Acquisitions and Discontinued Operations - Combined Results of Discontinued Operations (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
Provision (credit) for loan and lease losses	6	54
Net interest income (expense) after provision for loan and lease losses	557	528
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
Provision (credit) for loan and lease losses	4	6
Net interest income (expense) after provision for loan and lease losses	20	22
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