Short-term notes payable (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
Contractual Obligations, payments due by period
Contractual obligations, short-term notes payable due in 2012	$ 1,225
Contractual obligations, short-term notes payable due in 2013	1,000
Contractual obligations, short-term notes payable due in 2014	0
Contractual obligations, short-term notes payable due in 2015	0
Contractual obligations, short-term notes payable due in 2016	0
Contractual obligations, short-term notes payable due thereafter	0
Contractual obligations, short-term notes payable	$ 2,225