Income taxes: Components of (loss) income before income taxes (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Components of income before income taxes
Domestic	$ 828	$ 14,113	$ 29,330	$ 31,902
Foreign	(2,899)	(2,814)	(5,199)	(7,770)
(Loss) income before income taxes	$ (2,071)	$ 11,299	$ 24,131	$ 24,132

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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