Net Income (Loss) Per Share - Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Class A Common Stock and Class C Capital Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	46,097	26,288	53,654	26,508
Class A Common Stock and Class C Capital Stock | Weighted average | Option awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	518	18,900	27,333	19,394
Class A Common Stock and Class C Capital Stock | Weighted average | Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	62	6,964	8,367	6,690
Class A Common Stock | December 15, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	314	424	374	424
Class C Capital Stock | Convertible Notes Maturing in 2021, 2023, 2024, 2025 and 2026
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	45,203	0	17,580	0