Retirement Benefits (Tables)

9 Months Ended

Sep. 30, 2013

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Net Benefit Costs

In Millions
	Pension												OPEB
	Three Months Ended							Nine Months Ended					Three Months Ended							Nine Months Ended
	2013			2012			2013			2012			2013			2012			2013			2012
CMS Energy, including Consumers
Net periodic cost (credit)
Service cost		$	13		$	12		$	40		$	36		$	5		$	8		$	23		$	24
Interest expense			23			24			70			74			14			21			52			62
Expected return on plan    assets			(32)			(31)			(96)			(94)			(20)			(17)			(58)			(50)
Amortization of:
Net loss			24			19			72			57			3			12			24			35
Prior service    cost (credit)			1			1			3			4			(10)			(5)			(20)			(15)
Net periodic cost (credit)		$	29		$	25		$	89		$	77		$	(8)		$	19		$	21		$	56
Consumers
Net periodic cost (credit)
Service cost		$	13		$	12		$	39		$	35		$	5		$	7		$	23		$	23
Interest expense			23			24			69			72			14			20			50			60
Expected return on plan    assets			(31)			(30)			(94)			(91)			(19)			(15)			(54)			(46)
Amortization of:
Net loss			23			18			70			55			3			12			24			35
Prior service    cost (credit)			1			1			3			4			(10)			(5)			(20)			(15)
Net periodic cost (credit)		$	29		$	25		$	87		$	75		$	(7)		$	19		$	23		$	57

Consumers Energy Company [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Net Benefit Costs

In Millions
	Pension												OPEB
	Three Months Ended							Nine Months Ended					Three Months Ended							Nine Months Ended
	2013			2012			2013			2012			2013			2012			2013			2012
CMS Energy, including Consumers
Net periodic cost (credit)
Service cost		$	13		$	12		$	40		$	36		$	5		$	8		$	23		$	24
Interest expense			23			24			70			74			14			21			52			62
Expected return on plan    assets			(32)			(31)			(96)			(94)			(20)			(17)			(58)			(50)
Amortization of:
Net loss			24			19			72			57			3			12			24			35
Prior service    cost (credit)			1			1			3			4			(10)			(5)			(20)			(15)
Net periodic cost (credit)		$	29		$	25		$	89		$	77		$	(8)		$	19		$	21		$	56
Consumers
Net periodic cost (credit)
Service cost		$	13		$	12		$	39		$	35		$	5		$	7		$	23		$	23
Interest expense			23			24			69			72			14			20			50			60
Expected return on plan    assets			(31)			(30)			(94)			(91)			(19)			(15)			(54)			(46)
Amortization of:
Net loss			23			18			70			55			3			12			24			35
Prior service    cost (credit)			1			1			3			4			(10)			(5)			(20)			(15)
Net periodic cost (credit)		$	29		$	25		$	87		$	75		$	(7)		$	19		$	23		$	57