CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities:
Net income	$ 85,002	$ 34,785
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	31,121	48,562
Equity compensation expense	13,147	10,317
Deferred income taxes	(1,267)	(9,987)
Equity in undistributed income of unconsolidated joint ventures	(5,884)	(3,177)
Dividends received from unconsolidated joint ventures	4,965	7,075
Pension settlement charges (benefits)	534	(63)
Pension and other postretirement benefits	(300)	(149)
(Gain) loss on sale or disposal of property, plant and equipment	(673)	49
Impairment charges	385	386
UTIS fire fixed asset and inventory write-offs	1,254	0
Provision (benefit) for credit losses	(310)	(63)
Changes in assets and liabilities:
Accounts receivable	(32,254)	(14,702)
Proceeds from insurance/government subsidies related to operations	264	0
Contract assets	(6,136)	394
Inventories	(19,386)	25,008
Pension and postretirement benefit contributions	(156)	(248)
Other current assets	(144)	1,876
Accounts payable and other accrued expenses	27,495	5,236
Other, net	8,458	8,374
Net cash provided by operating activities	106,115	113,673
Investing Activities:
Capital expenditures	(43,411)	(28,944)
Proceeds from the sale of property, plant and equipment, net	714	0
Net cash used in investing activities	(42,697)	(28,944)
Financing Activities:
Proceeds from borrowings under revolving credit facility	0	150,000
Repayment of debt principal and finance lease obligations	(29,655)	(213,299)
Payments of taxes related to net share settlement of equity awards	(2,752)	(5,107)
Proceeds from issuance of shares to employee stock purchase plan	1,563	1,373
Net cash (used in) provided by financing activities	(30,844)	(67,033)
Effect of exchange rate fluctuations on cash	(3,458)	1,578
Net increase in cash and cash equivalents	29,116	19,274
Cash and cash equivalents at beginning of period	191,785	166,849
Cash and cash equivalents at end of period	220,901	186,123
Supplemental Disclosures:
Accrued capital additions	6,447	1,493
Interest, net of amounts capitalized	1,285	4,301
Income taxes	$ 25,867	$ 21,645