CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Class A Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income
Beginning balance (in shares) at Dec. 31, 2018			52,917
Beginning balance at Dec. 31, 2018	$ 909,812		$ 53	$ 380,753	$ 529,143		$ (137)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans, net of withholdings and related tax effects (in shares)			634
Common stock issued under stock plans, net of withholdings and related tax effects	(13,297)		$ 1	(13,298)
Stock-based compensation	30,136			30,136
Repurchase of class A common stock (in shares)			(2,072)
Repurchases of Class A common stock	(100,000)		$ (2)	(99,998)
Net income (loss)	98,204				98,204
Other comprehensive income	2,329						2,329
Ending balance (in shares) at Sep. 30, 2019			51,479
Ending balance at Sep. 30, 2019	927,184		$ 52	297,593	627,347		2,192
Beginning balance (in shares) at Dec. 31, 2018			52,917
Beginning balance at Dec. 31, 2018	909,812		$ 53	380,753	529,143		(137)
Ending balance (in shares) at Dec. 31, 2019			51,807
Ending balance at Dec. 31, 2019	$ 927,356	$ (281)	$ 52	296,224	629,040	$ (281)	2,040
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Beginning balance (in shares) at Jun. 30, 2019			51,809
Beginning balance at Jun. 30, 2019	$ 921,913		$ 52	291,958	627,878		2,025
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans, net of withholdings and related tax effects (in shares)			76
Common stock issued under stock plans, net of withholdings and related tax effects	(1,259)			(1,259)
Stock-based compensation	6,894			6,894
Repurchase of class A common stock (in shares)			(406)
Repurchases of Class A common stock	0
Net income (loss)	(531)				(531)
Other comprehensive income	167						167
Ending balance (in shares) at Sep. 30, 2019			51,479
Ending balance at Sep. 30, 2019	927,184		$ 52	297,593	627,347		2,192
Beginning balance (in shares) at Dec. 31, 2019			51,807
Beginning balance at Dec. 31, 2019	927,356	$ (281)	$ 52	296,224	629,040	$ (281)	2,040
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans, net of withholdings and related tax effects (in shares)			677
Common stock issued under stock plans, net of withholdings and related tax effects	(3,049)			(3,049)
Stock-based compensation	36,793			36,793
Walmart restricted shares (in shares)			975
Walmart restricted shares	0		$ 1	(1)
Net income (loss)	47,147				47,147
Other comprehensive income	907						907
Ending balance (in shares) at Sep. 30, 2020			53,459
Ending balance at Sep. 30, 2020	$ 1,008,873		$ 53	329,967	675,906		2,947
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Beginning balance (in shares) at Jun. 30, 2020			53,297
Beginning balance at Jun. 30, 2020	$ 1,004,225		$ 53	323,083	678,898		2,191
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans, net of withholdings and related tax effects (in shares)			162
Common stock issued under stock plans, net of withholdings and related tax effects	(4,922)			(4,922)
Stock-based compensation	11,806			11,806
Net income (loss)	(2,992)				(2,992)
Other comprehensive income	756						756
Ending balance (in shares) at Sep. 30, 2020			53,459
Ending balance at Sep. 30, 2020	$ 1,008,873		$ 53	$ 329,967	$ 675,906		$ 2,947