Investment Securities (Contractual maturities) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Amortized Cost
Within one year	$ 1,935
After one year through five years	3,680
After five years through ten years	5,241
After ten years	18,463
Estimated Fair Value
Within one year	1,942
After one year through five years	4,018
After five years through ten years	5,592
After ten years	$ 21,880