Interim Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Dec. 31, 2019	15,332,206
Balance at Dec. 31, 2019	$ 153	$ 222,787	$ 553,093	$ 2,560	$ 476	$ 779,069
Net income			(26,852)		36	(26,816)
Other comprehensive income (loss)				(2,012)		(2,012)
Stock–based compensation		466				466
Shares sold – options exercised (in shares)	15,006
Shares sold – options exercised	$ 0	400				400
Repurchase of common shares (in shares)	(611)
Repurchase of common shares		(53)				(53)
Dividends declared to common stockholders ($0.52 per share)			(7,980)			(7,980)
Contributions attributable to noncontrolling interest					281	281
Balance (in shares) at Mar. 31, 2020	15,346,601
Balance at Mar. 31, 2020	$ 153	223,600	518,261	548	793	743,355
Balance (in shares) at Dec. 31, 2019	15,332,206
Balance at Dec. 31, 2019	$ 153	222,787	553,093	2,560	476	779,069
Net income						14,574
Other comprehensive income (loss)						2,171
Balance (in shares) at Sep. 30, 2020	15,359,488
Balance at Sep. 30, 2020	$ 153	225,616	543,460	4,731	3,217	777,177
Balance (in shares) at Dec. 31, 2019	15,332,206
Balance at Dec. 31, 2019	$ 153	222,787	553,093	2,560	476	$ 779,069
Shares sold – options exercised (in shares)						43,630
Balance (in shares) at Dec. 31, 2020	15,369,745
Balance at Dec. 31, 2020	$ 153	226,943	563,024	5,057	3,083	$ 798,260
Balance (in shares) at Mar. 31, 2020	15,346,601
Balance at Mar. 31, 2020	$ 153	223,600	518,261	548	793	743,355
Net income			28,324		198	28,522
Other comprehensive income (loss)				3,780		3,780
Stock–based compensation		823				823
Shares sold – options exercised (in shares)	11,073
Shares sold – options exercised		549				549
Repurchase of common shares (in shares)	(186)
Dividends declared to common stockholders ($0.52 per share)			(7,986)			(7,986)
Contributions attributable to noncontrolling interest					244	244
Balance (in shares) at Jun. 30, 2020	15,357,488
Balance at Jun. 30, 2020	$ 153	224,972	538,599	4,328	1,235	769,287
Net income	0	0	12,849	0	19	12,868
Other comprehensive income (loss)	0	0	0	403	0	403
Stock–based compensation	$ 0	518	0	0	0	518
Shares sold – options exercised (in shares)	2,000
Shares sold – options exercised	$ 0	126	0	0	0	126
Dividends declared to common stockholders ($0.52 per share)	0	0	(7,988)	0	0	(7,988)
Contributions attributable to noncontrolling interest	$ 0	0	0	0	1,963	1,963
Balance (in shares) at Sep. 30, 2020	15,359,488
Balance at Sep. 30, 2020	$ 153	225,616	543,460	4,731	3,217	777,177
Balance (in shares) at Dec. 31, 2020	15,369,745
Balance at Dec. 31, 2020	$ 153	226,943	563,024	5,057	3,083	798,260
Net income			21,267		41	21,308
Other comprehensive income (loss)				(1,922)		(1,922)
Stock–based compensation		496				496
Shares sold – options exercised (in shares)	24,331
Shares sold – options exercised	$ 1	326				327
Repurchase of common shares (in shares)	(3,936)
Repurchase of common shares		(278)				(278)
Dividends declared to common stockholders ($0.52 per share)			(8,003)			(8,003)
Balance (in shares) at Mar. 31, 2021	15,390,140
Balance at Mar. 31, 2021	$ 154	227,487	576,288	3,135	3,124	810,188
Balance (in shares) at Dec. 31, 2020	15,369,745
Balance at Dec. 31, 2020	$ 153	226,943	563,024	5,057	3,083	798,260
Net income						123,092
Other comprehensive income (loss)						$ (2,291)
Shares sold – options exercised (in shares)						148,900
Balance (in shares) at Sep. 30, 2021	15,423,240
Balance at Sep. 30, 2021	$ 154	230,974	661,783	2,766	6,213	$ 901,890
Balance (in shares) at Mar. 31, 2021	15,390,140
Balance at Mar. 31, 2021	$ 154	227,487	576,288	3,135	3,124	810,188
Net income			104,883		447	105,330
Other comprehensive income (loss)				153		153
Stock–based compensation		683				683
Shares sold – options exercised (in shares)	33,100
Shares sold – options exercised		2,078				2,078
Dividends declared to common stockholders ($0.52 per share)			(8,020)			(8,020)
Contributions attributable to noncontrolling interest					2,840	2,840
Balance (in shares) at Jun. 30, 2021	15,423,240
Balance at Jun. 30, 2021	$ 154	230,248	673,151	3,288	6,411	913,252
Net income	0	0	(3,348)	0	(198)	(3,546)
Other comprehensive income (loss)	0	0	0	(522)	0	(522)
Stock–based compensation	0	726	0	0	0	726
Dividends declared to common stockholders ($0.52 per share)	$ 0	0	(8,020)	0	0	(8,020)
Balance (in shares) at Sep. 30, 2021	15,423,240
Balance at Sep. 30, 2021	$ 154	$ 230,974	$ 661,783	$ 2,766	$ 6,213	$ 901,890