The Company and Summary of Significant Accounting Policies (Details) shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2021 USD ($) shares	Jun. 30, 2020 USD ($) segment	Jul. 20, 2020 USD ($)	Dec. 31, 2019 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments | segment		2
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for doubtful accounts		$ 140		$ 100
Increase in allowance for doubtful accounts receivable		40
Allowance for doubtful accounts receivable, write-offs		$ 61
Subsequent Event | Disposed by Sale | Classifieds
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amount of consideration to be received, subject to adjustments			$ 9,200
Forecast | Disposed by Sale | Classifieds
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from sale of business	$ 2,500
Number of shares to be received from the sale | shares	540
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, number of days outstanding		0 days
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, number of days outstanding		180 days