Income taxes (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2017
Income taxes [Abstract]
Income tax provision (benefit)	$ (687)		$ (921)	$ (1,243)	$ (1,386)
Effective tax rate	24.50%		33.20%	22.30%	32.80%
U.S. corporate income tax rate				21.00%		34.00%
Unrecognized tax benefits that would favorably affect effective income tax rate if recognized	$ 121			$ 121
Unrecognized tax benefits that will lapse upon expiration of statute of limitations		$ 24
Accrued interest and penalties related to uncertain tax positions	$ 25			$ 25

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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