CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total		Common Shares	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2017	$ 311,545		$ 423,856	$ 33,309	$ (127,740)	$ (17,880)
Balance (in shares) at Dec. 31, 2017			34,595
Net income	22,911	[1]			22,911
Redeemable noncontrolling interest redemption value adjustment	(5,096)	[1]			(5,096)
Common stock issued under stock plans (in shares)			166
Shares withheld for taxes on vested stock awards	(3,367)			(3,367)
Shares withheld for taxes on vested stock awards (in shares)			(61)
Repurchases of common stock	(1,929)			(1,929)
Repurchases of common stock (in shares)			(29)
Share-based compensation	3,780			3,780
Adoption of ASU 2016-16 | ASU 2016-16	(2,242)				(2,242)
Other comprehensive income, net of tax	(1,237)					(1,237)
Balance at Jun. 29, 2018	324,365		$ 423,856	31,793	(112,167)	(19,117)
Balance (in shares) at Jun. 29, 2018			34,671
Balance at Mar. 30, 2018	318,610		$ 423,856	32,549	(123,470)	(14,325)
Balance (in shares) at Mar. 30, 2018			34,685
Net income	11,000	[1]			11,000
Redeemable noncontrolling interest redemption value adjustment	303	[1]			303
Common stock issued under stock plans (in shares)			25
Shares withheld for taxes on vested stock awards	(563)			(563)
Shares withheld for taxes on vested stock awards (in shares)			(10)
Repurchases of common stock	(1,929)			(1,929)
Repurchases of common stock (in shares)			(29)
Share-based compensation	1,736			1,736
Other comprehensive income, net of tax	(4,792)					(4,792)
Balance at Jun. 29, 2018	324,365		$ 423,856	31,793	(112,167)	(19,117)
Balance (in shares) at Jun. 29, 2018			34,671
Balance at Dec. 31, 2018	368,255		$ 423,856	46,018	(79,092)	(22,527)
Balance (in shares) at Dec. 31, 2018			34,886
Net income	22,633	[2]			22,633
Common stock issued under stock plans (in shares)			209
Shares withheld for taxes on vested stock awards	(6,719)			(6,719)
Shares withheld for taxes on vested stock awards (in shares)			(84)
Repurchases of common stock	(3,339)			(3,339)
Repurchases of common stock (in shares)			(39)
Share-based compensation	5,105			5,105
Other comprehensive income, net of tax	247					247
Balance at Jun. 28, 2019	386,182		$ 423,856	41,065	(56,459)	(22,280)
Balance (in shares) at Jun. 28, 2019			34,972
Balance at Mar. 29, 2019	379,701		$ 423,856	42,855	(66,839)	(20,171)
Balance (in shares) at Mar. 29, 2019			34,998
Net income	10,380	[2]			10,380
Common stock issued under stock plans (in shares)			23
Shares withheld for taxes on vested stock awards	(829)			(829)
Shares withheld for taxes on vested stock awards (in shares)			(10)
Repurchases of common stock	(3,339)			(3,339)
Repurchases of common stock (in shares)			(39)
Share-based compensation	2,378			2,378
Other comprehensive income, net of tax	(2,109)					(2,109)
Balance at Jun. 28, 2019	$ 386,182		$ 423,856	$ 41,065	$ (56,459)	$ (22,280)
Balance (in shares) at Jun. 28, 2019			34,972

[1] 53,968 non-GAAP EPS performance-based restricted stock units granted to certain members of the executive management team were considered contingently issuable shares and were excluded from the calculation of the denominator as the contingent conditions had not been met as of June 29, 2018.

[2] 45,252 non-GAAP EPS performance-based restricted stock units granted to certain members of the executive management team and 213,219 shares of restricted stock issued to Laser Quantum former non-controlling interest holders are considered contingently issuable shares and are excluded from the calculation of the denominator as the contingent conditions had not been met as of June 28, 2019.