Identifiable intangible assets (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Software costs capitalized	$ 661,000	$ 679,000
Remaining estimated economic life of the product	3 years	7 years
Amortization of capitalized software costs	92,000	366,000
Amortization of identifiable intangible assets		153,000
Components of identifiable intangible assets [Abstract]
Intangible assets - gross	14,449,000		13,788,000
Less accumulated amortization	(2,133,000)		(2,041,000)
Intangible assets - net	12,316,000		11,747,000
Future amortization of intangible assets assuming straight-line amortization of capitalized software costs [Abstract]
2013	1,241,000
2014	1,667,000
2015	1,567,000
2016	1,539,000
2017	1,514,000
Thereafter	2,988,000
Total	10,516,000
Acquired and internally developed software costs [Member]
Components of identifiable intangible assets [Abstract]
Intangible assets - gross	12,649,000		11,988,000
Trademarks (non-amortizable) [Member]
Components of identifiable intangible assets [Abstract]
Intangible assets - gross	$ 1,800,000		$ 1,800,000