Regulatory Capital and Ratios (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Tier 1 Risk-Based Capital
Actual Amount	$ 5,431
Minimum Capital Requirement Amount	985
Minimum to be Well Capitalized Amount	1,477
Actual Ratio	22.10%
Minimum Capital Requirement Ratio	4.00%
Minimum to be Well Capitalized Ratio	6.00%
Total Risk-Based Capital
Actual Amount	5,479
Minimum Capital Requirement Amount	1,970
Minimum to be Well Capitalized Amount	2,462
Actual Ratio	22.30%
Minimum Capital Requirement Ratio	8.00%
Minimum to be Well Capitalized Ratio	10.00%
Tier 1 Leverage
Actual Amount	5,431
Minimum Capital Requirement Amount	2,876
Minimum to be Well Capitalized Amount	3,595
Actual Ratio	7.60%
Minimum Capital Requirement Ratio	4.00%
Minimum to be Well Capitalized Ratio	5.00%
Tangible Equity
Actual Amount	5,431
Minimum Capital Requirement Amount	$ 1,438
Actual Ratio	7.60%
Minimum Capital Requirement Ratio	2.00%