The Company and Summary of Significant Accounting Policies (Details) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2021 USD ($) shares	Sep. 30, 2020 USD ($) segment	Jul. 17, 2020 USD ($)	Dec. 31, 2019 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments | segment		1
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for doubtful accounts		$ 105		$ 82
Increase in allowance for doubtful accounts receivable		23
Allowance for doubtful accounts receivable, write-offs		$ 80
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
Discontinued Operations, Held-for-sale | Classifieds
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amount of consideration to be received, subject to adjustments			$ 9,200
Discontinued Operations, Held-for-sale | Classifieds | Forecast
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