Derivative Instruments and Hedging Activities (Commodity Volumetric Activity) (Details)	Sep. 30, 2011 MW		Mar. 31, 2011 MW
Commodity Volumetric Activity - Sales of Baseload Generation (Numeric) [Abstract]
Baseload generation fleet capacity (in MW)	7,357		0
Commodity Volumetric Activity - Optimization of Intermediate and Peaking Generation (Numeric) [Abstract]
Intermediate and peaking generation fleet capacity (in MW)	3,395
Oil Swap [Member] | 2011 [Member] | Thousand of Barrels [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(21)	[1]
Oil Swap [Member] | 2012 [Member] | Thousand of Barrels [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	651
Oil Swap [Member] | 2013 [Member] | Thousand of Barrels [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	540	[2]
Oil Swap [Member] | Future Years [Member] | Thousand of Barrels [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	120
Net Power Sales [Member] | Non-option Contracts [Member] | 2011 [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(1,127)	[1],[3]
Net Power Sales [Member] | Non-option Contracts [Member] | 2012 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(2,006)	[3]
Net Power Sales [Member] | Non-option Contracts [Member] | 2013 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(1,224)	[3],[4]
Net Power Sales [Member] | Non-option Contracts [Member] | Future Years [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(1,632)
Net Fuel Purchases [Member] | Non-option Contracts [Member] | 2011 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	12.0	[1],[3]
Net Fuel Purchases [Member] | Non-option Contracts [Member] | 2012 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	13.5	[3]
Net Fuel Purchases [Member] | Non-option Contracts [Member] | 2013 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	8.2	[3],[4]
Net Fuel Purchases [Member] | Non-option Contracts [Member] | Future Years [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	11.0
Energy Sales Contracts [Member] | 2011 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(4,319)	[1],[5]
Energy Sales Contracts [Member] | 2012 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(13,074)	[5]
Energy Sales Contracts [Member] | 2013 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(5,325)	[5]
Related Energy Supply Contracts [Member] | Energy Purchases [Member] | 2011 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	2,923	[1],[5]
Related Energy Supply Contracts [Member] | Energy Purchases [Member] | 2012 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	7,425	[5]
Related Energy Supply Contracts [Member] | Energy Purchases [Member] | 2013 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	645	[5]
Related Energy Supply Contracts [Member] | Volumetric Hedges [Member] | 2011 [Member] | GWh [Member]
Volumes of (Sales)/Purchase Contracts, Excluding FTRs, Basis and Capacity Contracts [Abstract]
Volumetric hedge volumes (in units)	90	[1],[5],[6]
Related Energy Supply Contracts [Member] | Volumetric Hedges [Member] | 2012 [Member] | GWh [Member]
Volumes of (Sales)/Purchase Contracts, Excluding FTRs, Basis and Capacity Contracts [Abstract]
Volumetric hedge volumes (in units)	312	[5],[6]
Related Energy Supply Contracts [Member] | Volumetric Hedges [Member] | 2013 [Member] | GWh [Member]
Volumes of (Sales)/Purchase Contracts, Excluding FTRs, Basis and Capacity Contracts [Abstract]
Volumetric hedge volumes (in units)	43	[5],[6]
Related Energy Supply Contracts [Member] | Generation Supply [Member] | 2011 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	1,265	[1],[5]
Related Energy Supply Contracts [Member] | Generation Supply [Member] | 2012 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	5,457	[5]
Related Energy Supply Contracts [Member] | Generation Supply [Member] | 2013 [Member] | GWh [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	4,478	[5]
Retail Gas Sales Contracts [Member] | 2011 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(2.6)	[1]
Retail Gas Sales Contracts [Member] | 2012 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(9.1)
Retail Gas Sales Contracts [Member] | 2013 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(0.5)
Retail Gas Purchase Contracts [Member] | 2011 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	2.5	[1]
Retail Gas Purchase Contracts [Member] | 2012 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	9.1
Retail Gas Purchase Contracts [Member] | 2013 [Member] | Bcf [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	0.5
FTRs [Member] | 2011 [Member] | GWh [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
FTRs commodity positions (in GWh)	9,720	[1]
FTRs [Member] | 2012 [Member] | GWh [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
FTRs commodity positions (in GWh)	15,008
FTRs [Member] | 2013 [Member] | GWh [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
FTRs commodity positions (in GWh)	0
Power Basis Positions [Member] | 2011 [Member] | GWh [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
Power basis commodity positions (in GWh)	(4,022)	[1]
Power Basis Positions [Member] | 2012 [Member] | GWh [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
Power basis commodity positions (in GWh)	(10,828)
Power Basis Positions [Member] | 2013 [Member] | GWh [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
Power basis commodity positions (in GWh)	(987)	[7]
Power Basis Positions [Member] | Future Years [Member] | GWh [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
Power basis commodity positions (in GWh)	364
Gas Basis Positions [Member] | 2011 [Member] | Bcf [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
Gas basis commodity positions (in Bcf)	7.7	[1]
Gas Basis Positions [Member] | 2012 [Member] | Bcf [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
Gas basis commodity positions (in Bcf)	12.9
Gas Basis Positions [Member] | 2013 [Member] | Bcf [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
Gas basis commodity positions (in Bcf)	(1.0)	[7]
Gas Basis Positions [Member] | Future Years [Member] | Bcf [Member]
Volumes of Derivative FTR and basis (sales)/purchase contracts [Abstract]
Gas basis commodity positions (in Bcf)	(2.0)
Capacity [Member] | 2011 [Member] | MW-months [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(2,944)	[1],[8],[9]
Capacity [Member] | 2012 [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(6,422)
Capacity [Member] | 2013 [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(1,384)	[9]
Capacity [Member] | Future Years [Member] | MW-months [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Notional amount (in units)	(253)
2011 [Member] | GWh [Member]
Expected Sales, in GWh, of Baseload Generation [Abstract]
Expected sales of baseload generation (in GWh)	13,575	[8]
2011 [Member] | Percent Unit [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Derivative sales, as percentage of expected baseload generation	90.00%	[1],[10]
Total power sales, as percentage of expected baseload generation	100.00%	[1],[11]
Coal fuel purchases, as percentage of expected baseload generation	100.00%	[1],[12]
Nuclear fuel purchases, as percentage of expected baseload generation (in hundredths)	100.00%	[1],[12]
2012 [Member] | GWh [Member]
Expected Sales, in GWh, of Baseload Generation [Abstract]
Expected sales of baseload generation (in GWh)	54,675
2012 [Member] | Percent Unit [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Derivative sales, as percentage of expected baseload generation	92.00%	[10]
Total power sales, as percentage of expected baseload generation	91.00%	[11]
Coal fuel purchases, as percentage of expected baseload generation	96.00%	[12]
Nuclear fuel purchases, as percentage of expected baseload generation (in hundredths)	100.00%	[12]
2013 [Member] | GWh [Member]
Expected Sales, in GWh, of Baseload Generation [Abstract]
Expected sales of baseload generation (in GWh)	54,364
2013 [Member] | Percent Unit [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Derivative sales, as percentage of expected baseload generation	63.00%	[10],[13]
Total power sales, as percentage of expected baseload generation	72.00%	[11],[13]
Coal fuel purchases, as percentage of expected baseload generation	89.00%	[12],[13]
Nuclear fuel purchases, as percentage of expected baseload generation (in hundredths)	100.00%	[12],[13]
Future Years [Member]
Percentage Of Expected Baseload Generation Sales [Abstract]
Volumes for sales contracts that deliver in future years (in GWh)	3,050

