Fair Value Measurement (Gains And Losses (Realized And Unrealized) Included In Earnings Pertaining To Level 3 Assets And Liabilities) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gains (losses) on insured derivatives			$ (1,506)	$ 1,307
Variable Interest Entity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(34)	22	(61)	(85)
Significant Unobservable Inputs (Level 3) [Member] | Total Gains (Losses) Included In Earnings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gains (losses) on insured derivatives	1,202	116	1,505	(1,307)
Net Realized Gains (Losses)	(446)	(220)	(543)	(608)
Net gains (losses) on financial instruments at fair value and foreign exchange	18	(38)	17	(78)
Significant Unobservable Inputs (Level 3) [Member] | Change In Unrealized Gains (Losses) For The Period Included In Earnings For Assets And Liabilities Still Held [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gains (losses) on insured derivatives	641	(897)	571	(2,128)
Net gains (losses) on financial instruments at fair value and foreign exchange	18	(41)	9	(79)
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity [Member] | Total Gains (Losses) Included In Earnings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(160)	63	(274)	(409)
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity [Member] | Change In Unrealized Gains (Losses) For The Period Included In Earnings For Assets And Liabilities Still Held [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ (148)	$ 114	$ (206)	$ (359)