Asset Quality - Nonperforming Assets and Past Due Loans (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Disclosure Loans Classified As Nonperforming [Abstract]
Total nonperforming loans	$ 652	$ 674	$ 657
Nonperforming loans held for sale	14	25	38
OREO	18	22	28
Other nonperforming assets	9	14	28
Total nonperforming assets	693	735	751
Nonperforming assets from discontinued operations - education lending	19	20	18
Restructured loans included in nonperforming loans	195	249	163
Restructured loans with an allocated specific allowance	65	114	71
Specifically allocated allowance for restructured loans	30	33	34
Accruing loans past due 90 days or more	80	78	131
Accruing loans past due 30 through 89 days	$ 251	$ 424	$ 362