Consolidated Statements Of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Amortization of net actuarial loss, tax	$ 1	$ 1	$ 1	$ 1
Reclassification adjustments included in net income (loss), tax
Unrealized gain (loss) on investments, tax expense (tax benefit)
Consumers Energy Company [Member]
Amortization of net actuarial loss, tax		1		1
Unrealized gain (loss) on investments, tax expense (tax benefit)	1	1	2	1
Reclassification adjustments included in net income, tax				$ (1)