Condensed Consolidated Statements of Stockholders' Equity and Comprehensive Income (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Comprehensive Income Total
Beginning Balance, Value at Dec. 31, 2008	$ 70,142	$ 981	$ (1,178)	$ 111,641	$ (30,199)	$ (11,103)
Beginning Balance, Issued Shares at Dec. 31, 2008		30,019,365
Beginning Balance, Treasury Shares at Dec. 31, 2008			(179,235)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	38,822				38,822		38,822
Cumulative translation adjustment	11,452					11,452	11,452
Comprehensive income							50,274
Exercise of stock options, Shares		302,163
Exercise of stock options, Value	1,565	10		1,555
Deferred compensation and amortization related to options and restricted stock	1,369			1,369
Repurchases of common stock, Shares		(48,672)
Repurchase of treasury stock, Shares			(31,950)
Repurchases of common stock, Value	(505)	(2)	(205)	(298)
Retirement of treasury stock, Shares		(170,676)	170,676
Retirement of treasury stock, Value	0		1,307	(1,307)
Conversion of principal and interest on Convertible promisorry notes, Shares		2,790,186
Conversion of principal and interest on Convertible promissary notes, Value	22,355	93		22,262
Effect 3-1 stock split	0	2,295		(2,295)
Imputed interest on issuance of convertible debt	534			534
Shares subscribed for business acquisition, Shares		1,488,984
Shares subscribed for business acquisition, Value	25,000	50		24,950
Vesting of restricted stock, Shares		93,258
Vesting of restricted stock, Value	9	16		(7)
Ending Balance, Value at Dec. 31, 2009	170,743	3,443	(76)	158,404	8,623	349
Ending Balance, Issued Shares at Dec. 31, 2009		34,474,608
Ending Balance, Treasury Shares at Dec. 31, 2009			(40,509)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	59,019				59,019		59,019
Cumulative translation adjustment	6,530					6,530	6,530
Comprehensive income							65,549
Exercise of stock options, Shares		1,252,785
Exercise of stock options, Value	1,236	125		1,111
Deferred compensation and amortization related to options and restricted stock	1,850			1,850
Repurchases of common stock, Shares		(669,978)
Repurchases of common stock, Value	(10,650)	(67)		(10,583)
Conversion of principal and interest on Convertible promisorry notes, Shares		760,040
Conversion of principal and interest on Convertible promissary notes, Value	1,712	76		1,636
APIC Adjustment for stock option	828			828
Vesting of restricted stock, Shares		240,336
Vesting of restricted stock, Value	0	25		(25)
Ending Balance, Value at Dec. 31, 2010	231,268	3,602	(76)	153,221	67,642	6,879
Ending Balance, Issued Shares at Dec. 31, 2010		36,057,791
Ending Balance, Treasury Shares at Dec. 31, 2010			(40,509)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	71,378				71,378		71,378
Cumulative translation adjustment	(11,403)					(11,403)	(11,403)
Comprehensive income							59,975
Exercise of stock options, Shares		69,509
Exercise of stock options, Value	51	8		43
Repurchases of common stock, Shares		(3,510,973)
Repurchases of common stock, Value	(63,659)	(351)		(63,308)
Conversion of principal and interest on Convertible promisorry notes, Shares
Conversion of principal and interest on Convertible promissary notes, Value	(1,851)			(1,851)
Deferred compensation and amortization related to options and restricted stock	2,205			2,205
Shares subscribed for business acquisition, Shares		3,650,914
Shares subscribed for business acquisition, Value	87,476	365		87,111
APIC Adjustment for stock option	2,111			2,111
Vesting of restricted stock, Shares		151,144
Vesting of restricted stock, Value	0	14		(14)
Dividends paid	(1,461)				(1,461)
Ending Balance, Value at Dec. 31, 2011	$ 316,115	$ 3,638	$ (76)	$ 179,518	$ 137,559	$ (4,524)
Ending Balance, Issued Shares at Dec. 31, 2011		36,418,385
Ending Balance, Treasury Shares at Dec. 31, 2011			(40,509)