Derivative Instruments - Asset and Liability Management Derivative Positions of Company (Parenthetical) (Detail) - Asset and Liability Management Positions [Member] - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Value, Assets	$ 47,709	$ 25,635
Notional Value, Liabilities	65,657	26,756
Fair Value, Liabilities	213	123
Swap [Member] | Visa Class B Shares [Member]
Derivative [Line Items]
Notional Value, Liabilities	1,700	1,500
Fair Value, Liabilities	$ 52	$ 84
Derivative Liability Average Remaining Maturity Period	9 months	1 year 6 months
Underwriting Purchase and Sale Commitments [Member]
Derivative [Line Items]
Notional Value, Assets	$ 675	$ 1
Notional Value, Liabilities	$ 675	$ 1