Nature of operations and summary of significant accounting policies (Reorganization Items) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Abstract]
Loss on the settlement of liabilities subject to compromise	$ 0	$ 0	$ 0	$ 48
Professional fees	530	493	1,306	1,962
Total reorganization items	$ 530	$ 493	$ 1,306	$ 2,010