Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment Revision of Prior Period, Adjustment	Class B Common Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment Revision of Prior Period, Adjustment	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2019	$ 1,161				$ 1,150	$ 681		$ (63)	$ (607)
Beginning balance, shares at Dec. 31, 2019			12,799,999	138,698,307					(14,116,534)
Net income (loss)	(169)					(169)
Cumulative effect adjustment from adoption of new accounting guidance at Dec. 31, 2019		$ (3)					$ (3)
Other comprehensive income (loss)	(5)							(5)
Issuance of common stock related to exercises of options and vesting of RSUs, shares				1,713,944
Repurchase of common stock (Note 10)	$ (115)								$ (115)
Repurchase of common stock, shares	(4,707,450)								(4,707,450)
Withholding taxes on net share settlements of equity awards	$ (17)				(17)
Stock-based compensation	60				60
Other, shares									(20,630)
Ending balance at Jun. 30, 2020	912				1,193	509		(68)	$ (722)
Ending balance, shares at Jun. 30, 2020			12,799,999	140,412,251					(18,844,614)
Beginning balance at Mar. 31, 2020	1,027				1,167	662		(80)	$ (722)
Beginning balance, shares at Mar. 31, 2020			12,799,999	140,109,681					(18,823,984)
Net income (loss)	(153)					(153)
Other comprehensive income (loss)	$ 12							12
Issuance of common stock related to exercises of options and vesting of RSUs, shares				302,570
Repurchase of common stock, shares	0
Withholding taxes on net share settlements of equity awards	$ (3)				(3)
Stock-based compensation	29				29
Other, shares									(20,630)
Ending balance at Jun. 30, 2020	912				1,193	509		(68)	$ (722)
Ending balance, shares at Jun. 30, 2020			12,799,999	140,412,251					(18,844,614)
Beginning balance at Dec. 31, 2020	$ 886				1,253	389		(34)	$ (722)
Beginning balance, shares at Dec. 31, 2020	121,930,607		12,799,999	140,775,221					(18,844,614)
Net income (loss)	$ (120)					(120)
Cumulative effect adjustment from adoption of new accounting guidance at Dec. 31, 2020	389
Other comprehensive income (loss)	(9)							(9)
Issuance of common stock related to exercises of options and vesting of RSUs	8				8
Issuance of common stock related to exercises of options and vesting of RSUs, shares				2,642,786
Purchase of capped calls, net of tax of $9 million (Note 6)	$ (26)				(26)
Repurchase of common stock, shares	0
Withholding taxes on net share settlements of equity awards	$ (29)				(29)
Stock-based compensation	69				69
Ending balance at Jun. 30, 2021	$ 779				1,275	269		(43)	$ (722)
Ending balance, shares at Jun. 30, 2021	124,573,393		12,799,999	143,418,007					(18,844,614)
Beginning balance at Mar. 31, 2021	$ 785				1,244	309		(46)	$ (722)
Beginning balance, shares at Mar. 31, 2021			12,799,999	142,914,851					(18,844,614)
Net income (loss)	(40)					(40)
Other comprehensive income (loss)	3							3
Issuance of common stock related to exercises of options and vesting of RSUs	$ 1				1
Issuance of common stock related to exercises of options and vesting of RSUs, shares				503,156
Repurchase of common stock, shares	0
Withholding taxes on net share settlements of equity awards	$ (6)				(6)
Stock-based compensation	36				36
Ending balance at Jun. 30, 2021	$ 779				$ 1,275	$ 269		$ (43)	$ (722)
Ending balance, shares at Jun. 30, 2021	124,573,393		12,799,999	143,418,007					(18,844,614)