Litigation (Details)	1 Months Ended				8 Months Ended	12 Months Ended				36 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Nov. 30, 2017 USD ($)	Jan. 31, 2017	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2012 USD ($) action	Dec. 31, 2013 USD ($)
Loss Contingencies [Line Items]
Legal expense/(benefit)						$ 239,000,000	$ 72,000,000	$ (35,000,000)
Threatened or Pending Litigation | Minimum
Loss Contingencies [Line Items]
Loss contingency range of possible loss	$ 0				$ 0	0
Threatened or Pending Litigation | Maximum
Loss Contingencies [Line Items]
Loss contingency range of possible loss	1,300,000,000				1,300,000,000	$ 1,300,000,000
Federal Republic of Nigeria Litigation | Federal Government of Nigeria and Two Major International Oil Companies
Loss Contingencies [Line Items]
Amount paid out of monies in account following settlement of dispute										$ 1,100,000,000
Federal Republic of Nigeria Litigation | Federal Republic of Nigeria
Loss Contingencies [Line Items]
Amount of claim			$ 875,000,000
Foreign Exchange Investigations and Litigation
Loss Contingencies [Line Items]
Loss contingency, exemption of disqualification period				5 years
Loss contingency disqualification period				10 years
Payments for fines in connection with legal settlement					$ 265,000,000
Interchange Litigation
Loss Contingencies [Line Items]
Number of separate actions | action									2
Interchange Litigation | The Defendants
Loss Contingencies [Line Items]
Payments for fines in connection with legal settlement	$ 700,000,000
Settlement amount		$ 900,000,000							$ 5,300,000,000