Equity - Statement of Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Increase (Decrease) in Stockholders' Equity
Balance at the beginning of the period	$ 374,512	$ 437,775
Net loss	(567)	(18,530)
Other comprehensive income, net of tax	153	38
Share-based compensation expense	3,646	3,157
Net issuance under employee stock plans	(680)	(642)
Balance at the end of the period	377,064	421,798
Common Stock
Increase (Decrease) in Stockholders' Equity
Balance at the beginning of the period	$ 490	$ 485
Balance (in shares)	48,994	48,547
Net issuance under employee stock plans	$ 4	$ 2
Net issuance under employee stock plans (in shares)	434	128
Balance at the end of the period	$ 494	$ 487
Balance (in shares)	49,428	48,675
Treasury Stock
Increase (Decrease) in Stockholders' Equity
Balance at the beginning of the period		$ (5,872)
Balance (in shares)		523
Net issuance under employee stock plans		$ 5,872
Net issuance under employee stock plans (in shares)		(523)
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity
Balance at the beginning of the period	$ 1,071,058	$ 1,061,325
Share-based compensation expense	3,646	3,157
Net issuance under employee stock plans	(684)	(6,303)
Balance at the end of the period	1,074,020	1,058,179
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity
Balance at the beginning of the period	(698,930)	(619,983)
Net loss	(567)	(18,530)
Net issuance under employee stock plans		(213)
Balance at the end of the period	(699,497)	(638,726)
Accumulated Other Comprehensive Income
Increase (Decrease) in Stockholders' Equity
Balance at the beginning of the period	1,894	1,820
Other comprehensive income, net of tax	153	38
Balance at the end of the period	$ 2,047	$ 1,858