Share Capital and Capital In Excess of Par Value (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 823,107
Balance at the beginning of the period (in shares)	102
Purchase and retirement of common shares and other		$ (1,604)
Purchase and retirement of common shares and other (in shares)	0	(37)
Balance at the end of the period	$ 834,106	$ 791,395
Balance at the end of the period (in shares)	105	102
Stock dividends (as a percent)	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)
Balance at the beginning of the period (in shares)	102	99
Issuance of 3% stock dividend (in shares)	3	3
Balance at the end of the period	$ (1,992)	$ (1,992)
Balance at the end of the period (in shares)	105	102
Capital in Excess of Par Value
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 737,453	$ 719,606
Issuance of 3% stock dividend	64,800	50,648
Purchase and retirement of common shares and other		(1,578)
Balance at the end of the period	802,253	768,676
Class B Common Stock | Common Stock.
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 20,448	$ 19,866
Balance at the beginning of the period (in shares)	29,445	28,607
Issuance of 3% stock dividend	$ 613	$ 596
Issuance of 3% stock dividend (in shares)	882	858
Conversion of Class B common shares to common shares	$ (12)	$ (2)
Conversion of Class B common shares to common shares (in shares)	(16)	(2)
Balance at the end of the period	$ 21,049	$ 20,460
Balance at the end of the period (in shares)	30,311	29,463
Common Stock | Common Stock.
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 27,777	$ 27,584
Balance at the beginning of the period (in shares)	39,999	39,721
Issuance of 3% stock dividend	$ 830	$ 823
Issuance of 3% stock dividend (in shares)	1,196	1,185
Conversion of Class B common shares to common shares	$ 12	$ 2
Conversion of Class B common shares to common shares (in shares)	16	2
Purchase and retirement of common shares and other		$ (26)
Purchase and retirement of common shares and other (in shares)		(37)
Balance at the end of the period	$ 28,619	$ 28,383
Balance at the end of the period (in shares)	41,211	40,871