Investment Securities (Contractual maturities) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Amortized cost
Within one year	$ 1,969
After one year through five years	3,681
After five years through ten years	5,241
After ten years	18,463
Estimated fair value
Within one year	1,981
After one year through five years	4,020
After five years through ten years	5,592
After ten years	$ 21,880