Fair Value Measurements and Credit Concentration (Net Asset and Liability Measured on Recurring Basis Level 3 Unobservable Inputs Reconciliation Rollforward) (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Reconciliation of net assets and liabilities
Balance at beginning of period	$ 39		$ 41
Total realized/unrealized gains (losses)
Included in earnings	(8)		18
Included in OCI	3	[1]	4	[1]
Settlements	(1)		(6)
Transfers into Level 3	1
Transfers out of Level 3	(4)		(11)
Balance at end of period	30		46
Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	22		13
Total realized/unrealized gains (losses)
Included in earnings	(8)		18
Included in OCI			2	[1]
Settlements	(1)		(6)
Transfers into Level 3	1
Transfers out of Level 3			(8)
Balance at end of period	14		19
Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	16		24
Total realized/unrealized gains (losses)
Included in earnings
Included in OCI
Settlements
Transfers into Level 3
Transfers out of Level 3
Balance at end of period	16		24
Cross Currency Swaps [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	1		4
Total realized/unrealized gains (losses)
Included in earnings
Included in OCI	3	[1]	2	[1]
Settlements
Transfers into Level 3
Transfers out of Level 3	(4)		(3)
Balance at end of period			3
PPL Energy Supply LLC [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	35		32
Total realized/unrealized gains (losses)
Included in earnings	(8)		18
Included in OCI			2	[1]
Settlements	(1)		(6)
Transfers into Level 3	1
Transfers out of Level 3			(8)
Balance at end of period	27		38
PPL Energy Supply LLC [Member] | Energy Commodities, Net [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	22		13
Total realized/unrealized gains (losses)
Included in earnings	(8)		18
Included in OCI			2	[1]
Settlements	(1)		(6)
Transfers into Level 3	1
Transfers out of Level 3			(8)
Balance at end of period	14		19
PPL Energy Supply LLC [Member] | Auction Rate Securities [Member]
Reconciliation of net assets and liabilities
Balance at beginning of period	13		19
Total realized/unrealized gains (losses)
Included in earnings
Included in OCI
Settlements
Transfers into Level 3
Transfers out of Level 3
Balance at end of period	$ 13		$ 19

[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.