Fair Values (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Investment securities:
Equity securities	$ 189,000,000	$ 296,000,000
Debt securities and other	5,073,000,000	5,318,000,000
Derivative assets	1,028,000,000	942,000,000
Total assets	6,290,000,000	6,556,000,000
Level 1 [Member]
Investment securities:
Equity securities	189,000,000	296,000,000
Debt securities and other	285,000,000	338,000,000
Derivative assets	0	0
Total assets	474,000,000	634,000,000
Level 2 [Member]
Investment securities:
Equity securities	0	0
Debt securities and other	4,788,000,000	4,980,000,000
Derivative assets	1,028,000,000	942,000,000
Total assets	5,816,000,000	5,922,000,000
Level 3 [Member]
Investment securities:
Total assets	$ 0	$ 0