Major classes of assets and liabilities held for sale E&P (Details 3) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Current assets:
Total current assets held for sale	$ 571	$ 479	$ 304
Noncurrent assets:
Total noncurrent assets held for sale	1,835	4,392	64,333
Current liabilities:
Total current liabilities held for sale	7,959	11,993	5,749
Exploration and production | Discontinued operations, held-for-sale or disposed of by sale
Current assets:
Receivables, net	571	479	304
Total current assets held for sale	571	479	304
Noncurrent assets:
Net property, plant and equipment	0	1,631	2,064
Deferred income taxes	1,711	2,637	62,163
Other	161	161	161
Total noncurrent assets held for sale	1,872	4,429	64,388
Total assets held for sale	2,443	4,908	64,692
Current liabilities:
Accounts payable	188	30	68
Taxes payable	7,463	10,857	11,745
Other accrued liabilities	1,948	2,884	2,380
Total current liabilities held for sale	9,599	13,771	14,193
Total liabilities held for sale	$ 9,599	$ 13,771	$ 14,193