Nature of operations and summary of significant accounting policies (Schedule of Reorganization Items) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accounting Policies [Abstract]
Loss on the settlement of liabilities subject to compromise	$ 0	$ 0	$ 0	$ 48
Professional fees	313	480	776	1,469
Total reorganization items	$ 313	$ 480	$ 776	$ 1,517