Risk Management and Fair Values (Details 3) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Reconciliation of changes in the net assets (liabilities) for the fair value of derivatives classified as Level 3 in the fair value hierarchy
Balance as of Beginning of period	$ 98	$ 297	$ 197	$ 200
Unrealized gains (losses) from price changes	3	124	(33)	316
Unrealized gains on originations	17	6	15	14
Realized losses on settlements	(48)	(43)	(109)	(146)
Balance as of September 30	$ 70	$ 384	$ 70	$ 384