Fair Values (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Investment securities:
Equity securities	$ 281,000,000	$ 360,000,000
Debt securities and other	5,779,000,000	6,787,000,000
Derivatives	1,089,000,000	1,516,000,000
Total assets	7,149,000,000	8,663,000,000
Level 1 [Member]
Investment securities:
Equity securities	281,000,000	360,000,000
Debt securities and other	339,000,000	340,000,000
Derivatives	0	0
Total assets	620,000,000	700,000,000
Level 2 [Member]
Investment securities:
Equity securities	0	0
Debt securities and other	5,440,000,000	6,447,000,000
Derivatives	1,089,000,000	1,516,000,000
Total assets	6,529,000,000	7,963,000,000
Level 3 [Member]
Investment securities:
Total assets	$ 0	$ 0