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
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
Stock-based compensation		842			842		842
Exercise of options by employees and directors (in shares)	213
Exercise of options by employees and directors		4,195			4,195		4,195
Cash paid to non controlling interest						(2,869)	(2,869)
Cash dividend declared			(15,472)		(15,472)		(15,472)
Net income			29,271		29,271	1,674	30,945
Other comprehensive income (loss), net of related taxes:
Loss in respect of derivative instruments designated for cash flow hedge				21	21		21
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				(3,179)	(3,179)		(3,179)
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(24)	(24)		(24)
Balance (in shares) at Mar. 31, 2016	49,320
Balance at Mar. 31, 2016	$ 49	854,260	162,195	(10,849)	1,005,655	92,678	1,098,333
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		842			842		842
Exercise of options by employees and directors (in shares)	213
Exercise of options by employees and directors		4,195			4,195		4,195
Cash paid to non controlling interest						(2,869)	(2,869)
Cash dividend declared			(15,472)		(15,472)		(15,472)
Net income			29,271		29,271	1,674	30,945
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
Stock-based compensation		1,713			1,713		1,713
Exercise of options by employees and directors (in shares)	39
Exercise of options by employees and directors
Cash paid to non controlling interest						(6,807)	(6,807)
Cash dividend declared			(8,448)		(8,448)		(8,448)
Net income			35,312		35,312	4,079	39,735
Other comprehensive income (loss), net of related taxes:
Loss in respect of derivative instruments designated for cash flow hedge				22	22		22
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment				569	569		569
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge				(24)	(24)		(24)
Balance (in shares) at Mar. 31, 2017	49,706
Balance at Mar. 31, 2017	$ 50	871,176	243,508	(7,076)	1,107,658	88,843	1,196,501
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		1,713			1,713		1,713
Exercise of options by employees and directors (in shares)	39
Exercise of options by employees and directors
Cash paid to non controlling interest						(6,807)	(6,807)
Cash dividend declared			(8,448)		(8,448)		(8,448)
Net income			35,312		35,312	4,079	39,735
Currency translation adjustment				$ 89	$ 89	$ (11)	$ 78