Condensed Consolidated Statements of Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] AOCI Attributable to Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Noncontrolling Interest [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] AOCI Attributable to Parent [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Parent [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Noncontrolling Interest [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Dec. 31, 2018	50,700														50,700
Balance at Dec. 31, 2018	$ 0	$ 0	$ (58)	$ 0	$ (58)	$ 0	$ (58)	$ 51	$ 901,363	$ 422,164	$ (3,799)	$ 1,319,779	$ 125,259	$ 1,445,038	$ 51	$ 901,363	$ 422,222	$ (3,799)	$ 1,319,837	$ 125,259	$ 1,445,096
Stock-based compensation															$ 0	2,360	0	0	2,360	0	2,360
Exercise of options by employees and directors (in shares)															52
Exercise of options by employees and directors															$ 0	0	0	0	0	0	0
Cash paid to noncontrolling interest															0	0	0	0	0	(4,146)	(4,146)
Cash dividend declared															0	0	(5,579)	0	(5,579)	0	(5,579)
Net income															0	0	25,946	0	25,946	1,855	27,801
Change in foreign currency translation adjustments															0	0	0	(1,026)	(1,026)	(322)	(1,348)
Change in respect of derivative instruments designated for cash flow hedge															0	0	0	22	22	0	22
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment															0	0	0	(1,145)	(1,145)	0	(1,145)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge															$ 0	0	0	(8)	(8)	0	(8)
Balance (in shares) at Mar. 31, 2019															50,752
Balance at Mar. 31, 2019															$ 51	903,723	442,531	(5,956)	1,340,349	122,646	1,462,995
Balance (in shares) at Dec. 31, 2018	50,700														50,700
Balance at Dec. 31, 2018	$ 0	0	(58)	0	(58)	0	(58)	51	901,363	422,164	(3,799)	1,319,779	125,259	1,445,038	$ 51	901,363	422,222	(3,799)	1,319,837	125,259	1,445,096
Change in foreign currency translation adjustments																					(866)
Balance (in shares) at Jun. 30, 2019															50,862
Balance at Jun. 30, 2019															$ 51	906,366	470,880	(7,736)	1,369,561	122,080	1,491,641
Balance (in shares) at Mar. 31, 2019															50,752
Balance at Mar. 31, 2019															$ 51	903,723	442,531	(5,956)	1,340,349	122,646	1,462,995
Stock-based compensation															$ 0	2,643	0	0	2,643	0	2,643
Exercise of options by employees and directors (in shares)															110
Exercise of options by employees and directors															$ 0	0	0	0	0	0	0
Cash paid to noncontrolling interest															0	0	0	0	0	(2,767)	(2,767)
Cash dividend declared															0	0	(5,589)	0	(5,589)	0	(5,589)
Net income															0	0	33,938	0	33,938	2,017	35,955
Change in foreign currency translation adjustments															0	0	0	298	298	184	482
Change in respect of derivative instruments designated for cash flow hedge															0	0	0	18	18	0	18
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment															0	0	0	(2,087)	(2,087)	0	(2,087)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge															$ 0	0	0	(9)	(9)	0	(9)
Balance (in shares) at Jun. 30, 2019															50,862
Balance at Jun. 30, 2019															$ 51	906,366	470,880	(7,736)	1,369,561	122,080	1,491,641
Balance (in shares) at Dec. 31, 2019	51,032														51,032
Balance at Dec. 31, 2019	$ 0	0	(755)	0	(755)	0	(755)	51	913,150	487,118	(8,654)	1,391,665	122,990	1,514,655	$ 51	913,150	487,873	(8,654)	1,392,420	122,990	1,515,410
Stock-based compensation															$ 0	1,989	0	0	1,989	0	1,989
Exercise of options by employees and directors (in shares)															4
Exercise of options by employees and directors															$ 0	0	0	0	0	0	0
Cash paid to noncontrolling interest															0	0	0	0	0	(3,007)	(3,007)
Cash dividend declared															0	0	(5,614)	0	(5,614)	0	(5,614)
Net income															0	0	26,033	0	26,033	3,543	29,576
Change in foreign currency translation adjustments															0	0	0	(258)	(258)	(387)	(645)
Change in respect of derivative instruments designated for cash flow hedge															0	0	0	13	13	0	13
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment															0	0	0	(4,755)	(4,755)	0	(4,755)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge															0	0	0	(8)	(8)	0	(8)
Increase in noncontrolling interest															$ 0	0	0	0	0	1,447	1,447
Balance (in shares) at Mar. 31, 2020															51,036
Balance at Mar. 31, 2020															$ 51	915,139	507,537	(13,662)	1,409,065	124,586	1,533,651
Balance (in shares) at Dec. 31, 2019	51,032														51,032
Balance at Dec. 31, 2019	$ 0	$ 0	$ (755)	$ 0	$ (755)	$ 0	$ (755)	$ 51	$ 913,150	$ 487,118	$ (8,654)	$ 1,391,665	$ 122,990	$ 1,514,655	$ 51	913,150	487,873	(8,654)	1,392,420	122,990	1,515,410
Change in foreign currency translation adjustments																					276
Balance (in shares) at Jun. 30, 2020															51,067
Balance at Jun. 30, 2020															$ 51	917,403	524,864	(13,921)	1,428,397	128,414	1,556,811
Balance (in shares) at Mar. 31, 2020															51,036
Balance at Mar. 31, 2020															$ 51	915,139	507,537	(13,662)	1,409,065	124,586	1,533,651
Stock-based compensation															$ 0	2,264	0	0	2,264	0	2,264
Exercise of options by employees and directors (in shares)															31
Exercise of options by employees and directors															$ 0	0	0	0	0	0	0
Cash dividend declared															0	0	(5,719)	0	(5,719)	0	(5,719)
Net income															0	0	23,046	0	23,046	1,982	25,028
Change in foreign currency translation adjustments															0	0	0	382	382	539	921
Change in respect of derivative instruments designated for cash flow hedge															0	0	0	17	17	0	17
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment															0	0	0	(653)	(653)	0	(653)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge															0	0	0	(5)	(5)	0	(5)
Increase in noncontrolling interest															$ 0	0	0	0	0	1,307	1,307
Balance (in shares) at Jun. 30, 2020															51,067
Balance at Jun. 30, 2020															$ 51	$ 917,403	$ 524,864	$ (13,921)	$ 1,428,397	$ 128,414	$ 1,556,811