Restrictions (Restrictions on Cash, Dividends and Other Capital Actions- Additional Information) (Detail) - USD ($)	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2015	Jun. 30, 2014	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2011
Restricted Cash and Cash Equivalents Items
Banking Subsidiary Reserve Requirement	$ 1,500,000,000									$ 1,500,000,000	$ 1,500,000,000
Dividend Received From Nonbank Companies And Related Subsidiaries										$ 1,900,000,000	2,300,000,000
BHC stress test threshold													$ 50,000,000,000
Common stock dividends restrictions										The increase in the quarterly common stock dividend to $0.22 from $0.18 beginning in the fourth quarter of 2018 and to $0.24 beginning in the second quarter of 2019
Stock Repurchase Authorization Amount	1,810,000,000	$ 1,651,000,000								$ 1,810,000,000	1,161,000,000
Increase to quarterly common stock dividend	0.22
Gain on sale of Worldpay, Inc. shares		$ 205,000,000	$ 414,000,000							205,000,000	1,037,000,000	$ 0
Worldpay Holding, LLC
Restricted Cash and Cash Equivalents Items
Gain on sale of Worldpay, Inc. shares				$ 331,000,000	$ 125,000,000	$ 85,000,000	$ 242,000,000	$ 157,000,000	$ 115,000,000
Yearly Average
Restricted Cash and Cash Equivalents Items
Banking Subsidiary Reserve Requirement	1,500,000,000									1,500,000,000	$ 1,400,000,000
CCAR authorization
Restricted Cash and Cash Equivalents Items
Stock Repurchase Authorization Amount	81,000,000									81,000,000
CCAR authorization | Repurchases related to previously-recognized TRA transaction after-tax gains
Restricted Cash and Cash Equivalents Items
Stock Repurchase Authorization Amount	$ 53,000,000									$ 53,000,000