INVESTMENTS IN UNCONSOLIDATED ENTITIES (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 09, 2011	Apr. 15, 2011	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Investment In Joint Venture Disclosure [Abstract]
Distributable 2010 income of RBS Sempra Commodities LLP							$ 455
Due to RBS		(28)
Distributions from RBS Sempra Commodities LLP	98	329
Investment in RBS Sempra Commodities LLP			322		322		787	[1]
Pretax equity earnings (losses) from RBS Sempra Commodities LLP			(16)	(281)	(24)	(290)
Joint Venture Sales Of Businesses [Line Items]
Loss on impairment of RBS Sempra Commodities LLP			(16)	(305)	(16)
Loss on impairment of RBS Sempra Commodities LLP, after tax			(10)	(139)	(10)
Gain related to litigation settlement				48		48
Parent Company Member
Joint Venture Sales Of Businesses [Line Items]
Equity Method Investment Distribution Percentage			49.00%		49.00%
Rbs Member
Joint Venture Sales Of Businesses [Line Items]
Equity Method Investment Distribution Percentage			51.00%		51.00%
Fowler Ridge I I Wind Farm [Member]
Joint Venture Sales Of Businesses [Line Items]
Proceeds from return of capital						$ 180

[1] Derived from audited financial statements.