Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2016	26,504,868
Balance at Dec. 31, 2016	$ 26	$ 213,857	$ 176,703	$ (10,753)	$ 379,833
Common shares issued on exercise of options and other (in shares)	283,449
Common shares issued on exercise of options and other	$ 1	8,603	0	0	8,604
Common shares issued for RAPID acquisition (in shares)	118,140
Common shares issued for RAPID acquisition	$ 1	11,335	0	0	11,336
Stock-based compensation expense	$ 0	8,558	0	0	8,558
Repurchases of Common Stock (in shares)	(77,806)
Repurchases of Common Stock	$ (1)	(628)	(3,784)	0	(4,413)
Net income	0	0	51,778	0	51,778
Other Comprehensive (Loss) Income, net of tax
Foreign currency translation adjustments	$ 0	0	0	5,519	5,519
Comprehensive income					57,297
Common shares issued on exercise of options and other (in shares)	283,449
Common shares issued on exercise of options and other	$ 1	8,603	0	0	8,604
Stock-based compensation expense	$ 0	8,558	0	0	8,558
Repurchases of Common Stock (in shares)	(77,806)
Repurchases of Common Stock	$ (1)	(628)	(3,784)	0	(4,413)
Net income	$ 0	0	51,778	0	51,778
Balance (in shares) at Dec. 31, 2017	26,828,651
Balance at Dec. 31, 2017	$ 27	241,725	224,697	(5,234)	461,215
Common shares issued on exercise of options and other (in shares)	260,694
Common shares issued on exercise of options and other	$ 0	6,791	0	0	6,791
Stock-based compensation expense	$ 0	10,928	0	0	10,928
Repurchases of Common Stock (in shares)	(104,598)
Repurchases of Common Stock	$ 0	(942)	(11,287)	0	(12,229)
Net income	0	0	76,588	0	76,588
Other Comprehensive (Loss) Income, net of tax
Foreign currency translation adjustments	$ 0	0	0	(3,258)	(3,258)
Comprehensive income					73,330
Common shares issued on exercise of options and other (in shares)	260,694
Common shares issued on exercise of options and other	$ 0	6,791	0	0	6,791
Stock-based compensation expense	$ 0	10,928	0	0	10,928
Repurchases of Common Stock (in shares)	(104,598)
Repurchases of Common Stock	$ 0	(942)	(11,287)	0	(12,229)
Net income	$ 0	0	76,588	0	$ 76,588
Balance (in shares) at Dec. 31, 2018	26,984,747				26,984,747
Balance at Dec. 31, 2018	$ 27	258,502	291,460	(8,492)	$ 541,497
Other Comprehensive (Loss) Income, net of tax
Revenue recognition transition adjustment	$ 0	0	1,462	0	1,462
Common shares issued on exercise of options and other (in shares)	128,174
Common shares issued on exercise of options and other	$ 0	1,904	0	0	1,904
Stock-based compensation expense	$ 0	10,781	0	0	10,781
Repurchases of Common Stock (in shares)	(326,462)
Repurchases of Common Stock	$ 0	(3,128)	(30,393)	0	(33,521)
Net income	0	0	63,655	0	63,655
Foreign currency translation adjustments	$ 0	0	0	1,474	1,474
Comprehensive income					65,129
Common shares issued on exercise of options and other (in shares)	128,174
Common shares issued on exercise of options and other	$ 0	1,904	0	0	1,904
Stock-based compensation expense	$ 0	10,781	0	0	10,781
Repurchases of Common Stock (in shares)	(326,462)
Repurchases of Common Stock	$ 0	(3,128)	(30,393)	0	(33,521)
Net income	$ 0	0	63,655	0	$ 63,655
Balance (in shares) at Dec. 31, 2019	26,786,459				26,786,459
Balance at Dec. 31, 2019	$ 27	$ 268,059	$ 324,722	$ (7,018)	$ 585,790