Defined Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011		Sep. 30, 2012	Sep. 30, 2011		Dec. 31, 2011
Pension Benefits - U.S. [Member]
Net Periodic Defined Benefit Costs (Credits) [Line Items]
Service cost	$ 25	$ 24		$ 77	$ 71
Interest cost	55	54		165	163
Expected return on plan assets	(65)	(61)		(195)	(184)
Amortization of:
Prior service cost	6	6		18	18
Actuarial (gain) loss	11	7		32	21
Net periodic defined benefit costs (credits) prior to termination benefits	32	30		97	89
Termination benefits
Net periodic defined benefit costs (credits)	32	30		97	89
Pension Benefits - U.K. [Member]
Net Periodic Defined Benefit Costs (Credits) [Line Items]
Service cost	13	14		40	31
Interest cost	85	88		254	200
Expected return on plan assets	(115)	(103)		(340)	(243)
Amortization of:
Prior service cost	1	1		3	3
Actuarial (gain) loss	19	15		59	44
Net periodic defined benefit costs (credits) prior to termination benefits	3	15		16	35
Termination benefits		45	[1]		47	[1]
Net periodic defined benefit costs (credits)	3	60		16	82
Expected contribution to pension plans	344			344			161
Employer contributions				302
Other Postretirement Benefits - U.S. [Member]
Net Periodic Defined Benefit Costs (Credits) [Line Items]
Service cost	3	3		9	9
Interest cost	7	9		23	25
Expected return on plan assets	(6)	(6)		(17)	(17)
Amortization of:
Transition obligation				1	1
Prior service cost	1			1
Actuarial (gain) loss	1	1		3	4
Net periodic defined benefit costs (credits)	6	7		20	22
PPL Energy Supply LLC [Member]
Amortization of:
Allocated costs of defined benefit plans	10	8		29	23
PPL Energy Supply LLC [Member] | Pension Benefits - U.S. [Member]
Net Periodic Defined Benefit Costs (Credits) [Line Items]
Service cost	1	1		4	3
Interest cost	2	1		6	5
Expected return on plan assets	(2)	(2)		(7)	(6)
Amortization of:
Actuarial (gain) loss	1	1		2	2
Net periodic defined benefit costs (credits)	2	1		5	4
PPL Electric Utilities Corp [Member]
Amortization of:
Allocated costs of defined benefit plans	8	6		23	18
LG And E And KU Energy LLC [Member] | Pension Benefits - U.S. [Member]
Net Periodic Defined Benefit Costs (Credits) [Line Items]
Service cost	5	6		16	18
Interest cost	16	16		48	50
Expected return on plan assets	(17)	(16)		(52)	(48)
Amortization of:
Prior service cost	2	2		4	4
Actuarial (gain) loss	5	6		16	17
Net periodic defined benefit costs (credits)	11	14		32	41
LG And E And KU Energy LLC [Member] | Other Postretirement Benefits - U.S. [Member]
Net Periodic Defined Benefit Costs (Credits) [Line Items]
Service cost	1	1		3	3
Interest cost	3	3		7	8
Expected return on plan assets	(1)	(1)		(3)	(3)
Amortization of:
Transition obligation				1	1
Prior service cost		1		2	2
Actuarial (gain) loss				(1)
Net periodic defined benefit costs (credits)	3	4		9	11
Louisville Gas And Electric Co [Member]
Amortization of:
Allocated costs of defined benefit plans	3	5		9	13
Louisville Gas And Electric Co [Member] | Pension Benefits - U.S. [Member]
Net Periodic Defined Benefit Costs (Credits) [Line Items]
Service cost				1	1
Interest cost	4	4		11	11
Expected return on plan assets	(5)	(4)		(14)	(13)
Amortization of:
Prior service cost	1			2	1
Actuarial (gain) loss	3	3		8	9
Net periodic defined benefit costs (credits)	3	3		8	9
Kentucky Utilities Co [Member]
Amortization of:
Allocated costs of defined benefit plans	$ 4	$ 6		$ 13	$ 17

[1] In 2011, WPD Midlands recorded early retirement deficiency costs payable under applicable pension plans related to employees leaving the WPD Midlands companies. See Note 8 for additional information.