Quarterly Results (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly financial data
Revenue	$ 53,109	$ 52,087	$ 51,658	$ 51,649	$ 49,944	$ 51,751	$ 50,704	$ 50,718	$ 208,503	$ 203,117	$ 184,081
Operating expenses:
Cost of revenue	34,399	32,461	33,312	34,218	34,240	34,125	34,523	34,594	134,390	137,482	126,069
Selling, general and administrative expenses	13,952	13,242	12,696	12,637	11,958	12,417	12,297	12,430	52,527	49,102	40,735
Depreciation of property and equipment	2,276	1,716	1,579	1,513	1,542	1,464	1,214	1,181	7,084	5,401	4,903
Amortization of intangible assets	2,007	1,431	1,459	2,327	1,464	1,277	1,129	1,121	7,224	4,991	4,131
Total operating expenses	52,634	48,850	49,046	50,695	49,204	49,283	49,163	49,326	201,225	196,976	175,838
Operating income	475	3,237	2,612	954	740	2,468	1,541	1,392	7,278	6,141	8,243
Foreign currency transaction (gains) losses on short-term intercompany balances	(187)	(348)	497	(339)	241	1,055	(431)	(448)	377	(417)	(422)
Interest expense (income), net	(582)	515	529	504	393	398	478	347	1,116	1,904	1,451
Earnings before income taxes	1,244	3,070	1,586	789	106	1,015	1,494	1,493	6,689	4,108	5,135
Income tax expense (benefit)	(289)	505	584	497	(1,206)	593	784	1,121	1,297	1,292	1,882
Net earnings	$ 1,533	$ 2,565	$ 1,002	$ 292	$ 1,312	$ 422	$ 710	$ 372	$ 5,392	$ 2,816	$ 3,253
Basic earnings per common share	$ 0.06	$ 0.10	$ 0.04	$ 0.01	$ 0.05	$ 0.02	$ 0.03	$ 0.02	$ 0.21	$ 0.11	$ 0.14
Diluted earnings per common share	$ 0.06	$ 0.10	$ 0.04	$ 0.01	$ 0.05	$ 0.02	$ 0.03	$ 0.02	$ 0.21	$ 0.11	$ 0.13