful accounts receivable	$ 23	$ 23
Common stock, shares authorized	125.0	125.0
Common stock, shares outstanding	84.1	84.1