Stockholders’ Equity and Stock-Based Compensation - Option Activities (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Number of Shares Underlying Outstanding Options
Outstanding, beginning balance (in shares)	3,430
Options granted (in shares)	0
Options exercised (in shares)	(947)
Options canceled (in shares)	(22)
Outstanding, ending balance (in shares)	2,461	3,430
Vested and exercisable (in shares)	1,814
Weighted- Average Exercise Price per Share
Outstanding, beginning balance (in dollars per share)	$ 45.17
Options granted (in dollars per share)	0
Options exercised (in dollars per share)	36.81
Options canceled (in dollars per share)	38.54
Outstanding, ending balance (in dollars per share)	48.44	$ 45.17
Vested and exercisable (in dollars per share)	$ 36.95
Weighted- Average Remaining Contractual Term (Years) and Aggregate Intrinsic Value of Stock Options
Weighted-average remaining contractual term of stock options outstanding	3 years	3 years 7 months 6 days
Weighted-average remaining contractual term of stock options vested and exercisable	2 years 7 months 6 days
Aggregate intrinsic value of stock options outstanding	$ 726,600	$ 841,659
Aggregate intrinsic value of stock options outstanding, vested and exercisable	$ 556,227