Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Cumulative Effect, Period of Adoption, Adjustment	[1]	Cumulative Effect, Period of Adoption, Adjustment Retained Earnings	[1]
Beginning balance (in shares) at Dec. 31, 2018		75,668
Beginning balance at Dec. 31, 2018	$ 2,143,389	$ 8	$ 956,572	$ 1,190,803	$ (3,994)	$ 3,702		$ 3,702
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	390,280			390,280
Other comprehensive income, net of tax	6,029				6,029
Stock-based compensation	48,588		48,588
Issuance of common stock in connection with employee equity incentive plans (in shares)		1,312
Issuance of common stock in connection with employee equity incentive plans	38,104		38,104
Tax withholding paid for net share settlement of equity awards (in shares)		(18)
Tax withholding paid for net share settlement of equity awards	(4,662)		(4,662)
Vesting of early-exercised stock options	138		138
Repurchase of common stock (in shares)		(407)
Repurchase of common stock	(100,008)			(100,008)
Ending balance (in shares) at Jun. 30, 2019		76,555
Ending balance at Jun. 30, 2019	2,525,560	$ 8	1,038,740	1,484,777	2,035
Beginning balance (in shares) at Mar. 31, 2019		76,453
Beginning balance at Mar. 31, 2019	2,400,367	$ 8	1,005,405	1,395,534	(580)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	189,251			189,251
Other comprehensive income, net of tax	2,615				2,615
Stock-based compensation	24,297		24,297
Issuance of common stock in connection with employee equity incentive plans (in shares)		521
Issuance of common stock in connection with employee equity incentive plans	11,781		11,781
Tax withholding paid for net share settlement of equity awards (in shares)		(12)
Tax withholding paid for net share settlement of equity awards	(2,812)		(2,812)
Vesting of early-exercised stock options	69		69
Repurchase of common stock (in shares)		(407)
Repurchase of common stock	(100,008)			(100,008)
Ending balance (in shares) at Jun. 30, 2019		76,555
Ending balance at Jun. 30, 2019	2,525,560	$ 8	1,038,740	1,484,777	2,035
Beginning balance (in shares) at Dec. 31, 2019		76,389
Beginning balance at Dec. 31, 2019	2,894,686	$ 8	1,106,305	1,788,230	143
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	283,224			283,224
Other comprehensive income, net of tax	7,680				7,680
Stock-based compensation	60,478		60,478
Issuance of common stock in connection with employee equity incentive plans (in shares)		801
Issuance of common stock in connection with employee equity incentive plans	22,228		22,228
Tax withholding paid for net share settlement of equity awards (in shares)		(17)
Tax withholding paid for net share settlement of equity awards	(4,000)		(4,000)
Vesting of early-exercised stock options	82		82
Repurchase of common stock (in shares)		(1,209)
Repurchase of common stock	(227,895)	$ (227,895)		(227,895)
Ending balance (in shares) at Jun. 30, 2020		75,964
Ending balance at Jun. 30, 2020	3,036,483	$ 8	1,185,093	1,843,559	7,823
Beginning balance (in shares) at Mar. 31, 2020		75,655
Beginning balance at Mar. 31, 2020	2,848,826	$ 8	1,149,224	1,698,766	828
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	144,793			144,793
Other comprehensive income, net of tax	6,995				6,995
Stock-based compensation	32,922		32,922
Issuance of common stock in connection with employee equity incentive plans (in shares)		319
Issuance of common stock in connection with employee equity incentive plans	5,146		5,146
Tax withholding paid for net share settlement of equity awards (in shares)		(10)
Tax withholding paid for net share settlement of equity awards	(2,260)		(2,260)
Vesting of early-exercised stock options	61		61
Repurchase of common stock (in shares)		0
Repurchase of common stock	0
Ending balance (in shares) at Jun. 30, 2020		75,964
Ending balance at Jun. 30, 2020	$ 3,036,483	$ 8	$ 1,185,093	$ 1,843,559	$ 7,823

[1] On January 1, 2019, we adopted Accounting Standard Codification Topic 842 - Leases ("ASC 842"), which resulted in a cumulative-effect adjustment to the beginning balance of Retained Earnings for 2019.