Share Capital and Capital In Excess of Par Value (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Changes in share capital and capital in excess of par value
Balance at the beginning of the period			$ 940,568
Balance at the beginning of the period (in shares)			108
Purchase and retirement of common shares			$ (3,822)	$ (6,483)
Purchase and retirement of common shares (in shares)			(100)	(209)
Balance at the end of the period	$ 951,808	$ 892,762	$ 951,808	$ 892,762
Balance at the end of the period (in shares)	111	108	111	108
Stock dividends (as a percent)	3.00%	3.00%	3.00%	3.00%
Treasury Stock
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ (1,991)	$ (1,992)	$ (1,991)	$ (1,992)
Balance at the beginning of the period (in shares)	111	108	108	105
Issuance of 3% stock dividend (in shares)			3	3
Balance at the end of the period	$ (1,991)	$ (1,992)	$ (1,991)	$ (1,992)
Balance at the end of the period (in shares)	111	108	111	108
Capital in Excess of Par Value
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 918,794	$ 847,308	$ 847,308	$ 788,894
Issuance of 3% stock dividend			71,486	64,816
Purchase and retirement of common shares	(3,792)		(3,792)	(6,402)
Balance at the end of the period	915,002	847,308	915,002	847,308
Common Stock | Common Stock
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 29,911	$ 29,025	$ 29,042	$ 28,325
Balance at the beginning of the period (in shares)	43,073	41,796	41,821	40,789
Issuance of 3% stock dividend			$ 868	$ 842
Issuance of 3% stock dividend (in shares)			1,250	1,213
Conversion of Class B common shares to common shares	$ 6	$ 8	$ 7	$ 10
Conversion of Class B common shares to common shares (in shares)	8	12	10	15
Purchase and retirement of common shares	$ (69)		$ (69)	$ (144)
Purchase and retirement of common shares (in shares)	(100)		(100)	(209)
Balance at the end of the period	$ 29,848	$ 29,033	$ 29,848	$ 29,033
Balance at the end of the period (in shares)	42,981	41,808	42,981	41,808
Class B Common Stock | Common Stock
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 22,290	$ 21,660	$ 21,643	$ 21,032
Balance at the beginning of the period (in shares)	32,098	31,191	31,166	30,286
Issuance of 3% stock dividend	$ 1		$ 649	$ 630
Issuance of 3% stock dividend (in shares)			934	908
Conversion of Class B common shares to common shares	$ (6)	$ (8)	$ (7)	$ (10)
Conversion of Class B common shares to common shares (in shares)	(8)	(12)	(10)	(15)
Balance at the end of the period	$ 22,285	$ 21,652	$ 22,285	$ 21,652
Balance at the end of the period (in shares)	32,090	31,179	32,090	31,179