Restrictions (Restrictions on Cash, Dividends and Other Capital Actions- Additional Information) (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2011
Restricted Cash and Cash Equivalents Items
Banking Subsidiary Reserve Requirement	$ 1,600,000,000	$ 1,600,000,000	$ 1,900,000,000
Dividend Received From Nonbank Companies And Related Subsidiaries		1,900,000,000	1,000,000,000
BHC stress test threshold					$ 50,000,000,000
Shares acquired for treasury		661,000,000	850,000,000	$ 654,000,000
Increase to quarterly common stock dividend	0.14
Yearly Average
Restricted Cash and Cash Equivalents Items
Banking Subsidiary Reserve Requirement	1,600,000,000	1,600,000,000	$ 1,800,000,000
March 2, 2016 ASR
Restricted Cash and Cash Equivalents Items
Shares acquired for treasury		240,000,000
June 15, 2016 Open Market Share Repurchase
Restricted Cash and Cash Equivalents Items
Shares acquired for treasury		26,000,000
August 3, 2016 ASR
Restricted Cash and Cash Equivalents Items
Shares acquired for treasury		240,000,000
December 16, 2016 ASR
Restricted Cash and Cash Equivalents Items
Shares acquired for treasury		$ 155,000,000
CCAR authorization
Restricted Cash and Cash Equivalents Items
Common stock dividends restrictions		The potential increase in the quarterly common stock dividend to $0.14 in the fourth quarter of 2016
Stock Repurchase Authorization Amount	660,000,000	$ 660,000,000
CCAR authorization | Repurchases related to share issuances under employee benefit plans
Restricted Cash and Cash Equivalents Items
Stock Repurchase Authorization Amount	$ 84,000,000	$ 84,000,000