Share Capital and Capital In Excess of Par Value (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Changes in share capital and capital in excess of par value
Balance at the beginning of the period			$ 870,409
Balance at the beginning of the period (in shares)			105
Purchase and retirement of common shares and other			$ (6,483)	$ (2,196)
Purchase and retirement of common shares and other (in shares)			(209)	(77)
Balance at the end of the period	$ 918,473	$ 869,830	$ 918,473	$ 869,830
Balance at the end of the period (in shares)	108	105	108	105
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	$ (1,992)	$ (1,992)	$ (1,992)	$ (1,992)
Balance at the beginning of the period (in shares)	108	105	105	102
Issuance of 3% stock dividend (in shares)			3	3
Balance at the end of the period	$ (1,992)	$ (1,992)	$ (1,992)	$ (1,992)
Balance at the end of the period (in shares)	108	105	108	105
Capital in Excess of Par Value
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 847,308	$ 802,253	$ 788,894	$ 737,453
Issuance of 3% stock dividend			64,816	64,800
Purchase and retirement of common shares and other		(2,166)	(6,402)	(2,166)
Balance at the end of the period	847,308	800,087	847,308	800,087
Common Stock | Common Stock
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 29,033	$ 28,620	$ 28,325	$ 27,777
Balance at the beginning of the period (in shares)	41,808	41,213	40,789	39,999
Issuance of 3% stock dividend			$ 842	$ 830
Issuance of 3% stock dividend (in shares)			1,213	1,196
Conversion of Class B common shares to common shares	$ 9	$ 7	$ 19	$ 20
Conversion of Class B common shares to common shares (in shares)	13	10	28	28
Purchase and retirement of common shares and other		$ (53)	$ (144)	$ (53)
Purchase and retirement of common shares and other (in shares)		(77)	(209)	(77)
Balance at the end of the period	$ 29,042	$ 28,574	$ 29,042	$ 28,574
Balance at the end of the period (in shares)	41,821	41,146	41,821	41,146
Class B Common Stock | Common Stock
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 21,652	$ 21,048	$ 21,032	$ 20,448
Balance at the beginning of the period (in shares)	31,179	30,309	30,286	29,445
Issuance of 3% stock dividend			$ 630	$ 613
Issuance of 3% stock dividend (in shares)			908	882
Conversion of Class B common shares to common shares	$ (9)	$ (7)	$ (19)	$ (20)
Conversion of Class B common shares to common shares (in shares)	(13)	(10)	(28)	(28)
Balance at the end of the period	$ 21,643	$ 21,041	$ 21,643	$ 21,041
Balance at the end of the period (in shares)	31,166	30,299	31,166	30,299