Retirement Benefits (Tables)

9 Months Ended

Sep. 30, 2016

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Net Benefit Costs

In Millions
	DB Pension Plan												OPEB Plan
	Three Months Ended						Nine Months Ended						Three Months Ended						Nine Months Ended
September 30	2016			2015			2016			2015			2016			2015			2016			2015
CMS Energy, including Consumers
Net periodic cost (credit)
Service cost		$	10		$	13		$	31		$	37		$	5		$	7		$	14		$	19
Interest expense			21			26			64			77			12			14			35			43
Expected return on plan assets			(36)			(35)			(110)			(104)			(22)			(23)			(65)			(68)
Amortization of:
Net loss			17			22			52			67			5			5			16			16
Prior service cost (credit)			1			-			3			1			(10)			(10)			(31)			(31)
Net periodic cost (credit)		$	13		$	26		$	40		$	78		$	(10)		$	(7)		$	(31)		$	(21)
Consumers
Net periodic cost (credit)
Service cost		$	11		$	12		$	31		$	36		$	4		$	7		$	13		$	19
Interest expense			20			25			62			74			12			14			34			42
Expected return on plan assets			(35)			(34)			(107)			(101)			(20)			(22)			(60)			(65)
Amortization of:
Net loss			16			22			50			66			5			6			16			17
Prior service cost (credit)			1			-			3			1			(10)			(10)			(30)			(30)
Net periodic cost (credit)		$	13		$	25		$	39		$	76		$	(9)		$	(5)		$	(27)		$	(17)

Consumers Energy Company [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Net Benefit Costs

In Millions
	DB Pension Plan												OPEB Plan
	Three Months Ended						Nine Months Ended						Three Months Ended						Nine Months Ended
September 30	2016			2015			2016			2015			2016			2015			2016			2015
CMS Energy, including Consumers
Net periodic cost (credit)
Service cost		$	10		$	13		$	31		$	37		$	5		$	7		$	14		$	19
Interest expense			21			26			64			77			12			14			35			43
Expected return on plan assets			(36)			(35)			(110)			(104)			(22)			(23)			(65)			(68)
Amortization of:
Net loss			17			22			52			67			5			5			16			16
Prior service cost (credit)			1			-			3			1			(10)			(10)			(31)			(31)
Net periodic cost (credit)		$	13		$	26		$	40		$	78		$	(10)		$	(7)		$	(31)		$	(21)
Consumers
Net periodic cost (credit)
Service cost		$	11		$	12		$	31		$	36		$	4		$	7		$	13		$	19
Interest expense			20			25			62			74			12			14			34			42
Expected return on plan assets			(35)			(34)			(107)			(101)			(20)			(22)			(60)			(65)
Amortization of:
Net loss			16			22			50			66			5			6			16			17
Prior service cost (credit)			1			-			3			1			(10)			(10)			(30)			(30)
Net periodic cost (credit)		$	13		$	25		$	39		$	76		$	(9)		$	(5)		$	(27)		$	(17)