Acquisitions and Discontinued Operations - Components of Income (Loss) from Discontinued Operations, Net of Taxes for Education Lending Business (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income	$ 581	$ 538	$ 1,164	$ 1,091
Provision for loan and lease losses			82	62
Net interest income (expense) after provision for loan and lease losses	553	517	1,081	1,028
Noninterest income	(429)	(457)	(854)	(899)
Noninterest expense	711	693	1,392	1,372
Income taxes	72	54	142	127
Income (loss) from discontinued operations, net of taxes	5	14	8	13
Segment, Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income	26	30	54	61
Provision for loan and lease losses	(2)	2	4	6
Net interest income (expense) after provision for loan and lease losses	28	28	50	55
Noninterest income	(10)	(26)	(23)	(38)
Noninterest expense	29	31	57	72
Income (loss) before income taxes	9	23	16	21
Income taxes	4	9	8	8
Income (loss) from discontinued operations, net of taxes	5	14	8	13
Education Lending [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) before income taxes	3	17	2	17
Income taxes	2	6	1	6
Income (loss) from discontinued operations, net of taxes	1	11	1	11
Education Lending [Member] | Segment, Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income	26	30	54	61
Provision for loan and lease losses	(2)	2	4	6
Net interest income (expense) after provision for loan and lease losses	28	28	50	55
Noninterest income	(18)	(2)	(34)	(20)
Noninterest expense	$ 7	$ 9	$ 14	$ 18