Acquisitions and Discontinued Operations - Components of Income (Loss) from Discontinued Operations, Net of Taxes (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noninterest income	$ 459	$ 518	$ 1,313	$ 1,417
Noninterest expense	716	712	2,108	2,084
Income taxes	59	51	201	178
Income (loss) from discontinued operations, net of taxes	37	3	45	16
Segment, Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noninterest income	61	5	84	43
Noninterest expense	23	31	80	103
Income (loss) before income taxes	58	4	74	25
Income taxes	21	1	29	9
Income (loss) from discontinued operations, net of taxes	37	3	45	16
Segment, Discontinued Operations [Member] | Victory Capital Management [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noninterest income	155	26	212	84
Noninterest expense	16	22	59	67
Income (loss) before income taxes	139	4	153	17
Income taxes	52	1	57	6
Income (loss) from discontinued operations, net of taxes	87	3	96	11
Segment, Discontinued Operations [Member] | Austin Capital Management [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noninterest expense	1		1	9
Income (loss) before income taxes	(1)		(1)	(9)
Income taxes	(1)		1	(3)
Income (loss) from discontinued operations, net of taxes			$ (2)	$ (6)