Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Numerator:
Net income (loss) attributable to common stockholders	$ (35,293)	$ (3,219)	$ (50,766)	$ 2,695
Denominator:
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, basic	66,039	62,613	65,804	62,271
Effect of dilutive securities:
Convertible senior notes	0	0	0	2,333
Contingently issuable shares (in shares)	0	0	0	6
Employee stock awards (in shares)	0	0	0	3,384
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, diluted	66,039	62,613	65,804	67,994
Net income (loss) per share attributable to common stockholders, basic (in dollars per share)	$ (0.53)	$ (0.05)	$ (0.77)	$ 0.04
Net income (loss) per share attributable to common stockholders, diluted (in dollars per share)	$ (0.53)	$ (0.05)	$ (0.77)	$ 0.04
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from calculation of earnings per share (in shares)	10,140	9,939	10,212	249
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from calculation of earnings per share (in shares)	4,003	4,751	4,075	249
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from calculation of earnings per share (in shares)	6,137	5,188	6,137	0
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