Consolidated Statements of Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2013	$ 46	$ 735,295	$ (3,088)	$ 487	$ 732,740	$ 12,371	$ 745,111
Balance (in Shares) at Dec. 31, 2013	45,461
Stock-based compensation		1,440			1,440		1,440
Exercise of options by employees and directors (in Shares)	18
Cash paid to noncontrolling interest						(140)	(140)
Cash dividend declared, per share			(2,727)		(2,727)		(2,727)
Other comprehensive income (loss), net of related taxes:
Increase in noncontrolling interest in ORTP LLC						257	257
Net income			21,552		21,552	237	21,789
Other comprehensive income (loss), net of related taxes:
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge (net of related tax)				(36)	(36)		(36)
Balance at Mar. 31, 2014	46	736,735	15,737	451	752,969	12,725	765,694
Balance (in Shares) at Mar. 31, 2014	45,479
Balance at Dec. 31, 2014	46	742,006	41,539	(8,668)	774,923	11,823	786,746
Balance (in Shares) at Dec. 31, 2014	45,537
Stock-based compensation		1,127			1,127		1,127
Exercise of options by employees and directors		2,704			2,704		2,704
Exercise of options by employees and directors (in Shares)	295
Share exchange with Parent (Note 1)	3	25,754			25,757		25,757
Share exchange with Parent (Note 1) (in Shares)	2,996
Cash paid to noncontrolling interest						(228)	(228)
Cash dividend declared, per share			(3,898)		(3,898)		(3,898)
Other comprehensive income (loss), net of related taxes:
Loss in respect of derivative instruments designated for cash flow hedge (net of related tax of $14)				23	23		23
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment (net of related tax of $0)				(3,296)	(3,296)		(3,296)
Net income			10,032		10,032	235	10,267
Other comprehensive income (loss), net of related taxes:
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge (net of related tax)				(30)	(30)		(30)
Balance at Mar. 31, 2015	$ 49	$ 771,591	$ 47,673	$ (11,971)	$ 807,342	$ 11,830	$ 819,172
Balance (in Shares) at Mar. 31, 2015	48,828