Regulatory Requirements (Regulatory Capital and Ratios) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014
Tier 1 Risk-Based Capital
Actual Amount	$ 7,450
Minimum Capital Requirement Amount	1,374
Minimum to be Well Capitalized Amount	2,061
Actual Ratio	21.70%
Minimum Capital Requirement Ratio	4.00%
Minimum to be Well Capitalized Ratio	6.00%
Total Risk-Based Capital
Actual Amount	7,491
Minimum Capital Requirement Amount	2,749
Minimum to be Well Capitalized Amount	3,436
Actual Ratio	21.80%
Minimum Capital Requirement Ratio	8.00%
Minimum to be Well Capitalized Ratio	10.00%
Tier 1 Leverage
Actual Amount	7,450
Minimum Capital Requirement Amount	4,212
Minimum to be Well Capitalized Amount	5,265
Actual Ratio	7.10%
Minimum Capital Requirement Ratio	4.00%
Minimum to be Well Capitalized Ratio	5.00%
Tangible Equity
Actual Amount	7,450
Minimum Capital Requirement Amount	$ 2,106
Actual Ratio	7.10%
Minimum Capital Requirement Ratio	2.00%