Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Cash Flows [Abstract]
Cash, Including Discontinued Operations		$ 471,540	$ 27,711
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 136,089
Net (loss) earnings	(69,742)	209,829	54,169
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	692	153,383	38,292
Cash flows from operating activities:
Net (loss) earnings	(70,434)	56,446	15,877
Adjustments to reconcile earnings from continuing operations, net of tax to net cash provided by operating activities:
Depreciation and amortization	43,899	25,854	27,875
Amortization of debt issuance costs	1,746	1,996	1,806
Accretion of convertible notes discount	2,860	2,760	2,596
Provision for doubtful accounts	1,381	788	767
Impairment of Long-Lived Assets to be Disposed of	36,285	0	0
Gain (Loss) on Disposition of Business, Non Cash	(493)	3,971	5,722
Net loss (gain) on sale of assets	200	237	(1,031)
Goodwill and Intangible Asset Impairment	50,307	0	10,039
Net (gain) loss on derivative instruments	(466)	302	829
Stock compensation expense	4,979	4,669	5,484
Noncash Consideration on Sale of Aircraft	0	(3,100)	0
Deferred income taxes	(6,055)	182	7,834
Changes in assets and liabilities, excluding effects of acquisitions/divestitures:
Accounts receivable	7,042	(8,173)	(6,020)
Increase (Decrease) in Contract with Customer, Asset	12,629	(21,994)	(24,294)
increase (Decrease) in Capitalized Contract Cost	294	4,506	(5,834)
Inventories	(18,485)	(25,129)	7,135
Income tax refunds receivable	2,763	(6,296)	1,136
Increase (Decrease) in Operating Right of Use Assets	1,513	(3,390)	0
Other assets	2,490	(6,108)	(2,944)
Accounts payable - trade	(9,227)	14,034	10,807
Increase (Decrease) in Contract with Customer, Liability	(29,555)	(26,638)	96,430
Increase (Decrease) in Operating Lease Liabilities	(1,560)	(3,423)	0
Other current liabilities	16,955	6,085	(374)
Income taxes payable	(4,885)	7,888	(2,393)
Pension liabilities	(21,550)	4,170	(38,179)
Other long-term liabilities	(6,164)	6,071	5,446
Net Cash Provided by (Used in) Operating Activities, Continuing Operations	16,469	42,488	118,714
Cash Provided by (Used in) Operating Activities, Discontinued Operations	0	(50,288)	43,654
Net cash provided by operating activities from continuing operations	16,469	(7,800)	162,368
Cash flows from investing activities:
Proceeds from sale of assets	352	196	2,138
Proceeds from Divestiture of Businesses	5,223	655,030	0
Proceeds from Sales of Business, Affiliate and Productive Assets	493	0	0
Expenditures for property, plant & equipment	(17,783)	(22,447)	(21,504)
Acquisition of businesses including earn out adjustments, net of cash acquired	(304,661)	0	0
Other, net	(2,346)	(4,463)	(3,172)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations	(318,722)	628,316	(22,538)
Cash Provided by (Used in) Investing Activities, Discontinued Operations	0	(9,838)	(7,423)
Net cash (used in) provided by investing activities of continuing operations	(318,722)	618,478	(29,961)
Cash flows from financing activities:
Net repayments under revolving credit agreements	0	(38,500)	(98,087)
Proceeds from (Repayments of) Other Long-term Debt	0	(76,875)	(7,500)
Repayment of convertible notes	0	(500)	0
Net change in bank overdraft	(12)	886	(279)
Proceeds from exercise of employee stock awards	4,296	19,676	7,351
Purchase of treasury shares	(14,210)	(30,060)	(19,278)
Dividends paid	(22,210)	(22,343)	(22,349)
Debt and equity issuance costs	0	(3,584)	0
Other	(1,399)	(1,413)	(1,003)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations	(33,535)	(152,713)	(141,145)
Cash Provided by (Used in) Financing Activities, Discontinued Operations	0	7,967	(217)
Net cash used in financing activities of continuing operations	(33,535)	(144,746)	(141,362)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	(335,788)
Net (decrease) increase in cash and cash equivalents		465,932	(8,955)
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	0	(21,834)	(1,816)
Effect of exchange rate changes on cash and cash equivalents	337	(269)	(238)
Cash and cash equivalents and restricted cash at beginning of period	471,540	25,895
Cash and cash equivalents and restricted cash at end of period (See Note 2)	$ 104,377	$ 471,540	$ 25,895