Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Allowances for doubtful accounts receivable	$ 28	$ 40
Allowances for doubtful notes receivable	$ 9	$ 8
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares outstanding	277,200,000	275,200,000
Consumers Energy Company [Member]
Allowances for doubtful accounts receivable	$ 28	$ 39
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares outstanding	84,100,000	84,100,000