SHARE CAPITAL AND CAPITAL IN EXCESS OF PAR VALUE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 782,882
Balance at the beginning of the period (in shares)	99
Balance at the end of the period	$ 823,107	$ 782,882
Balance at the end of the period (in shares)	102	99
Total Number of Shares Purchased	928	818	921
Average Price Paid Per Share (in dollars per share)	$ 35.66	$ 38.98	$ 32.76
Stock dividends (as a percent)	3.00%	3.00%	3.00%
Common Stock.
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 27,584	$ 27,322	$ 27,134
Balance at the beginning of the period (in shares)	39,721	39,344	39,073
Issuance of 3% stock dividend	$ 823	$ 817	$ 807
Issuance of 3% stock dividend (in shares)	1,185	1,176	1,163
Conversion of Class B common shares to common shares	$ 14	$ 13	$ 20
Conversion of Class B common shares to common shares (in shares)	20	19	29
Purchase and retirement of common shares and other	$ (644)	$ (568)	$ (639)
Purchase and retirement of common shares and other (in shares)	(927)	(818)	(921)
Balance at the end of the period	$ 27,777	$ 27,584	$ 27,322
Balance at the end of the period (in shares)	39,999	39,721	39,344
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)
Balance at the beginning of the period (in shares)	99	96	93
Issuance of 3% stock dividend (in shares)	3	3	3
Balance at the end of the period	$ (1,992)	$ (1,992)	$ (1,992)
Balance at the end of the period (in shares)	102	99	96
Capital in Excess of Par Value
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 719,606	$ 709,880	$ 706,930
Issuance of 3% stock dividend	50,649	41,068	32,495
Purchase and retirement of common shares and other	(32,802)	(31,342)	(29,545)
Balance at the end of the period	737,453	719,606	709,880
Class B Common Stock | Common Stock.
Changes in share capital and capital in excess of par value
Balance at the beginning of the period	$ 19,866	$ 19,300	$ 18,758
Balance at the beginning of the period (in shares)	28,607	27,793	27,012
Issuance of 3% stock dividend	$ 596	$ 579	$ 562
Issuance of 3% stock dividend (in shares)	858	833	810
Conversion of Class B common shares to common shares	$ (14)	$ (13)	$ (20)
Conversion of Class B common shares to common shares (in shares)	(20)	(19)	(29)
Balance at the end of the period	$ 20,448	$ 19,866	$ 19,300
Balance at the end of the period (in shares)	29,445	28,607	27,793