[1] Represents the balance of the current year.

[2] Volumes (in thousands of barrels) for derivative contracts used in support of this strategy that deliver in future periods total 120.

[3] Included in these volumes are non-options and exercised option contracts that converted to non-option derivative contracts. Volumes associated with option contracts are not significant.

[4] Volumes for derivative contracts used in support of these strategies that deliver in future periods total (1,632) GWh and 11.0 Bcf.

[5] Includes NPNS and contracts that are not derivatives, which receive accrual accounting.

[6] PPL Energy Supply uses power and gas options, swaps and futures to hedge the volumetric risk associated with full-requirement sales contracts since the demand for power varies hourly. Volumes for option contracts factor in the probability of an option being exercised and may be less than the notional amount of the option.

[7] Volumes that deliver in future periods are 364 GWh and (2.0) Bcf.

[8] Represents expected sales for the balance of the current year.

[9] Volumes that deliver in future periods are (253) MW-months.

[10] Excludes non-derivative contracts and contracts that qualify for NPNS. Volumes for option contracts factor in the probability of an option being exercised and may be less than the notional amount of the option.

[11] Amount represents derivative and non-derivative contracts. Volumes for option contracts factor in the probability of an option being exercised and may be less than the notional amount of the option. Percentages are based on fixed-price contracts only.

[12] Coal and nuclear contracts receive accrual accounting treatment, as they are not derivative contracts. Percentages are based on both fixed- and variable-priced contracts.

[13] Volumes for derivative sales contracts that deliver in future periods total 3,050 GWh.