Regulation and Capital Adequacy - Consolidated Regulatory Capital Ratios (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Regulation And Capital Adequacy [Abstract]
Goodwill	$ 3,664	$ 3,666
Identifiable intangible assets deducted from CET1 during transitional period	322	257
Identifiable Intangible Assets	$ 403	$ 429
Increased deductions due to transitional provisions, percentage	80.00%	60.00%
Deferred tax liabilities associated with goodwill and identifiable intangible assets	$ 1,060	$ 1,050
Subordinated debt maturity period	5 years