Income taxes: Components of (loss) income before income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of income before income taxes
Domestic	$ 73,753	$ 23,808	$ 72,773
Foreign	(2,333)	(13,496)	(20,099)
Total income before income taxes	$ 71,420	$ 10,312	$ 52,674