Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2016

Defined Benefit Plan Disclosure [Line Items]

Schedule Of Net Benefit Costs

In Millions
	DB Pension Plan						OPEB Plan
Three Months Ended March 31	2016			2015			2016			2015
CMS Energy, including Consumers
Net periodic cost (credit)
Service cost		$	11		$	12		$	5		$	6
Interest expense			21			25			12			15
Expected return on plan assets			(37)			(34)			(22)			(23)
Amortization of:
Net loss			17			23			5			5
Prior service cost (credit)			1			-			(10)			(10)
Net periodic cost (credit)		$	13		$	26		$	(10)		$	(7)
Consumers
Net periodic cost (credit)
Service cost		$	10		$	12		$	4		$	6
Interest expense			21			25			11			14
Expected return on plan assets			(36)			(33)			(20)			(22)
Amortization of:
Net loss			17			22			6			6
Prior service cost (credit)			1			-			(10)			(10)
Net periodic cost (credit)		$	13		$	26		$	(9)		$	(6)

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 March 31	2016			2015			2016			2015
CMS Energy, including Consumers
Net periodic cost (credit)
Service cost		$	11		$	12		$	5		$	6
Interest expense			21			25			12			15
Expected return on plan assets			(37)			(34)			(22)			(23)
Amortization of:
Net loss			17			23			5			5
Prior service cost (credit)			1			-			(10)			(10)
Net periodic cost (credit)		$	13		$	26		$	(10)		$	(7)
Consumers
Net periodic cost (credit)
Service cost		$	10		$	12		$	4		$	6
Interest expense			21			25			11			14
Expected return on plan assets			(36)			(33)			(20)			(22)
Amortization of:
Net loss			17			22			6			6
Prior service cost (credit)			1			-			(10)			(10)
Net periodic cost (credit)		$	13		$	26		$	(9)		$	(6)