Acquisition, Divestiture, and Discontinued Operations - Combined Assets and Liabilities of Discontinued Operations (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and due from banks	$ 677	$ 607	$ 653	$ 617
Held-to-maturity securities	10,232	4,897
Portfolio loans at fair value	3	4
Loans net of deferred income	86,038	59,876	$ 57,381
Total assets	1,585	1,846
Unearned income on loans	826	646
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and due from banks	15	15
Held-to-maturity securities	1	1
Portfolio loans at fair value	3	4
Loans net of deferred income	1,562	1,824
Less: Allowance for loan and lease losses	24	28
Net loans	1,541	1,800
Accrued income and other assets	28	30
Total assets	1,585	1,846
Unearned income on loans	$ 1	$ 1