CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating Activities:
Net income	$ 27,779	$ 52,692
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	25,858	25,099
Equity compensation expense	7,022	6,143
Deferred income taxes	(8,976)	(2,536)
Equity in undistributed income of unconsolidated joint ventures	(2,240)	(2,579)
Dividends received from unconsolidated joint ventures	1,785	1,741
Pension settlement benefits	(63)	0
Pension and other postretirement benefits	(100)	(346)
Asbestos-related charges	0	67
Loss on sale or disposal of property, plant and equipment	53	276
Impairment charges	0	956
Provision (benefit) for doubtful accounts	54	(128)
Changes in assets and liabilities:
Accounts receivable	(6,623)	(12,747)
Contract assets	3,174	(2,845)
Inventories	7,910	(2,845)
Pension and postretirement benefit contributions	(244)	(11)
Other current assets	414	(1,211)
Accounts payable and other accrued expenses	(6,129)	3,653
Other, net	5,285	2,122
Net cash provided by operating activities	54,959	67,501
Investing Activities:
Capital expenditures	(18,150)	(24,026)
Proceeds from the sale of property, plant and equipment, net	0	9
Return of capital from unconsolidated joint ventures	0	2,625
Net cash used in investing activities	(18,150)	(21,392)
Financing Activities:
Proceeds from borrowings under revolving credit facility	150,000	0
Repayment of debt principal and finance lease obligations	(50,193)	(33,196)
Payments of taxes related to net share settlement of equity awards	(5,029)	(7,424)
Proceeds from the exercise of stock options, net	0	327
Proceeds from issuance of shares to employee stock purchase plan	664	594
Net cash provided by (used in) financing activities	95,442	(39,699)
Effect of exchange rate fluctuations on cash	(358)	(1,080)
Net increase (decrease) in cash and cash equivalents	131,893	5,330
Cash and cash equivalents at beginning of period	166,849	167,738
Cash and cash equivalents at end of period	298,742	173,068
Supplemental Disclosures:
Accrued capital additions	4,144	2,119
Interest, net of amounts capitalized	3,311	4,440
Income taxes	$ 15,644	$ 9,164