Condensed Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
BALANCE - value at Dec. 31, 2017	$ 221,296	$ 6	$ (1,433)	$ 289,821	$ (67,101)	$ 3
BALANCE - shares at Dec. 31, 2017		61,897	(278)
Cumulative effect of recent accounting pronouncements	(1,577)				(1,577)
Share-based compensation, value	2,264			2,264
Share-based compensation, shares		72
Vesting of restricted stock units, including impact of shares withheld for taxes, value	(1,060)			(1,060)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares		486
Exercise of options and purchases from employee stock plans, value	443			443
Exercise of options and purchases from employee stock plans, shares		128
Net income (loss)	(10,295)				(10,295)
Other comprehensive income—net of tax	443					443
BALANCE - value at Jun. 30, 2018	211,514	$ 6	$ (1,433)	291,468	(78,973)	446
BALANCE - shares at Jun. 30, 2018		62,583	(278)
BALANCE - value at Mar. 31, 2018	211,502	$ 6	$ (1,433)	290,298	(77,999)	630
BALANCE - shares at Mar. 31, 2018		62,485	(278)
Share-based compensation, value	1,255			1,255
Share-based compensation, shares		32
Vesting of restricted stock units, including impact of shares withheld for taxes, value	(124)			(124)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares		56
Exercise of options and purchases from employee stock plans, value	39			39
Exercise of options and purchases from employee stock plans, shares		10
Net income (loss)	(974)				(974)
Other comprehensive income—net of tax	(184)					(184)
BALANCE - value at Jun. 30, 2018	211,514	$ 6	$ (1,433)	291,468	(78,973)	446
BALANCE - shares at Jun. 30, 2018		62,583	(278)
BALANCE - value at Dec. 31, 2018	214,928	$ 6	$ (1,433)	295,135	(74,971)	(3,809)
BALANCE - shares at Dec. 31, 2018		62,830	(278)
Cumulative effect of recent accounting pronouncements	2,802				2,802
Share-based compensation, value	4,530			4,530
Share-based compensation, shares		45
Vesting of restricted stock units, including impact of shares withheld for taxes, value	(2,929)			(2,929)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares		554
Exercise of options and purchases from employee stock plans, value	3,756			3,756
Exercise of options and purchases from employee stock plans, shares		618
Cancellation of treasury stock			$ 1,433	(1,173)	(261)
Cancellation of treasury stock, shares		(278)	278
Net income (loss)	25,414				25,414
Other comprehensive income—net of tax	2,977					2,977
BALANCE - value at Jun. 30, 2019	251,478	$ 6		299,320	(47,016)	(832)
BALANCE - shares at Jun. 30, 2019		63,769
BALANCE - value at Mar. 31, 2019	239,277	$ 6	$ (1,433)	296,774	(55,001)	(1,069)
BALANCE - shares at Mar. 31, 2019		63,600	(278)
Share-based compensation, value	2,329			2,329
Share-based compensation, shares		14
Vesting of restricted stock units, including impact of shares withheld for taxes, value	(741)			(741)
Vesting of restricted stock units, including impact of shares withheld for taxes, shares		101
Exercise of options and purchases from employee stock plans, value	2,130			2,130
Exercise of options and purchases from employee stock plans, shares		332
Cancellation of treasury stock			$ 1,433	(1,173)	(261)
Cancellation of treasury stock, shares		(278)	278
Net income (loss)	8,246				8,246
Other comprehensive income—net of tax	237					237
BALANCE - value at Jun. 30, 2019	$ 251,478	$ 6		$ 299,320	$ (47,016)	$ (832)
BALANCE - shares at Jun. 30, 2019		63,769