Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2018
Numerator:
Net income (loss) attributable to common stockholders	$ 4,357	$ (6,240)	$ (46,409)	$ (3,545)
Denominator:
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, basic (in shares)	66,265	63,966	65,895	62,842
Effect of dilutive securities:
Convertible senior notes (in shares)	1,289	0	0	0
Employee stock awards (in shares)	2,220	0	0	0
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, diluted (in shares)	69,774	63,966	65,895	62,842
Net income (loss) per share attributable to common stockholders, basic (in dollars per share)	$ 0.07	$ (0.10)	$ (0.70)	$ (0.06)
Net income (loss) per share attributable to common stockholders, diluted (in dollars per share)	$ 0.06	$ (0.10)	$ (0.70)	$ (0.06)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from calculation of earnings per share (in shares)	4,538	10,198	10,180	10,110
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from calculation of earnings per share (in shares)	313	4,483	4,043	4,744
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from calculation of earnings per share (in shares)	4,225	5,715	6,137	5,366
Convertible Senior Notes | Convertible Senior Note due 2023, 0.5%
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Initial Conversion Price	$ 44.33		$ 44.33		$ 44.33
Convertible Senior Notes | Convertible Senior Notes due 2024 & 2026, 0.50%, 1.0%
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Initial Conversion Price	$ 189.36		$ 189.36