Fair Value Measurements and Credit Concentration (Net Asset and Liability Measured on Recurring Basis Level 3 Unobservable Inputs Reconciliation Rollforward) (Details) (Recurring [Member], Level 3 [Member], USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Reconciliation of net assets and liabilities
Balance at beginning of period	$ 90,000,000	$ 62,000,000	$ 43,000,000		$ 39,000,000
Total realized/unrealized gains (losses)
Included in earnings	(84,000,000)	18,000,000	(147,000,000)		23,000,000
Included in OCI	0	(2,000,000)	(1,000,000)	[1]	1,000,000	[1]
Purchases	0		(6,000,000)
Sales	64,000,000	0	61,000,000		(2,000,000)
Settlements	(37,000,000)	(2,000,000)	82,000,000		1,000,000
Transfers into Level 3		(7,000,000)			7,000,000
Transfers out of Level 3	0	(3,000,000)	1,000,000		(3,000,000)
Balance at end of period	33,000,000	66,000,000	33,000,000		66,000,000
Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	74,000,000	40,000,000	24,000,000		22,000,000
Total realized/unrealized gains (losses)
Included in earnings	(84,000,000)	18,000,000	(147,000,000)		23,000,000
Included in OCI	0	0	0		0
Purchases	0		(6,000,000)
Sales	67,000,000	0	67,000,000		(2,000,000)
Settlements	(37,000,000)	(2,000,000)	82,000,000		1,000,000
Transfers into Level 3		(7,000,000)			1,000,000
Transfers out of Level 3	0	(2,000,000)	0		2,000,000
Balance at end of period	20,000,000	47,000,000	20,000,000		47,000,000
Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	16,000,000	19,000,000	19,000,000		16,000,000
Total realized/unrealized gains (losses)
Included in earnings	0	0	0		0
Included in OCI	0	0	0		0
Purchases	0		0
Sales	(3,000,000)	0	(6,000,000)		0
Settlements	0	0	0		0
Transfers into Level 3		0			3,000,000
Transfers out of Level 3	0	0	0		0
Balance at end of period	13,000,000	19,000,000	13,000,000		19,000,000
Cross Currency Swaps [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	0	3,000,000	0		1,000,000
Total realized/unrealized gains (losses)
Included in earnings	0	0	0		0
Included in OCI	0	(2,000,000)	(1,000,000)	[1]	1,000,000	[1]
Purchases	0		0
Sales	0	0	0		0
Settlements	0	0	0		0
Transfers into Level 3		0			3,000,000
Transfers out of Level 3	0	(1,000,000)	1,000,000		(5,000,000)
Balance at end of period	0	0	0		0
PPL Energy Supply LLC [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	87,000,000	56,000,000	40,000,000		35,000,000
Total realized/unrealized gains (losses)
Included in earnings	(84,000,000)	18,000,000	(147,000,000)		23,000,000
Purchases	0		(6,000,000)
Sales	64,000,000	0	61,000,000		(2,000,000)
Settlements	(37,000,000)	(2,000,000)	82,000,000		1,000,000
Transfers into Level 3		(7,000,000)			4,000,000
Transfers out of Level 3		(2,000,000)			2,000,000
Balance at end of period	30,000,000	63,000,000	30,000,000		63,000,000
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	74,000,000	40,000,000	24,000,000		22,000,000
Total realized/unrealized gains (losses)
Included in earnings	(84,000,000)	18,000,000	(147,000,000)		23,000,000
Purchases	0		(6,000,000)
Sales	67,000,000	0	67,000,000		(2,000,000)
Settlements	(37,000,000)	(2,000,000)	82,000,000		1,000,000
Transfers into Level 3		(7,000,000)			1,000,000
Transfers out of Level 3		(2,000,000)			2,000,000
Balance at end of period	20,000,000	47,000,000	20,000,000		47,000,000
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	13,000,000	16,000,000	16,000,000		13,000,000
Total realized/unrealized gains (losses)
Included in earnings	0	0	0		0
Purchases	0		0
Sales	(3,000,000)	0	(6,000,000)		0
Settlements	0	0	0		0
Transfers into Level 3		0			3,000,000
Transfers out of Level 3		0			0
Balance at end of period	$ 10,000,000	$ 16,000,000	$ 10,000,000		$ 16,000,000

[1] "Energy Commodities, net" and "Cross-Currency Swaps" are included in "Qualifying derivatives" and "Auction Rate Securities" are included in "Available-for-sale securities" on the Statements of Comprehensive Income.