UNAUDITED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Amortized cost of available-for-sale debt securities, current	$ 500	$ 500
Accounts receivable, allowance for credit loss	92	166
Prepaid expenses, allowance for credit loss, current	30	22
Amortized cost of available-for-sale debt securities, noncurrent	225	225
Prepaid expenses, allowance for credit loss, noncurrent	$ 24	$ 33
Common stock, par value (in dollars per share)	$ 0.008	$ 0.008
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	63,574,902	63,406,451
Treasury stock, shares (in shares)	22,515,119	22,446,897