Description of the business and recent developments: Stockholders' deficit (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Increase (Decrease) in Stockholders' Equity
Balance	$ (408,606)	$ (307,559)	$ (373,098)	$ (293,166)
Balance (in shares)			47,674,189
Equity-based compensation	6,479	8,476	$ 13,093	16,307
Foreign currency translation	(7,493)	1,776	(9,658)	(3,434)
Issuances of common stock				1
Exercises of options	130	660	334	875
Dividends paid	(41,855)	(37,001)	(83,153)	(73,082)
Net income (loss)	11,164	(2,493)	12,301	16,358
Balance	$ (440,181)	(336,141)	$ (440,181)	(336,141)
Balance (in shares)	48,003,724		48,003,724
Common Stock
Increase (Decrease) in Stockholders' Equity
Balance	$ 48	$ 48	$ 48	$ 47
Balance (in shares)	47,926,580	47,522,672	47,674,189	47,214,077
Forfeitures of shares granted to employees (in shares)	(42,783)	(5,626)	(52,365)	(25,302)
Issuances of common stock				$ 1
Issuances of common stock (in shares)	116,480	125,060	373,280	448,760
Exercises of options (in shares)	3,447	13,025	8,620	17,596
Balance	$ 48	$ 48	$ 48	$ 48
Balance (in shares)	48,003,724	47,655,131	48,003,724	47,655,131
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity
Balance	$ 554,552	$ 523,913	$ 547,734	$ 515,867
Equity-based compensation	6,479	8,476	13,093	16,307
Exercises of options	130	660	334	875
Balance	561,161	533,049	561,161	533,049
Accumulated Other Comprehensive Income
Increase (Decrease) in Stockholders' Equity
Balance	(13,168)	(6,516)	(11,003)	(1,306)
Foreign currency translation	(7,493)	1,776	(9,658)	(3,434)
Balance	(20,661)	(4,740)	(20,661)	(4,740)
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity
Balance	(950,038)	(825,004)	(909,877)	(807,774)
Dividends paid	(41,855)	(37,001)	(83,153)	(73,082)
Net income (loss)	11,164	(2,493)	12,301	16,358
Balance	$ (980,729)	$ (864,498)	$ (980,729)	$ (864,498)