Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Allowances for doubtful accounts receivable	$ 24	$ 28
Allowances for doubtful notes receivable	$ 16	$ 9
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares outstanding	279,200,000	277,200,000
Consumers Energy Company [Member]
Allowances for doubtful accounts receivable	$ 24	$ 28
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares outstanding	84,100,000	84,100,000