Reconciliation of income and expenses (Details 5) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations	$ 477	$ 1,687	[1]
Discontinued operations, held-for-sale or disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	66	105
Operating expenses	174	(6,577)
Operating income (loss)	(108)	6,682
Other income	12
Other expense		(15)
Interest expense	575	0
Income (loss) from discontinued operations before income taxes	(671)	6,667
Income taxes	(1,148)	4,980	[2]
Income from discontinued operations	$ 477	$ 1,687

[1] Includes an elimination for the presentation of income tax adjustments between continuing and discontinued operations.

[2] Includes an elimination for the presentation of income tax adjustments between continuing and discontinued operations.