Accumulated Other Comprehensive Income (Loss) - After-tax Changes by Component (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (3,777)	$ (3,159)	$ (3,778)	$ (2,728)
Amounts arising during the period	196	185	166	(199)
Reclassifications from accumulated other comprehensive income	58	117	89	70
Net other comprehensive income during the period	254	302	255	(129)
Balance at end of period	(3,523)	(2,857)	(3,523)	(2,857)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(1,651)	(984)	(1,627)	(520)
Amounts arising during the period	231	268	207	(196)
Reclassifications from accumulated other comprehensive income	0	0	0	0
Net other comprehensive income during the period	231	268	207	(196)
Balance at end of period	(1,420)	(716)	(1,420)	(716)
Qualifying Derivatives Unrealized Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(14)	(5)	(7)	(7)
Amounts arising during the period	(24)	(85)	(30)	(5)
Reclassifications from accumulated other comprehensive income	25	85	24	7
Net other comprehensive income during the period	1	0	(6)	2
Balance at end of period	(13)	(5)	(13)	(5)
Equity Investees Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(1)	0	(1)	0
Amounts arising during the period	0	0	0	0
Reclassifications from accumulated other comprehensive income	1	(1)	1	(1)
Net other comprehensive income during the period	1	(1)	1	(1)
Balance at end of period	0	(1)	0	(1)
Defined Benefit Plans Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(8)	(6)	(8)	(6)
Amounts arising during the period	0	0	0	0
Reclassifications from accumulated other comprehensive income	1	1	1	1
Net other comprehensive income during the period	1	1	1	1
Balance at end of period	(7)	(5)	(7)	(5)
Defined Benefit Plans Actuarial Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(2,103)	(2,164)	(2,135)	(2,195)
Amounts arising during the period	(11)	2	(11)	2
Reclassifications from accumulated other comprehensive income	31	32	63	63
Net other comprehensive income during the period	20	34	52	65
Balance at end of period	(2,083)	(2,130)	(2,083)	(2,130)
LG And E And KU Energy LLC [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(68)	(45)	(70)	(46)
Amounts arising during the period	(11)	1	(11)	1
Reclassifications from accumulated other comprehensive income	2	1	4	2
Net other comprehensive income during the period	(9)	2	(7)	3
Balance at end of period	(77)	(43)	(77)	(43)
LG And E And KU Energy LLC [Member] | Equity Investees Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	0	0	(1)	0
Amounts arising during the period	0	0	0	0
Reclassifications from accumulated other comprehensive income	0	(1)	1	(1)
Net other comprehensive income during the period	0	(1)	1	(1)
Balance at end of period	0	(1)	0	(1)
LG And E And KU Energy LLC [Member] | Defined Benefit Plans Prior Service Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(8)	(10)	(8)	(10)
Amounts arising during the period	0	0	0	0
Reclassifications from accumulated other comprehensive income	1	1	1	1
Net other comprehensive income during the period	1	1	1	1
Balance at end of period	(7)	(9)	(7)	(9)
LG And E And KU Energy LLC [Member] | Defined Benefit Plans Actuarial Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(60)	(35)	(61)	(36)
Amounts arising during the period	(11)	1	(11)	1
Reclassifications from accumulated other comprehensive income	1	1	2	2
Net other comprehensive income during the period	(10)	2	(9)	3
Balance at end of period	$ (70)	$ (33)	$ (70)	$ (33)