Fair Value Measurement of Assets and Liabilities - Summary of Investments Under the Fair Value Option (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	$ 16,338		$ 16,338		$ 12,013
Fair Value Option, Investments | Funds receivable and customer accounts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	2,001		2,001		1,690
Net gains (losses) from fair value changes	17	$ 27	(3)	$ (2)
Fair Value Option, Investments | Short term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	0		0		$ 246
Net gains (losses) from fair value changes	$ (6)	$ (4)	$ (24)	$ (4)