Condensed Consolidated Statements of Cash Flow (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 33,024	$ 55,176
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	85,539	74,859
Accretion of asset retirement obligation	1,911	1,545
Stock-based compensation	4,720	4,253
Income attributable to sale of tax benefits, net of interest expense	(9,408)	(5,538)
Equity in earnings of investees	(1,147)	(923)
Mark-to-market of derivative instruments	1,096	(2,043)
Loss on disposal of property, plant and equipment	81	801
Loss (gain) on severance pay fund asset	105	38
Deferred income tax provision	(4,528)	19,731
Liability for unrecognized tax benefits	1,494	666
Changes in operating assets and liabilities, net of businesses acquired:
Receivables	9,926	(24,831)
Costs and estimated earnings in excess of billings on uncompleted contracts	10,707	18,888
Inventories	6,795	(3,983)
Prepaid expenses and other	(4,866)	1,719
Change in operating lease right of use asset	1,422	1,865
Deposits and other	(319)	1,048
Accounts payable and accrued expenses	(37,714)	10,009
Billings in excess of costs and estimated earnings on uncompleted contracts	2,273	2,844
Liabilities for severance pay	(1,058)	84
Change in operating lease liabilities	(1,153)	(1,634)
Other long-term liabilities	(56)	(220)
Net cash provided by operating activities	98,844	154,354
Cash flows from investing activities:
Purchase of marketable securities	(47,621)	0
Maturities of marketable securities	1,650	0
Capital expenditures	(207,888)	(151,254)
Investment in unconsolidated companies	(2,005)	(7,759)
Decrease (increase) in severance pay fund asset, net of payments made to retired employees	1,352	(14)
Net cash used in investing activities	(254,512)	(159,027)
Cash flows from financing activities:
Proceeds from long-term loans, net of transaction costs	0	129,407
Repayments of commercial paper and prepayment of loans	0	(46,225)
Proceeds from revolving credit lines with banks	0	1,250,639
Repayment of revolving credit lines with banks	0	(1,191,132)
Cash received from noncontrolling interest	5,390	7,577
Repayments of long-term debt	(36,481)	(31,784)
Stock issuance costs reimbursement	285	0
Cash paid to noncontrolling interest	(5,214)	(3,661)
Payments under finance lease obligations	(1,558)	(1,389)
Deferred debt issuance costs	(232)	(677)
Cash dividends paid	(13,166)	(11,333)
Net cash provided by (used in) financing activities	(50,976)	101,422
Effect of exchange rate changes	(257)	(25)
Net change in cash and cash equivalents and restricted cash and cash equivalents	(206,901)	96,724
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period	536,778	153,110
Cash and cash equivalents and restricted cash and cash equivalents at end of period	329,877	249,834
Supplemental non-cash investing and financing activities:
Increase (decrease) in accounts payable related to purchases of property, plant and equipment	(4,499)	(2,226)
Right of use assets obtained in exchange for new lease liabilities	$ 4,673	$ 2,135