Income taxes: The components of income before income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
The components of income before income taxes
Domestic	$ 1,112,947	$ 22,984	$ 1,115,925	$ 26,335
Foreign	(13,415)	(3,266)	(5,741)	(4,939)
Total	$ 1,099,532	$ 19,718	$ 1,110,184	$ 21,396