Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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Income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
Income taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income taxes [Abstract]
Income tax provision	$ 581	$ 769	$ 1,064	$ 1,657
Effective tax rate	18.40%	29.80%	19.20%	31.40%
Total gross unrecognized tax benefits that would impact the effective rate	$ 76		$ 76
Previously unrecognized tax benefit recognized	28
Accrued interest and penalties related to uncertain tax positions	$ 14		$ 14
U.S. corporate income tax rate			21.00%		34.00%
Minimum [Member]
Income taxes [Abstract]
Effective tax rate			19.00%
Maximum [Member]
Income taxes [Abstract]
Effective tax rate			20.00%
U.S. corporate income tax rate					35.00%