Guarantees and Contingent Liabilities - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Guarantees And Contingent Liabilities (Textual) [Abstract]
Liability related to remaining Visa Litigation, carrying amount	$ 19	$ 19
Asset Sales [Member]
Guarantees And Contingent Liabilities (Textual) [Abstract]
Representation and warranty reserve	11	11	$ 13
Unresolved representation and warranty claims from GSEs	15	15	$ 9
Merchant Processing [Member]
Guarantees And Contingent Liabilities (Textual) [Abstract]
Value of airline tickets purchased to deliver at future date through card transactions	10,700	10,700
Company held collateral in escrow deposits, letters of credit and indemnities from financial institutions and liens on various assets	615	615
Liability primarily related to airline processing arrangements	$ 56	$ 56
Visa Class B Shares [Member]
Guarantees And Contingent Liabilities (Textual) [Abstract]
Number of shares sold	0.2	0.5
Remaining shares held by the Company	2.2	2.2