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)
Beginning balance (in shares) at Dec. 31, 2017			73,706
Beginning balance at Dec. 31, 2017		$ 1,661,914	$ 7	$ 804,731	$ 859,114	$ (1,938)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment to beginning balance		3,574			3,574
Net income (loss)		(10,731)			(10,731)
Other comprehensive income (loss), net of tax		(2,613)				(2,613)
Stock-based compensation		43,329		43,329
Issuance of common stock in connection with employee equity incentive plans (in shares)			1,103
Issuance of common stock in connection with employee equity incentive plans		28,810	$ 1	28,809
Tax withholding paid for net share settlement of equity awards (in shares)			(18)
Tax withholding paid for net share settlement of equity awards		(4,463)		(4,463)
Vesting of early-exercised stock options		153		153
Ending balance (in shares) at Jun. 30, 2018			74,791
Ending balance at Jun. 30, 2018		1,719,973	$ 8	872,559	851,957	(4,551)
Beginning balance (in shares) at Mar. 31, 2018			74,338
Beginning balance at Mar. 31, 2018		1,845,039	$ 8	841,431	1,007,226	(3,626)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment to beginning balance		0			0
Net income (loss)		(155,269)			(155,269)
Other comprehensive income (loss), net of tax		(925)				(925)
Stock-based compensation		22,478		22,478
Issuance of common stock in connection with employee equity incentive plans (in shares)			465
Issuance of common stock in connection with employee equity incentive plans		11,510	$ 0	11,510
Tax withholding paid for net share settlement of equity awards (in shares)			(12)
Tax withholding paid for net share settlement of equity awards		(2,927)		(2,927)
Vesting of early-exercised stock options		67		67
Ending balance (in shares) at Jun. 30, 2018			74,791
Ending balance at Jun. 30, 2018		1,719,973	$ 8	872,559	851,957	(4,551)
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment to beginning balance	[1]	3,702			3,702
Net income (loss)		390,280			390,280
Other comprehensive income (loss), 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)		(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]
Cumulative-effect adjustment to beginning balance	[1]	0			0
Net income (loss)		189,251			189,251
Other comprehensive income (loss), 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)		(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

[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. See Note 1 of the accompanying notes for further details.