Identifiable intangible assets (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Software costs capitalized	$ 965,000	$ 942,000	$ 1,626,000	$ 1,622,000
Remaining estimated economic life of the product	3 years	7 years	3 years	7 years
Amortization of capitalized software costs	400,000	398,000	492,000	764,000
Amortization of identifiable intangible assets		150,000		303,000
Components of identifiable intangible assets [Abstract]
Intangible assets - gross	15,414,000		15,414,000		13,788,000
Less accumulated amortization	(2,533,000)		(2,533,000)		(2,041,000)
Intangible assets - net	12,881,000		12,881,000		11,747,000
Future amortization of intangible assets assuming straight-line amortization of capitalized software costs [Abstract]
2013	783,000		783,000
2014	1,626,000		1,626,000
2015	1,547,000		1,547,000
2016	1,518,000		1,518,000
2017	1,493,000		1,493,000
2018	1,419,000		1,419,000
Thereafter	2,695,000		2,695,000
Total	11,081,000		11,081,000
Acquired and internally developed software costs [Member]
Components of identifiable intangible assets [Abstract]
Intangible assets - gross	13,614,000		13,614,000		11,988,000
Trademarks (non-amortizable) [Member]
Components of identifiable intangible assets [Abstract]
Intangible assets - gross	$ 1,800,000		$ 1,800,000		$ 1,800,000