Income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2017
Income taxes [Abstract]
Income tax provision	$ (465)	$ 115
Effective tax rate	31.90%	13.40%
Unrecognized tax benefits that would favorably affect effective income tax rate if recognized	$ 107
Unrecognized tax benefits that will lapse upon expiration of statute of limitations	27
Accrued interest and penalties related to uncertain tax positions	$ 21
U.S. corporate income tax rate			34.00%
Maximum [Member]
Income taxes [Abstract]
U.S. corporate income tax rate			35.00%