Accumulated Other Comprehensive Income (Loss) - After-tax Changes by Component (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (4,220)	$ (4,358)
Amounts arising during the period	273	(53)
Reclassifications from AOCI	65	45
Net OCI during the period	338	(8)
Balance at end of period	(3,882)	(4,366)
Foreign currency translation adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(1,158)	(1,425)
Amounts arising during the period	303	(61)
Reclassifications from AOCI	0	0
Net OCI during the period	303	(61)
Balance at end of period	(855)	(1,486)
Unrealized gains (losses) on qualifying derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	0	(5)
Amounts arising during the period	(30)	8
Reclassifications from AOCI	25	(3)
Net OCI during the period	(5)	5
Balance at end of period	(5)	0
Defined benefit plans Prior service costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(16)	(18)
Amounts arising during the period	0	0
Reclassifications from AOCI	0	1
Net OCI during the period	0	1
Balance at end of period	(16)	(17)
Defined benefit plans Actuarial gain (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(3,046)	(2,910)
Amounts arising during the period	0	0
Reclassifications from AOCI	40	47
Net OCI during the period	40	47
Balance at end of period	(3,006)	(2,863)
Accumulated Defined Benefit Plans Net | WPD
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at end of period	2,800
LG And E And KU Energy LLC [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net OCI during the period	$ 3	$ 1