CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 60,654	$ 19,361
Non-cash items included in net income:
Depreciation and amortization	49,685	48,929
Impairment loss		32,311
Stock-based compensation charges	11,838	9,242
Loss from investments in Unconsolidated Affiliates	8,054	4,351
Other non-cash items	12,375	4,948
Changes in operating assets and liabilities that provided (used) cash:
Accounts receivable	37,453	(30,835)
Contracts in progress, net of Advance billings on contracts	(410,678)	67,698
Accounts payable	260,091	(65,212)
Accrued and other current liabilities	68,722	(45,523)
Other assets and liabilities, net	(8,011)	30,520
Total cash provided by operating activities	90,183	75,790
Cash flows from investing activities:
Purchases of property, plant and equipment	(80,922)	(170,674)
Proceeds from asset dispositions	55,391	388
Investments in Unconsolidated Affiliates	(1,300)	(4,105)
Total cash used in investing activities	(26,831)	(174,391)
Cash flows from financing activities:
Repayment of debt	(230,509)	(88,845)
Payment of debt and letter of credit issuance cost	(18,784)	(8,211)
Acquisition of NCI	(10,652)
Repurchase of common stock	(7,020)	(2,572)
Total cash used in financing activities	(266,965)	(99,628)
Effects of exchange rate changes on cash, cash equivalents and restricted cash	160	(601)
Net decrease in cash, cash equivalents and restricted cash	(203,453)	(198,830)
Cash, cash equivalents and restricted cash at beginning of period	612,333	781,645
Cash, cash equivalents and restricted cash at end of period	$ 408,880	$ 582,815