CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net income (loss)	$ 8,025	$ (8,965)
Adjustments to reconcile net income or loss to net cash provided by operating activities:
Depreciation and amortization	24,744	23,370
Amortization of premium from senior unsecured bonds	(78)
Accretion of asset retirement obligation	413	387
Stock-based compensation	1,657	1,727
Amortization of deferred lease income	(671)	(671)
Income attributable to sale of tax benefits, net of interest expense	(869)	(542)
Equity in losses of investees	140	412
Impairment of auction rate securities		207
Write-off of unsuccessful exploration activities	768
Loss on severance pay fund asset	(641)	(614)
Premium from issuance senior unsecured bonds		1,975
Deferred income tax provision	4,460	145
Liability for unrecognized tax benefits	534	(1,137)
Deferred lease revenues	37	(269)
Changes in operating assets and liabilities, net of amounts acquired:
Receivables	9,086	(14,367)
Costs and estimated earnings in excess of billings on uncompleted contracts	(4,652)	2,615
Inventories	(4,659)	(2,016)
Prepaid expenses and other	(1,191)	1,138
Deposits and other	(169)	(132)
Accounts payable and accrued expenses	4,877	(3,184)
Due from/to related entities, net	(20)	(29)
Billings in excess of costs and estimated earnings on uncompleted contracts	(949)	12,223
Liabilities for severance pay	1,127	1,281
Other long-term liabilities	(232)	(257)
Due from/to Parent	137	(231)
Net cash provided by operating activities	41,874	13,066
Cash flows from investing activities:
Marketable securities, net	2,772	(22,965)
Net change in restricted cash, cash equivalents and marketable securities	376	(29,920)
Capital expenditures	(65,430)	(55,052)
Investment in unconsolidated companies	(115)
Increase in severance pay fund asset, net of payments made to retired employees	64	13
Net cash used in investing activities	(62,333)	(107,924)
Cash flows from financing activities:
Proceeds from issuance of senior unsecured bonds		107,447
Proceeds from the sale of limited liability company interest in OPC LLC		24,878
Proceeds from revolving credit lines with banks	182,641	79,334
Repayment of revolving credit lines with banks	(169,048)	(150,300)
Repayments of long-term debt	(3,845)	(2,434)
Cash paid to non-controlling interest	(4,229)	(2,616)
Deferred debt issuance costs	(366)	(1,301)
Cash dividends paid		(2,290)
Net cash provided by financing activities	5,153	52,718
Net change in cash and cash equivalents	(15,306)	(42,140)
Cash and cash equivalents at beginning of period	99,886	82,815
Cash and cash equivalents at end of period	84,580	40,675
Supplemental non-cash investing and financing activities:
Decrease in accounts payable related to purchases of property, plant and equipment	(11,509)	(5,947)
Accrued liabilities related to financing activities	$ 513	$ 325