CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands	Total	Adjustment	Common Stock	Additional paid in capital	Accumulated other comprehensive loss	Retained earnings (Accumulated deficit)	Retained earnings (Accumulated deficit) Adjustment
Balance at beginning of period (shares) at Dec. 31, 2019			16,823
Balance at beginning of period at Dec. 31, 2019	$ 767,232,000	$ (5,167,000)	$ 17,000	$ 367,326,000	$ (216,000)	$ 400,105,000	$ (5,167,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock compensation plans, net (shares)			105
Issuance of common stock under employee stock compensation plans, net	(1,008,000)			(1,008,000)
Share-based compensation	5,653,000			5,653,000
Repurchase of common stock (shares)			(878)
Repurchase of common stock	(73,287,000)		$ (1,000)	(73,286,000)
Unrealized net gain (loss) on available-for-sale securities, net of deferred tax	(2,772,000)				(2,772,000)
Foreign currency translation adjustment	(1,879,000)				(1,879,000)
Reacquisition of equity due to 2023 debt extinguishment, net of tax	(2,745,000)			(2,745,000)
Net income (loss)	(24,131,000)					(24,131,000)
Balance at end of period (shares) at Mar. 31, 2020			16,050
Balance at end of period at Mar. 31, 2020	661,896,000		$ 16,000	295,940,000	(4,867,000)	370,807,000
Balance at beginning of period (shares) at Dec. 31, 2019			16,823
Balance at beginning of period at Dec. 31, 2019	767,232,000	$ (5,167,000)	$ 17,000	367,326,000	(216,000)	400,105,000	$ (5,167,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(8,746,000)
Balance at end of period (shares) at Sep. 30, 2020			16,091
Balance at end of period at Sep. 30, 2020	697,824,000		$ 16,000	313,057,000	(1,441,000)	386,192,000
Balance at beginning of period (shares) at Mar. 31, 2020			16,050
Balance at beginning of period at Mar. 31, 2020	661,896,000		$ 16,000	295,940,000	(4,867,000)	370,807,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock compensation plans, net (shares)			21
Issuance of common stock under employee stock compensation plans, net	1,128,000			1,128,000
Share-based compensation	7,359,000			7,359,000
Unrealized net gain (loss) on available-for-sale securities, net of deferred tax	2,742,000				2,742,000
Foreign currency translation adjustment	(185,000)				(185,000)
Adjustment on reacquisition of equity due to 2023 debt extinguishment, net of tax	(23,000)			(23,000)
Net income (loss)	22,086,000					22,086,000
Balance at end of period (shares) at Jun. 30, 2020			16,071
Balance at end of period at Jun. 30, 2020	695,003,000		$ 16,000	304,404,000	(2,310,000)	392,893,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock compensation plans, net (shares)			20
Issuance of common stock under employee stock compensation plans, net	910,000			910,000
Share-based compensation	7,740,000			7,740,000
Unrealized net gain (loss) on available-for-sale securities, net of deferred tax	(54,000)				(54,000)
Foreign currency translation adjustment	923,000				923,000
Other	3,000			3,000
Net income (loss)	(6,701,000)					(6,701,000)
Balance at end of period (shares) at Sep. 30, 2020			16,091
Balance at end of period at Sep. 30, 2020	697,824,000		$ 16,000	313,057,000	(1,441,000)	386,192,000
Balance at beginning of period (shares) at Dec. 31, 2020			16,080
Balance at beginning of period at Dec. 31, 2020	709,525,000		$ 16,000	318,358,000	(801,000)	391,952,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock compensation plans, net (shares)			572
Issuance of common stock under employee stock compensation plans, net	20,581,000		$ 1,000	20,580,000
Share-based compensation	8,405,000			8,405,000
Unrealized net gain (loss) on available-for-sale securities, net of deferred tax	(55,000)				(55,000)
Reacquisition of equity due to 2023 debt extinguishment, net of tax	(9,086,000)			(9,086,000)
Warrant and bond hedge unwind transactions	396,000			396,000
Tax effect for 2023 Notes transactions	(2,032,000)			(2,032,000)
Net income (loss)	18,106,000					18,106,000
Balance at end of period (shares) at Mar. 31, 2021			16,652
Balance at end of period at Mar. 31, 2021	745,840,000		$ 17,000	336,621,000	(856,000)	410,058,000
Balance at beginning of period (shares) at Dec. 31, 2020			16,080
Balance at beginning of period at Dec. 31, 2020	709,525,000		$ 16,000	318,358,000	(801,000)	391,952,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock	0
Net income (loss)	62,554,000
Balance at end of period (shares) at Sep. 30, 2021			16,707
Balance at end of period at Sep. 30, 2021	812,066,000		$ 17,000	358,418,000	(875,000)	454,506,000
Balance at beginning of period (shares) at Mar. 31, 2021			16,652
Balance at beginning of period at Mar. 31, 2021	745,840,000		$ 17,000	336,621,000	(856,000)	410,058,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock compensation plans, net (shares)			24
Issuance of common stock under employee stock compensation plans, net	1,103,000			1,103,000
Share-based compensation	10,216,000			10,216,000
Unrealized net gain (loss) on available-for-sale securities, net of deferred tax	(5,000)				(5,000)
Reacquisition of equity due to 2023 debt extinguishment, net of tax	(1,073,000)			(1,073,000)
Tax effect for 2023 Notes transactions	(289,000)			(289,000)
Net income (loss)	30,725,000					30,725,000
Balance at end of period (shares) at Jun. 30, 2021			16,676
Balance at end of period at Jun. 30, 2021	786,517,000		$ 17,000	346,578,000	(861,000)	440,783,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock compensation plans, net (shares)			31
Issuance of common stock under employee stock compensation plans, net	1,898,000			1,898,000
Share-based compensation	9,754,000			9,754,000
Unrealized net gain (loss) on available-for-sale securities, net of deferred tax	(14,000)				(14,000)
Reacquisition of equity due to 2023 debt extinguishment, net of tax	(32,000)			(32,000)
Warrant and bond hedge unwind transactions	96,000			96,000
Tax effect for 2023 Notes transactions	124,000			124,000	0
Net income (loss)	13,723,000					13,723,000
Balance at end of period (shares) at Sep. 30, 2021			16,707
Balance at end of period at Sep. 30, 2021	$ 812,066,000		$ 17,000	$ 358,418,000	$ (875,000)	$ 454,506,000