Acquisitions and Discontinued Operations - Components of Income (Loss) from Discontinued Operations, Net of Taxes (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income	$ 563	$ 583
Noninterest income	435	425
Noninterest expense	662	681
Income taxes	92	70
Income (loss) from discontinued operations, net of taxes	4	3
Segment, Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income	24	28
Noninterest income	(4)	13
Noninterest expense	10	28
Income (loss) before income taxes	6	7
Income taxes	2	4
Income (loss) from discontinued operations, net of taxes	4	3
Segment, Discontinued Operations [Member] | Victory Capital Management [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest income	1
Noninterest income	10	29
Noninterest expense		21
Income (loss) before income taxes	11	8
Income taxes	4	3
Income (loss) from discontinued operations, net of taxes	7	5
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	4
Income (loss) before income taxes	(4)
Income taxes	(2)	2
Income (loss) from discontinued operations, net of taxes	$ (2)	$ (2)