Major classes of assets and liabilities held for sale (Details 2) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Current assets:
Total current assets held for sale	$ 430	$ 430	$ 458
Noncurrent assets:
Total noncurrent assets held for sale	2,087	2,087	4,392
Current liabilities:
Total current liabilities held for sale	3,657	4,001	11,726
Discontinued operations, held-for-sale or disposed of by sale
Current assets:
Receivables, net	430	430	458
Income taxes receivable (a)	0	0	1,858
Total current assets held for sale	430	430	2,316
Noncurrent assets:
Net property, plant and equipment	0	0	1,631
Deferred income taxes	1,926	1,926	2,637
Other	161	161	161
Total noncurrent assets held for sale	2,087	2,087	4,429
Total assets held for sale	2,517	2,517	6,745
Current liabilities:
Accounts payable	0	80	0
Taxes payable	1,295	1,451	10,774
Other accrued liabilities	2,362	2,470	2,810
Total current liabilities held for sale	3,657	4,001	13,584
Noncurrent liabilities:
Deferred income taxes (b)	0	0	37
Total noncurrent liabilities held for sale	0	0	37
Total liabilities held for sale	$ 3,657	$ 4,001	$ 13,621