Loss per common share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Numerator:
Net loss	$ (3,255)	$ (5,649)
Denominator:
Basic-weighted average shares (in shares)	17,924,000	17,727,000
Effect of dilutive stock options (in shares)	0	0
Diluted-weighted average shares (in shares)	17,924,000	17,727,000
Basic loss per common share (in dollars per share)	$ (0.18)	$ (0.32)
Diluted loss per common share (in dollars per share)	$ (0.18)	$ (0.32)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options outstanding (in shares)	333,000	433,000
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred stock units granted	478,000	433,000