CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities:
Net income	$ 87,651	$ 80,459	$ 48,283
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	50,073	44,099	37,847
Equity compensation expense	11,223	11,818	11,275
Deferred income taxes	(3,325)	17,513	7,382
Equity in undistributed income of unconsolidated joint ventures	(5,501)	(4,898)	(4,146)
Dividends received from unconsolidated joint ventures	4,431	3,529	2,757
Pension and other postretirement benefits	(1,552)	(1,561)	(2,822)
Asbestos-related charges	704	3,400	313
(Gain) loss on sale or disposal of property, plant and equipment	(164)	(5,154)	225
Impairment charges	1,506	807	0
Provision (benefit) for doubtful accounts	236	(439)	1,321
Proceeds from insurance related to operations	0	932	0
Changes in assets and liabilities:
Accounts receivable	(3,824)	(14,059)	(13,005)
Contract assets	(22,728)	0	0
Inventories	(19,013)	(14,208)	9,689
Pension and postretirement benefit contributions	(25,354)	(906)	(842)
Other current assets	(648)	(576)	1,933
Accounts payable and other accrued expenses	(7,886)	12,341	21,472
Other, net	991	5,885	(4,715)
Net cash provided by operating activities	66,820	138,982	116,967
Investing Activities:
Acquisition of business, net of cash received	(77,969)	(60,191)	(133,943)
Isola asset acquisition	(43,434)	0	0
Capital expenditures	(47,115)	(27,215)	(18,136)
Proceeds from the sale of property, plant and equipment, net	1,081	8,095	0
Proceeds from insurance claims	0	1,041	275
Net cash used in investing activities	(167,437)	(78,270)	(151,804)
Financing Activities:
Proceeds from borrowings under revolving credit facility	102,500	0	166,000
Line of credit issuance costs	0	(1,169)	0
Repayment of debt principal and capital lease obligations	(6,162)	(110,689)	(103,760)
Payments of taxes related to net share settlement of equity awards	(6,600)	(5,309)	(1,377)
Proceeds from the exercise of stock options, net	861	895	858
Proceeds from issuance of shares to employee stock purchase plan	1,082	3,085	4,143
Share repurchases	(2,999)	0	(7,995)
Net cash provided by (used in) financing activities	88,682	(113,187)	57,869
Effect of exchange rate fluctuations on cash	(1,486)	5,867	149
Net increase (decrease) in cash and cash equivalents	(13,421)	(46,608)	23,181
Cash and cash equivalents at beginning of period	181,159	227,767	204,586
Cash and cash equivalents at end of period	167,738	181,159	227,767
Supplemental Disclosures:
Accrued capital additions	2,744	2,376	1,081
Assets obtained under leasing arrangements	0	883	0
Interest, net of amounts capitalized	7,040	5,787	3,924
Income taxes	$ 29,161	$ 36,918	$ 23,952