Cash and Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2020

Cash And Marketable Securities [Abstract]

Schedule Of Amortized Cost, Fair Value And Gross Unrealized Gains And Losses Of The Company's Short- And Long-Term Investments In Debt And Equity Securities

			Gross Realized		Gross Realized
	Amortized		and Unrealized		and Unrealized		Fair
(In millions)	Cost		Gains		Losses		Value
March 31, 2020:
Debt securities	$	4	$	—	$	—	$	4
Equity securities		8		—		—		8
Total securities	$	12	$	—	$	—	$	12
December 31, 2019:
Debt securities	$	4	$	—	$	—	$	4
Equity securities		9		—		—		9
Total securities	$	13	$	—	$	—	$	13