Legal & Regulatory Proceedings - Additional Information (Details)	3 Months Ended				12 Months Ended
	Jun. 30, 2019 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2013 USD ($)
Loss Contingencies [Line Items]
Amount in excess of amounts reserved	$ 28,000,000
Number Of Putative Class Actions Filed						4
Damages sought	$ 280,000,000	$ 40,000,000	$ 800,000,000
Federal Lawsuits
Loss Contingencies [Line Items]
Number of merchants requesting exclusion				500
Class Action Settlement
Loss Contingencies [Line Items]
Number of merchants requesting exclusion				8,000
Escrow Deposit				$ 46,000,000
Litigation Settlement Amount Awarded To Other Party					$ 6,240,000,000
Escrow Funds Returned Defendants					700,000,000
Litigation Settlement Amount Awarded To Other Party, Escrow					5,300,000,000
Litigation Settlement Amount Awarded To Other Party, Additional					$ 900,000,000