Cash Equivalents and Investments (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Fair Value	$ 50	$ 3
Cash and cash equivalents	2,492	1,832
Short-term investments	96	98
Certificates of deposit and money market deposit accounts
Cash and Cash Equivalents [Line Items]
Cost	1,387	971
Gains/(Losses)	0	0
Fair Value	1,387	971
Cash and cash equivalents	1,284	866
Short-term investments	96	95
Other assets	7	10
Mutual funds
Cash and Cash Equivalents [Line Items]
Cost	47	3
Gains/(Losses)	3	0
Fair Value	50	3
Cash and cash equivalents	0	0
Short-term investments	0	3
Other assets	$ 50	$ 0