Consolidated Statements of Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balances (in shares) at Dec. 31, 2015	49,107
Balances at Dec. 31, 2015	$ 49	$ 849,223	$ 152,326	$ (8,164)	$ 993,434	$ 93,873	$ 1,087,307
Stock-based compensation		3,383			3,383		3,383
Exercise of options by employees and directors (in shares)	528
Exercise of options by employees and directors	$ 1	7,249			7,250		7,250
Cash paid to noncontrolling interest						(10,622)	(10,622)
Cash dividend declared			(22,469)		(22,469)		(22,469)
Increase in noncontrolling interest in Guadeloupe						8,272	8,272
Net income			65,384		65,384	4,390	69,774
Loss in respect of derivative instruments designated for cash flow hedge				105	105		105
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				(3,829)	(3,829)		(3,829)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(72)	(72)		(72)
Balances (in shares) at Sep. 30, 2016	49,635
Balances at Sep. 30, 2016	$ 50	859,855	195,241	(11,960)	1,043,186	95,913	1,139,099
Currency translation adjustment
Balances (in shares) at Dec. 31, 2016	49,667
Balances at Dec. 31, 2016	$ 50	869,463	215,352	(8,175)	1,076,690	91,582	1,168,272
Stock-based compensation		7,204			7,204		7,204
Exercise of options by employees and directors (in shares)	930
Exercise of options by employees and directors	$ 1	16,382			16,383		16,383
Cash paid to noncontrolling interest						(18,032)	(18,032)
Cash dividend declared			(16,612)		(16,612)		(16,612)
Net income			67,794		67,794	10,154	77,948
Loss in respect of derivative instruments designated for cash flow hedge				113	113		113
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				271	271		271
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(57)	(57)		(57)
Balances (in shares) at Sep. 30, 2017	50,597
Balances at Sep. 30, 2017	$ 51	896,005	266,534	(6,026)	1,156,564	77,462	1,234,026
Buyout of Class B membership in ORTP		2,956			2,956	(6,964)	(4,008)
Currency translation adjustment				$ 1,822	$ 1,822	$ 722	$ 2,544