Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2011	$ 31,953
Balance, shares at Dec. 31, 2011		30,747
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	0
Common Stocks, Including Additional Paid in Capital		6,103
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16,883		16,883
Unrealized loss on marketable securities, net of income tax benefit of $(11)	0
Foreign currency translation adjustment, including income tax expense (benefit)	(83)			(83)
Reclassification of foreign currency translation gains to income upon substantial liquidation of subsidiaries				(6,170)
Foreign currency translation tax provision (benefit)	(9)
Stock-based compensation expense	630	630
Common stock issued under equity compensation plan, shares		177
Common stock issued under equity compensation plan	113	113
Retained earnings			36,598
Accumulated other comprehensive income (loss)				625
Balance at Dec. 31, 2012	43,326
Balance, shares at Dec. 31, 2012		30,924
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	0
Common Stocks, Including Additional Paid in Capital		6,769
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	47,954		47,954
Unrealized loss on marketable securities, net of income tax benefit of $(11)	0
Foreign currency translation adjustment, including income tax expense (benefit)	(381)			(381)
Foreign currency translation tax provision (benefit)	20
Stock-based compensation expense	454	454
Common stock issued under equity compensation plan, shares		238
Common stock issued under equity compensation plan	357	357
Tax deficiency related to stock-based awards	(145)
Retained earnings	84,552		84,552
Accumulated other comprehensive income (loss)	244			244
Balance at Dec. 31, 2013	91,565
Balance, shares at Dec. 31, 2013		31,162
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	(11)
Common Stocks, Including Additional Paid in Capital		8,033
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,795		18,795
Unrealized loss on marketable securities, net of income tax benefit of $(11)	(18)			(18)
Foreign currency translation adjustment, including income tax expense (benefit)	(534)			(534)
Foreign currency translation tax provision (benefit)	15
Stock-based compensation expense	1,066	1,066
Common stock issued under equity compensation plan, shares		171
Common stock issued under equity compensation plan	378	378
Tax deficiency related to stock-based awards	(180)
Retained earnings	103,347		103,347
Accumulated other comprehensive income (loss)	(308)			(308)
Balance at Dec. 31, 2014	$ 111,072
Balance, shares at Dec. 31, 2014		31,333