Condensed Consolidated Statement 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, 2018	$ 1,471				$ 1,037	$ 1,043		$ (62)	$ (547)
Beginning balance, shares at Dec. 31, 2018			12,799,999	137,158,010					(12,056,688)
Net income (loss)	110
Cumulative effect adjustment from adoption of new accounting guidance at Dec. 31, 2018		$ 3					$ 3
Other comprehensive income (loss)	(13)							(13)
Issuance of common stock related to exercises of options and vesting of RSUs	$ 2				2
Issuance of common stock related to exercises of options and vesting of RSUs, shares				1,457,838
Repurchase of common stock, shares	0
Withholding taxes on net share settlements of equity awards	$ (28)				(28)
Stock-based compensation	103				103
Ending balance at Sep. 30, 2019	1,648				1,114	1,156		(75)	$ (547)
Ending balance, shares at Sep. 30, 2019			12,799,999	138,615,848					(12,056,688)
Beginning balance at Jun. 30, 2019	1,575				1,081	1,106		(65)	$ (547)
Beginning balance, shares at Jun. 30, 2019			12,799,999	138,525,158					(12,056,688)
Net income (loss)	50					50
Other comprehensive income (loss)	$ (10)							(10)
Issuance of common stock related to exercises of options and vesting of RSUs, shares				90,690
Repurchase of common stock, shares	0
Withholding taxes on net share settlements of equity awards	$ (1)				(1)
Stock-based compensation	34				34
Ending balance at Sep. 30, 2019	1,648				1,114	1,156		(75)	$ (547)
Ending balance, shares at Sep. 30, 2019			12,799,999	138,615,848					(12,056,688)
Beginning balance at Dec. 31, 2019	$ 1,161				1,150	681		(63)	$ (607)
Beginning balance, shares at Dec. 31, 2019	124,581,773		12,799,999	138,698,307					(14,116,534)
Net income (loss)	$ (217)					(217)
Cumulative effect adjustment from adoption of new accounting guidance at Dec. 31, 2019	681	$ (3)					$ (3)
Other comprehensive income (loss)	8							8
Issuance of common stock related to exercises of options and vesting of RSUs, shares				1,817,512
Repurchase of common stock	$ (115)								$ (115)
Repurchase of common stock, shares	(4,707,450)								(4,707,450)
Withholding taxes on net share settlements of equity awards	$ (18)				(18)
Stock-based compensation	92				92
Ending balance at Sep. 30, 2020	$ 908				1,224	461		(55)	$ (722)
Ending balance, shares at Sep. 30, 2020	121,671,205		12,799,999	140,515,819					(18,844,614)
Other, shares									(20,630)
Beginning balance at Jun. 30, 2020	$ 912				1,193	509		(68)	$ (722)
Beginning balance, shares at Jun. 30, 2020			12,799,999	140,412,251					(18,844,614)
Net income (loss)	(48)					(48)
Other comprehensive income (loss)	$ 13							13
Issuance of common stock related to exercises of options and vesting of RSUs, shares				103,568
Repurchase of common stock, shares	0
Withholding taxes on net share settlements of equity awards	$ (1)				(1)
Stock-based compensation	32				32
Ending balance at Sep. 30, 2020	$ 908				$ 1,224	$ 461		$ (55)	$ (722)
Ending balance, shares at Sep. 30, 2020	121,671,205		12,799,999	140,515,819					(18,844,614)