Retirement Benefits and Trusteed Assets (Tables)

9 Months Ended

Sep. 30, 2018

Defined Benefit Plan [Abstract]

Schedule of Net Periodic Benefit Costs (Credits)

The following tables detail the components of net periodic benefit costs (credits) for other postretirement benefits for DTE Electric:

	Other Postretirement Benefits
	2018			2017
Three Months Ended September 30,	(In millions)
Service cost	$	5		$	5
Interest cost	13			14
Expected return on plan assets	(25		)	(23		)
Amortization of:
Net actuarial loss	3			2
Prior service credit	—			(2		)
Net periodic benefit credit	$	(4	)	$	(4	)

	Other Postretirement Benefits
	2018			2017
Nine Months Ended September 30,	(In millions)
Service cost	$	15		$	15
Interest cost	40			42
Expected return on plan assets	(74		)	(68		)
Amortization of:
Net actuarial loss	7			6
Prior service credit	—			(7		)
Net periodic benefit credit	$	(12	)	$	(12	)

The following tables detail the components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits for DTE Energy:

	Pension Benefits						Other Postretirement Benefits
	2018			2017			2018			2017
Three Months Ended September 30,	(In millions)
Service cost	$	24		$	22		$	6		$	7
Interest cost	51			53			18			18
Expected return on plan assets	(82		)	(78		)	(36		)	(33		)
Amortization of:
Net actuarial loss	43			46			3			3
Prior service cost (credit)	—			1			—			(3		)
Net periodic benefit cost (credit)	$	36		$	44		$	(9	)	$	(8	)

	Pension Benefits						Other Postretirement Benefits
	2018			2017			2018			2017
Nine Months Ended September 30,	(In millions)
Service cost	$	74		$	69		$	20		$	20
Interest cost	151			160			52			55
Expected return on plan assets	(247		)	(233		)	(107		)	(98		)
Amortization of:
Net actuarial loss	132			132			8			10
Prior service cost (credit)	—			1			—			(10		)
Net periodic benefit cost (credit)	$	110		$	129		$	(27	)	$	(23	)

Schedule of Defined Benefit Plans Disclosures

During 2018, DTE Energy contributed the following amounts of DTE Energy common stock to the DTE Energy Company Affiliates Employee Benefit Plans Master Trust:

Date	Number of Shares	Price per Share	Amount
			(In millions)
March 7, 2018	1,751,401	$99.92	$	175