Investments - Narrative (Details) shares in Millions		3 Months Ended		6 Months Ended
	Jul. 14, 2021 USD ($) shares	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jul. 12, 2021	Jun. 24, 2021 USD ($)	Dec. 31, 2020 USD ($)
Investments [Abstract]
Investment securities in a continuous unrealized loss position for less then 12 months		$ 3,000,000,000.0		$ 3,000,000,000.0				$ 261,000,000
Estimated fair value for securities in continuous unrealized loss position for greater than 12 months		0		0				$ 0
Schedule of Equity Method Investments [Line Items]
Upward adjustments for observable price changes		41,000,000	$ 0	41,000,000	$ 0
Change in fair value of equity investment in Adevinta		422,000,000		$ 422,000,000	$ 0
Strategic Investment
Schedule of Equity Method Investments [Line Items]
Upward adjustments for observable price changes		$ 41,000,000
Adevinta
Schedule of Equity Method Investments [Line Items]
Ownership percentage							44.00%
Value of equity method investment at acquisition date							$ 10,800,000,000
Voting rights, conversion ratio							1
Adevinta | Maximum
Schedule of Equity Method Investments [Line Items]
Limitation on voting interest that can be held (as a percent)							33.00%
Adevinta | Subsequent Event
Schedule of Equity Method Investments [Line Items]
Discount rate on 10-day VWAP						7.00%
Discount rate on 30-day VWAP						5.00%
Adevinta | Subsequent Event | Permira
Schedule of Equity Method Investments [Line Items]
Number of shares in equity investment | shares	125
Total consideration in sale of equity investment	$ 2,250,000,000
Sale of equity investment, option period	30 days
Number of additional shares in option to purchase | shares	10
Additional consideration in option to purchase	$ 180,000,000