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		1,659			1,659		1,659
Exercise of options by employees and directors (in shares)	460
Exercise of options by employees and directors		5,945			5,945		5,945
Cash paid to non controlling interest						(5,752)	(5,752)
Cash dividend declared			(18,998)		(18,998)		(18,998)
Net income			53,425		53,425	2,258	55,683
Loss in respect of derivative instruments designated for cash flow hedge for the six months ended June 30, 2017				70	70		70
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				(5,166)	(5,166)		(5,166)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(48)	(48)		(48)
Balances (in shares) at Jun. 30, 2016	49,567
Balances at Jun. 30, 2016	$ 49	856,827	186,753	(13,308)	1,030,321	90,379	1,120,700
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		5,343			5,343		5,343
Exercise of options by employees and directors (in shares)	243
Exercise of options by employees and directors		785			785		785
Cash paid to non controlling interest						(14,594)	(14,594)
Cash dividend declared			(12,426)		(12,426)		(12,426)
Net income			43,834		43,834	6,941	50,775
Loss in respect of derivative instruments designated for cash flow hedge for the six months ended June 30, 2017				93	93		93
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				(347)	(347)		(347)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(39)	(39)		(39)
Balances (in shares) at Jun. 30, 2017	49,910
Balances at Jun. 30, 2017	$ 50	875,591	246,760	(7,325)	1,115,076	84,325	1,199,401
Currency translation adjustment				$ 1,143	$ 1,143	$ 396	$ 1,539