Consolidated Statements Of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net gain (loss) arising during the period, tax		$ 6		$ 6
Tax on prior service credit adjustment		3		3
Amortization of net actuarial loss, tax		1	1	2
Amortization of prior service credit, tax		(1)		(1)
Reclassification adjustments included in net income (loss), tax
Unrealized gain (loss) on investments, tax expense (tax benefit)		(1)		(1)
Consumers Energy Company [Member]
Amortization of net actuarial loss, tax		1		1
Unrealized gain (loss) on investments, tax expense (tax benefit)	(1)		1
Reclassification adjustments included in net income, tax				$ (1)