Major classes of assets under capital leases (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets under capital leases
Assets under capital leases, gross	$ 997	$ 1,021
Less: Accumulated depreciation	(905)	(829)
Total assets under capital leases	92	192
Land and buildings
Assets under capital leases
Assets under capital leases, gross	0	0
Machinery and equipment
Assets under capital leases
Assets under capital leases, gross	889	918
Fixtures, fittings and office equipment
Assets under capital leases
Assets under capital leases, gross	$ 108	$ 103