CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Amortized cost of available-for-sale debt securities, current	$ 500	$ 998
Accounts receivable, net, allowance for expected credit losses, current	166	49
Prepaid expenses, net, allowance for expected credit losses, current	22	6
Amortized cost of available-for-sale debt securities, noncurrent	225	2,192
Prepaid expenses, net, allowance for expected credit losses, noncurrent	$ 33	$ 0
Common stock, par value (in dollars per share)	$ 0.008	$ 0.008
Common stock, authorized shares (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	63,406,451	63,179,471
Treasury stock, shares (in shares)	22,446,897	21,762,070