Net Income Per Share - Potentially Dilutive Securities Excluded from the Computation of Diluted Net Income Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net income per unit (in shares)	5,762	5,040	7,352
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net income per unit (in shares)	28	0	2,228
Shares of Class B and Class C common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net income per unit (in shares)	0	0	191,426