Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($)	Common Stock [Member]	Additional Paid-in Capital Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment | ASU 2016-01 [Member]	$ 0	$ 0	$ 746,000	$ (746,000)	$ 0
Beginning balance at Mar. 31, 2018	$ 189,000	213,609,000	78,510,000	(5,428,000)	286,880,000
Beginning balance (in shares) at Mar. 31, 2018	18,893,102
Adjusted beginning balance at Mar. 31, 2018	$ 189,000	213,609,000	79,256,000	(6,174,000)	286,880,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation recognized under employee stock plans	0	941,000	0	0	941,000
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes	$ 0	(192,000)	0	0	(192,000)
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes (in shares)	23,006
Foreign currency translation	$ 0	0	0	(715,000)	(715,000)
Net income (loss)	0	0	(5,495,000)	0	(5,495,000)
Ending balance at Jun. 30, 2018	$ 189,000	214,358,000	73,761,000	(6,889,000)	281,419,000
Ending balance (in shares) at Jun. 30, 2018	18,916,108
Beginning balance at Mar. 31, 2018	$ 189,000	213,609,000	78,510,000	(5,428,000)	286,880,000
Beginning balance (in shares) at Mar. 31, 2018	18,893,102
Adjusted beginning balance at Mar. 31, 2018	$ 189,000	213,609,000	79,256,000	(6,174,000)	286,880,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation					(1,019,000)
Net income (loss)					(5,084,000)
Ending balance at Dec. 31, 2018	$ 188,000	212,621,000	74,172,000	(7,193,000)	279,788,000
Ending balance (in shares) at Dec. 31, 2018	18,812,102
Beginning balance at Jun. 30, 2018	$ 189,000	214,358,000	73,761,000	(6,889,000)	281,419,000
Beginning balance (in shares) at Jun. 30, 2018	18,916,108
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation recognized under employee stock plans	$ 0	1,180,000	0	0	1,180,000
Exercise of stock options	$ 1,000	243,000	0	0	244,000
Exercise of stock options (in shares)	39,032
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes	$ 0	(128,000)	0	0	(128,000)
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes (in shares)	8,152
Repurchase and cancellation of treasury stock, including fees	$ (2,000)	(4,060,000)	0	0	(4,062,000)
Repurchase and cancellation of treasury stock, including fees (in shares)	(163,815)
Foreign currency translation	$ 0	0	0	(2,000)	(2,000)
Net income (loss)	0	0	3,513,000	0	3,513,000
Ending balance at Sep. 30, 2018	$ 188,000	211,593,000	77,274,000	(6,891,000)	282,164,000
Ending balance (in shares) at Sep. 30, 2018	18,799,477
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation recognized under employee stock plans	$ 0	1,030,000	0	0	1,030,000
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes	$ 0	(2,000)	0	0	(2,000)
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes (in shares)	12,625
Foreign currency translation	$ 0	0	0	(302,000)	(302,000)
Net income (loss)	0	0	(3,102,000)	0	(3,102,000)
Ending balance at Dec. 31, 2018	$ 188,000	212,621,000	74,172,000	(7,193,000)	279,788,000
Ending balance (in shares) at Dec. 31, 2018	18,812,102
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment | ASU 2016-01 [Member]					0
Beginning balance at Mar. 31, 2019	$ 188,000	215,047,000	71,407,000	(6,887,000)	$ 279,755,000
Beginning balance (in shares) at Mar. 31, 2019	18,817,400				18,817,400
Adjusted beginning balance at Mar. 31, 2019				(6,887,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation recognized under employee stock plans	$ 0	988,000	0	0	$ 988,000
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes	$ 1,000	(363,000)	0	0	(362,000)
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes (in shares)	36,872
Foreign currency translation	$ 0	0	0	599,000	599,000
Net income (loss)	0	0	(6,151,000)	0	(6,151,000)
Ending balance at Jun. 30, 2019	$ 189,000	215,672,000	65,256,000	(6,288,000)	274,829,000
Ending balance (in shares) at Jun. 30, 2019	18,854,272
Beginning balance at Mar. 31, 2019	$ 188,000	215,047,000	71,407,000	(6,887,000)	$ 279,755,000
Beginning balance (in shares) at Mar. 31, 2019	18,817,400				18,817,400
Adjusted beginning balance at Mar. 31, 2019				(6,887,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation					$ 1,183,000
Net income (loss)					903,000
Ending balance at Dec. 31, 2019	$ 190,000	217,530,000	72,310,000	(5,704,000)	$ 284,326,000
Ending balance (in shares) at Dec. 31, 2019	18,965,030				18,965,030
Beginning balance at Jun. 30, 2019	$ 189,000	215,672,000	65,256,000	(6,288,000)	$ 274,829,000
Beginning balance (in shares) at Jun. 30, 2019	18,854,272
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation recognized under employee stock plans	$ 0	1,053,000	0	0	1,053,000
Exercise of stock options	$ 0	405,000	0	0	405,000
Exercise of stock options (in shares)	52,800
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes	$ 0	(700,000)	0	0	(700,000)
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes (in shares)	37,814
Foreign currency translation	$ 0	0	0	(431,000)	(431,000)
Net income (loss)	0	0	6,189,000	0	6,189,000
Ending balance at Sep. 30, 2019	$ 189,000	216,430,000	71,445,000	(6,719,000)	281,345,000
Ending balance (in shares) at Sep. 30, 2019	18,944,886
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation recognized under employee stock plans	$ 0	1,071,000	0	0	1,071,000
Exercise of stock options	$ 1,000	29,000	0	0	30,000
Exercise of stock options (in shares)	3,600
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes	$ 0	0	0	0	0
Issuance of common stock upon vesting of RSUs, net of shares withheld for employee taxes (in shares)	16,544
Foreign currency translation	$ 0	0	0	1,015,000	1,015,000
Net income (loss)	0	0	865,000	0	865,000
Ending balance at Dec. 31, 2019	$ 190,000	$ 217,530,000	$ 72,310,000	$ (5,704,000)	$ 284,326,000
Ending balance (in shares) at Dec. 31, 2019	18,965,030				18,965,030