Retirement Benefits and Trusteed Assets (OPEB - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts recognized in Regulatory assets
Regulatory assets	$ 4,257	$ 4,176
Other postretirement benefit plan
Change in accumulated postretirement benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	1,751	1,645
Service cost	26	22	$ 27
Interest cost	56	70	69
Plan amendments	0	(53)
Actuarial loss	54	153
Benefits paid	(80)	(86)
Projected/Accumulated postretirement benefit obligation, end of year	1,807	1,751	1,645
Change in plan assets
Plan assets at fair value, beginning of year	1,819	1,689
Actual return on plan assets	220	215
Benefits paid	(79)	(85)
Plan assets at fair value, end of year	1,960	1,819	1,689
Funded status	153	68
Amount recorded as:
Noncurrent assets	561	454
Current liabilities	(1)	(1)
Noncurrent liabilities	(407)	(385)
Defined benefit plans assets (liabilities)	153	68
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial gain	(7)	(8)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	(7)	(8)
Amounts recognized in Regulatory assets
Net actuarial loss	234	289
Prior service credit	(69)	(88)
Regulatory assets	165	201
DTE Electric
Amounts recognized in Regulatory assets
Regulatory assets	3,563	3,453
DTE Electric | Other postretirement benefit plan
Change in accumulated postretirement benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	1,337	1,247
Service cost	20	16	20
Interest cost	43	53	53
Plan amendments	0	(33)
Actuarial loss	31	118
Benefits paid	(62)	(64)
Projected/Accumulated postretirement benefit obligation, end of year	1,369	1,337	1,247
Change in plan assets
Plan assets at fair value, beginning of year	1,236	1,158
Actual return on plan assets	145	141
Benefits paid	(61)	(63)
Plan assets at fair value, end of year	1,320	1,236	$ 1,158
Funded status	(49)	(101)
Amount recorded as:
Noncurrent assets	335	266
Current liabilities	0	0
Noncurrent liabilities	(384)	(367)
Defined benefit plans assets (liabilities)	(49)	(101)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial gain	0	0
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	0	0
Amounts recognized in Regulatory assets
Net actuarial loss	156	193
Prior service credit	(48)	(62)
Regulatory assets	$ 108	$ 131