Purchase Obligations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Purchase Obligations [Line Items]
2012	$ 3,267
2013	2,809
2014	2,129
2015	1,935
2016	1,630
Thereafter	10,154
Unrecorded unconditional purchase obligation, total	21,924
Fuel for production
Purchase Obligations [Line Items]
2012	2,324
2013	2,053
2014	1,644
2015	1,460
2016	1,182
Thereafter	6,437
Unrecorded unconditional purchase obligation, total	15,100
Unrecorded unconditional purchase obligation, purchases	2,697	2,890	2,921
Purchased power
Purchase Obligations [Line Items]
2012	459
2013	440
2014	381
2015	391
2016	373
Thereafter	3,104
Unrecorded unconditional purchase obligation, total	5,148
Unrecorded unconditional purchase obligation, purchases	925	907	756
Term of unrecorded unconditional purchase obligation	2012 to 2032
Construction obligations
Purchase Obligations [Line Items]
2012	331
2013	216
2014	35
2015	23
2016	4
Thereafter	10
Unrecorded unconditional purchase obligation, total	619
Unrecorded unconditional purchase obligation, purchases	507	703	818
Other purchase obligations
Purchase Obligations [Line Items]
2012	153
2013	100
2014	69
2015	61
2016	71
Thereafter	603
Unrecorded unconditional purchase obligation, total	1,057
Unrecorded unconditional purchase obligation, purchases	151	124	56
PEC | Fuel for production | Conditional agreement
Purchase Obligations [Line Items]
Unrecorded unconditional purchase obligation, date range	July 2012 through May 2033
Long term contract amount, total	1,510
Long term contract amount, classified as capital lease	380
PEC | Purchased power | Other utilities
Purchase Obligations [Line Items]
2012	51
2013	52
2014	53
2015	60
2016	60
Thereafter	271
Long-term contract for purchase of electric power, MW	985
Long-term contract for purchase of electric power, share of plant output being purchased, bottom of range	33.00%
Long-term contract for purchase of electric power, share of plant output being purchased, top of range	100.00%
Long-term contract for purchase of electric power, date of contract expiration	2019 to 2022
PEC | Purchased power | Qualified facilities
Purchase Obligations [Line Items]
Long-term contract for purchase of electric power, MW	81
Long-term contract for purchase of electric power, share of plant output being purchased	100.00%
Long-term contract for purchase of electric power, date of contract expiration	various times through 2032
PEF | Purchased power | Other utilities
Purchase Obligations [Line Items]
2012	53
2013	46
2014	65
2015	65
2016	27
Long-term contract for purchase of electric power, MW	499
Long-term contract for purchase of electric power, share of plant output being purchased, bottom of range	12.00%
Long-term contract for purchase of electric power, share of plant output being purchased, top of range	25.00%
Long-term contract for purchase of electric power, date of contract expiration	2012 to 2016
PEF | Purchased power | Qualified facilities
Purchase Obligations [Line Items]
2012	313
2013	309
2014	238
2015	244
2016	273
Thereafter	2,728
Long-term contract for purchase of electric power, MW	682
Long-term contract for purchase of electric power, share of plant output being purchased	100.00%
Long-term contract for purchase of electric power, date of contract expiration	2012 to 2025
PEF | Levy | Construction obligations
Purchase Obligations [Line Items]
Long term contract amount, total	8,608
PEF | Levy | Construction obligations | Suspended long lead time equipment items
Purchase Obligations [Line Items]
Long term contract amount, total	$ 1,250