Loans and Interest Receivable - Delinquency Status of the Principal Amount of Loans and Interest Receivables (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Consumer Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, current	$ 1,327	$ 1,279
Loans, advances, and interest receivable	$ 1,377	$ 1,322
Loans, advances, and interest receivable, current, percentage	96.40%	96.70%
Loans, advances, and interest receivable, percentage	100.00%	100.00%
Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, current	$ 2,682	$ 2,523
Loans, advances, and interest receivable, past due		293
Loans, advances, and interest receivable	$ 2,995	$ 2,816
Loans, advances, and interest receivable, current, percentage	89.60%	89.60%
Loans, advances, and interest receivable, past due, percentage		10.40%
Loans, advances, and interest receivable, percentage	100.00%	100.00%
30 - 59 Days Past Due | Consumer Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	$ 18	$ 15
Loans, advances, and interest receivable, past due, percentage	1.30%	1.10%
30 - 59 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	$ 120	$ 115
Loans, advances, and interest receivable, past due, percentage	4.00%	4.10%
60 - 89 Days Past Due | Consumer Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	$ 11	$ 9
Loans, advances, and interest receivable, past due, percentage	0.80%	0.70%
60 - 89 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	$ 67	$ 61
Loans, advances, and interest receivable, past due, percentage	2.20%	2.10%
90 - 180 Days Past Due | Consumer Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	$ 21	$ 19
Loans, advances, and interest receivable, past due, percentage	1.50%	1.50%
90 - 180 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	$ 109	$ 100
Loans, advances, and interest receivable, past due, percentage	3.60%	3.60%
More Than 180 Days | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	$ 17	$ 17
Loans, advances, and interest receivable, past due, percentage	0.60%	0.60%
Financial Asset, 2020 Origination | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, current	$ 1,388
Loans, advances, and interest receivable	1,408
Financial Asset, 2020 Origination | 30 - 59 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	17
Financial Asset, 2020 Origination | 60 - 89 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	3
Financial Asset, 2020 Origination | 90 - 180 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	0
Financial Asset, 2020 Origination | More Than 180 Days | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	0
Financial Asset, 2019 Origination | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, current	1,266
Loans, advances, and interest receivable	1,513
Financial Asset, 2019 Origination | 30 - 59 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	90
Financial Asset, 2019 Origination | 60 - 89 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	56
Financial Asset, 2019 Origination | 90 - 180 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	94
Financial Asset, 2019 Origination | More Than 180 Days | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	7
Financial Asset, 2018 Origination | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, current	28
Loans, advances, and interest receivable	73
Financial Asset, 2018 Origination | 30 - 59 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	13
Financial Asset, 2018 Origination | 60 - 89 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	8
Financial Asset, 2018 Origination | 90 - 180 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	15
Financial Asset, 2018 Origination | More Than 180 Days | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	9
Financial Asset, 2017 Origination | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, current	0
Loans, advances, and interest receivable	1
Financial Asset, 2017 Origination | 30 - 59 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	0
Financial Asset, 2017 Origination | 60 - 89 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	0
Financial Asset, 2017 Origination | 90 - 180 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	0
Financial Asset, 2017 Origination | More Than 180 Days | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	1
Financial Asset, 2016 Origination | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, current	0
Loans, advances, and interest receivable	0
Financial Asset, 2016 Origination | 30 - 59 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	0
Financial Asset, 2016 Origination | 60 - 89 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	0
Financial Asset, 2016 Origination | 90 - 180 Days Past Due | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	0
Financial Asset, 2016 Origination | More Than 180 Days | Merchant Receivables
Financing Receivable, Past Due [Line Items]
Loans, advances, and interest receivable, past due	$ 0