Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance at Mar. 31, 2018	$ 323,410	$ 640	$ 244,462	$ 78,708	$ (400)
Balance, Shares at Mar. 31, 2018		63,995
Common stock issued under stock plans, net of shares withheld for taxes	(202)	$ 2	(204)
Common stock issued under stock plans, net of shares withheld for taxes, Shares		225
Stock-based compensation	3,116		3,116
Cumulative effect adjustment related to the adoption of ASC 606	8,419			8,419
Other comprehensive income:
Translation adjustments	(499)				(499)
Net income	2,648			2,648
Balance at Jun. 30, 2018	336,892	$ 642	247,374	89,775	(899)
Balance, Shares at Jun. 30, 2018		64,220
Balance at Mar. 31, 2018	323,410	$ 640	244,462	78,708	(400)
Balance, Shares at Mar. 31, 2018		63,995
Other comprehensive income:
Translation adjustments	(881)
Net income	20,566
Balance at Dec. 31, 2018	365,370	$ 647	258,311	107,693	(1,281)
Balance, Shares at Dec. 31, 2018		64,704
Balance at Jun. 30, 2018	336,892	$ 642	247,374	89,775	(899)
Balance, Shares at Jun. 30, 2018		64,220
Common stock issued under stock plans, net of shares withheld for taxes	2,106	$ 2	2,104
Common stock issued under stock plans, net of shares withheld for taxes, Shares		162
Stock-based compensation	4,135		4,135
Other comprehensive income:
Translation adjustments	(793)				(793)
Net income	13,094			13,094
Balance at Sep. 30, 2018	355,434	$ 644	253,613	102,869	(1,692)
Balance, Shares at Sep. 30, 2018		64,382
Common stock issued under stock plans, net of shares withheld for taxes	3	$ 3
Common stock issued under stock plans, net of shares withheld for taxes, Shares		322
Stock-based compensation	4,698		4,698
Other comprehensive income:
Translation adjustments	411				411
Net income	4,824			4,824
Balance at Dec. 31, 2018	365,370	$ 647	258,311	107,693	(1,281)
Balance, Shares at Dec. 31, 2018		64,704
Balance at Mar. 31, 2019	375,946	$ 648	264,908	111,621	(1,231)
Balance, Shares at Mar. 31, 2019		64,838
Common stock issued under stock plans, net of shares withheld for taxes	(1,305)	$ 6	(1,311)
Common stock issued under stock plans, net of shares withheld for taxes, Shares		545
Stock-based compensation	4,891		4,891
Other comprehensive income:
Translation adjustments	54				54
Net income	1,244			1,244
Balance at Jun. 30, 2019	380,830	$ 654	268,488	112,865	(1,177)
Balance, Shares at Jun. 30, 2019		65,383
Balance at Mar. 31, 2019	375,946	$ 648	264,908	111,621	(1,231)
Balance, Shares at Mar. 31, 2019		64,838
Other comprehensive income:
Translation adjustments	(192)
Net income	11,740
Balance at Dec. 31, 2019	399,756	$ 657	277,161	123,361	(1,423)
Balance, Shares at Dec. 31, 2019		65,701
Balance at Jun. 30, 2019	380,830	$ 654	268,488	112,865	(1,177)
Balance, Shares at Jun. 30, 2019		65,383
Common stock issued under stock plans, net of shares withheld for taxes	44		44
Common stock issued under stock plans, net of shares withheld for taxes, Shares		53
Stock-based compensation	4,316		4,316
Other comprehensive income:
Translation adjustments	(143)				(143)
Net income	6,081			6,081
Balance at Sep. 30, 2019	391,128	$ 654	272,848	118,946	(1,320)
Balance, Shares at Sep. 30, 2019		65,436
Common stock issued under stock plans, net of shares withheld for taxes	(305)	$ 3	(308)
Common stock issued under stock plans, net of shares withheld for taxes, Shares		265
Stock-based compensation	4,621		4,621
Other comprehensive income:
Translation adjustments	(103)				(103)
Net income	4,415			4,415
Balance at Dec. 31, 2019	$ 399,756	$ 657	$ 277,161	$ 123,361	$ (1,423)
Balance, Shares at Dec. 31, 2019		65,701