Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Segments [Abstract]
Number of reportable segments			2
Evaluation of financial performance for each segment [Abstract]
Revenues	$ 29,977	$ 26,931	$ 58,557	$ 52,028
Depreciation and amortization	1,577	1,476	3,121	2,972
Income from operations	1,883	2,173	4,243	3,406
Other income (expense)	70	39	66	31
Income before income tax expense	1,953	2,212	4,309	3,437
Capital expenditures for assets	2,468	1,979	3,067	3,465
Assets	80,496		80,496		76,854
Revenue from External Customer [Line Items]
Revenue from external customers	6,536	5,659	12,979	11,244
POC on Site Testing Products [Member]
Revenue from External Customer [Line Items]
Revenue from external customers	6,261	5,248	11,859	10,107
Contract Manufacturing Services [Member]
Revenue from External Customer [Line Items]
Revenue from external customers	42	214	683	750
Other Diagnostic Products [Member]
Revenue from External Customer [Line Items]
Revenue from external customers	233	197	437	387
Laboratory Services [Member]
Evaluation of financial performance for each segment [Abstract]
Revenues	23,441	21,272	45,578	40,784
Depreciation and amortization	1,342	1,271	2,656	2,567
Income from operations	443	1,028	1,425	1,130
Capital expenditures for assets	2,030	1,668	2,539	2,740
Assets	68,312		68,312		65,739
Product Sales [Member]
Evaluation of financial performance for each segment [Abstract]
Revenues	6,536	5,659	12,979	11,244
Depreciation and amortization	235	205	465	405
Income from operations	1,440	1,145	2,818	2,276
Capital expenditures for assets	438	311	528	725
Assets	10,873		10,873		8,339
Corporate (unallocated) [Member]
Evaluation of financial performance for each segment [Abstract]
Other income (expense)	70	39	66	31
Assets	$ 1,311		$ 1,311		$ 2,776