Consolidated Statements of Equity - 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
Other comprehensive income (loss), net of related taxes:
Balance (in shares)	45,461
Balance (in shares) at Dec. 31, 2013	45,461
Balance at Dec. 31, 2013	$ 46	$ 735,295	$ (3,088)	$ 487	$ 732,740	$ 12,371	$ 745,111
Stock-based compensation		5,571			5,571		5,571
Exercise of options by employees and directors (in shares)	76
Exercise of options by employees and directors		981			981		981
Cash paid to non controlling interest						(651)	(651)
Cash dividend declared			(9,555)		(9,555)		(9,555)
Increase in noncontrolling interest in ORTP LLC						257	257
Acquisition of noncontrolling interest in Crump		159			159	(987)	(828)
Net income (loss)			54,182		54,182	833	55,015
Other comprehensive income (loss), net of related taxes:
Loss in respect of derivative instruments designated for cash flow hedge				(902)	(902)		(902)
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				(8,112)	(8,112)		(8,112)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(141)	(141)		(141)
Balance (in shares) at Dec. 31, 2014	45,537
Balance at Dec. 31, 2014	$ 46	742,006	41,539	(8,668)	774,923	11,823	786,746
Other comprehensive income (loss), net of related taxes:
Stock-based compensation		5,571			5,571		5,571
Exercise of options by employees and directors (in shares)	76
Exercise of options by employees and directors		981			981		981
Cash paid to non controlling interest						(651)	(651)
Cash dividend declared			(9,555)		(9,555)		(9,555)
Net income (loss)			54,182		54,182	833	55,015
Balance (in shares)	45,461
Increase in noncontrolling interest in ORTP LLC						257	257
Currency translation adjustments
Balance (in shares)	45,537
Stock-based compensation		3,955			3,955		3,955
Exercise of options by employees and directors (in shares)	574
Exercise of options by employees and directors		6,085			6,085		6,085
Cash paid to non controlling interest						(7,196)	(7,196)
Cash dividend declared			(12,716)		(12,716)		(12,716)
Net income (loss)			119,573		119,573	3,776	123,349
Loss in respect of derivative instruments designated for cash flow hedge				91	91		91
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				1,028	1,028		1,028
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(118)	(118)		(118)
Balance (in shares) at Dec. 31, 2015	49,107
Balance at Dec. 31, 2015	$ 49	849,223	148,396	(7,667)	990,001	93,873	1,083,874
Other comprehensive income (loss), net of related taxes:
Stock-based compensation		3,955			3,955		3,955
Exercise of options by employees and directors (in shares)	574
Exercise of options by employees and directors		6,085			6,085		6,085
Share exchange with Parent (Note 2) (in shares)	2,996
Share exchange with Parent (Note 2)	$ 3	26,012			26,015		26,015
Cash paid to non controlling interest						(7,196)	(7,196)
Cash dividend declared			(12,716)		(12,716)		(12,716)
Issuance of shares to noncontrolling interest, net of transaction costs		71,165			71,165	85,470	156,635
Net income (loss)			119,573		119,573	3,776	123,349
Balance (in shares)	45,537
Currency translation adjustments
Balance (in shares)	49,107
Stock-based compensation		5,157			5,157		5,157
Exercise of options by employees and directors (in shares)	560
Exercise of options by employees and directors	$ 1	7,249			7,250		7,250
Cash paid to non controlling interest						(57,391)	(57,391)
Cash dividend declared			(25,682)		(25,682)		(25,682)
Increase in noncontrolling interest in ORTP LLC						3,697	3,697
Net income (loss)			93,930		93,930	7,302	101,516
Loss in respect of derivative instruments designated for cash flow hedge				87	87		87
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				1,185	1,185		1,185
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(96)	(96)		(96)
Balance (in shares) at Dec. 31, 2016	49,667
Balance at Dec. 31, 2016	$ 50	869,463	216,644	(7,732)	1,078,425	91,582	1,170,007
Other comprehensive income (loss), net of related taxes:
Stock-based compensation		5,157			5,157		5,157
Exercise of options by employees and directors (in shares)	560
Exercise of options by employees and directors	$ 1	7,249			7,250		7,250
Cash paid to non controlling interest						(57,391)	(57,391)
Cash dividend declared			(25,682)		(25,682)		(25,682)
Issuance of shares to noncontrolling interest, net of transaction costs		7,834			7,834	36,268	44,102
Net income (loss)			93,930		93,930	7,302	101,516
Balance (in shares)	49,107
Increase in noncontrolling interest in Guadeloupe						8,240	8,240
Increase in noncontrolling interest in ORTP LLC						3,697	3,697
Currency translation adjustments				$ (1,241)	$ (1,241)	$ (407)	$ (1,648)
Balance (in shares)	49,667