Stock option and award plan: Incentive award plan, additional information (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Incentive Award Plan, additional information
Equity-based compensation expense	$ 26,417	$ 25,738	$ 26,924
Total unrecognized compensation cost	$ 60,600
Weighted-average period to recognize unrecognized compensation cost	2 years 3 months 18 days
Restricted stock
Incentive Award Plan, additional information
Equity-based compensation expense	$ 26,417	25,738	26,924
Income tax benefit related to stock options and restricted stock	2,412	2,469	3,307
Capitalized compensation expense related to stock options and restricted stock	3,521	3,100	3,541
Intrinsic value of stock options exercised	52	573	456
Fair value of shares of restricted stock vested	$ 25,525	$ 22,489	$ 30,113

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479983/718-10-S45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479830/718-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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