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)			558
Common stock issued under stock plans, net of withholdings and related tax effects	(12,038)		$ 1	(12,039)
Stock-based compensation	23,242			23,242
Repurchase of class A common stock (in shares)			(1,666)
Repurchases of Class A common stock	(100,000)		$ (2)	(99,998)
Net income	98,735				98,735
Other comprehensive income	2,162						2,162
Ending balance (in shares) at Jun. 30, 2019			51,809
Ending balance at Jun. 30, 2019	921,913		$ 52	291,958	627,878		2,025
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 Mar. 31, 2019			53,148
Beginning balance at Mar. 31, 2019	$ 978,715		$ 53	384,447	593,186		1,029
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans, net of withholdings and related tax effects (in shares)			327
Common stock issued under stock plans, net of withholdings and related tax effects	(917)		$ 1	(918)
Stock-based compensation	8,427			8,427
Repurchase of class A common stock (in shares)			(1,666)
Repurchases of Class A common stock	(100,000)		$ (2)	(99,998)
Net income	34,692				34,692
Other comprehensive income	996						996
Ending balance (in shares) at Jun. 30, 2019			51,809
Ending balance at Jun. 30, 2019	921,913		$ 52	291,958	627,878		2,025
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)			515
Common stock issued under stock plans, net of withholdings and related tax effects	1,873			1,873
Stock-based compensation	24,987			24,987
Walmart restricted shares (in shares)			975
Walmart restricted shares	0		$ 1	(1)
Net income	50,139				50,139
Other comprehensive income	151						151
Ending balance (in shares) at Jun. 30, 2020			53,297
Ending balance at Jun. 30, 2020	$ 1,004,225		$ 53	323,083	678,898		2,191
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Beginning balance (in shares) at Mar. 31, 2020			52,854
Beginning balance at Mar. 31, 2020	$ 988,005		$ 53	306,151	675,604		6,197
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans, net of withholdings and related tax effects (in shares)			443
Common stock issued under stock plans, net of withholdings and related tax effects	3,330			3,330
Stock-based compensation	13,602			13,602
Net income	3,294				3,294
Other comprehensive income	(4,006)						(4,006)
Ending balance (in shares) at Jun. 30, 2020			53,297
Ending balance at Jun. 30, 2020	$ 1,004,225		$ 53	$ 323,083	$ 678,898		$ 2,191