Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Apr. 02, 2021	Apr. 03, 2020	Dec. 31, 2020	Dec. 31, 2018
Statement of Cash Flows [Abstract]
Net earnings	$ 7,984	$ 285
Earnings from discontinued operations, net of tax	0	692
Earnings from continuing operations	7,984	(407)
Adjustments to reconcile net earnings from continuing operations to net cash (used in) provided by operating activities of continuing operations:
Depreciation and amortization	9,209	9,509
Amortization of debt issuance costs	424	492
Accretion of convertible notes discount	738	702
Provision for doubtful accounts	173	179
Goodwill, Impairment Loss	0
Gain (Loss) on Disposition of Business	234	(493)
Net loss (gain) on sale of assets	10	(10)
Net loss on derivative instruments	590	983
Stock compensation expense	1,743	1,633
Deferred income taxes	1,793	3,493
Changes in assets and liabilities, excluding effects of acquisitions/divestitures:
Accounts receivable	50,254	(6,531)
Increase (Decrease) in Contract with Customer, Asset	(5,704)	(11,665)
Contract costs	(432)	(709)
Inventories	(13,655)	(25,206)
Income tax refunds receivable	418	(2,078)
Operating Right-of-Use Assets	799	1,223
Other assets	1,042	(917)
Accounts payable - trade	(14,707)	(6,405)
Contract liabilities	(5,439)	1,743
Operating Lease Liabilities	(908)	(1,183)
Payments for Retention Plans	(25,108)	0
Other current liabilities	(6,796)	(8,079)
Income taxes payable	1,173	(1,038)
Pension liabilities	(5,452)	(12,887)
Increase (Decrease) in Other Noncurrent Liabilities	(798)	2,209
Net Cash Provided by Operating Activities of Continuing Operations	(2,415)	(55,442)
Net Cash (Used in) Provided by Operating Activities of Discontinued Operations	0	0
Net cash provided by operating activities	(2,415)	(55,442)
Cash flows from investing activities:
Proceeds from sale of assets	54	11
Proceeds from Divestiture of Businesses	0	5,223
Payments for (Proceeds from) Businesses and Interest in Affiliates	(3,428)
Proceeds from Sales of Business, Affiliate and Productive Assets		493
Expenditures for property, plant & equipment	(4,678)	(5,559)
Payments to Acquire Businesses, Net of Cash Acquired	0	(304,342)
Other, net	(48)	394
Net Cash Used in Investing Activities of Continuing Operations	(8,100)	(303,780)
Net Cash Used in Investing Activities of Discontinued Operations	0	0
Net cash used in investing activities	(8,100)	(303,780)
Cash flows from financing activities:
Net borrowings under revolving credit agreements	0	201,100
Net change in bank overdraft	797	371
Proceeds from exercise of employee stock awards	880	1,455
Purchase of treasury shares	(344)	(14,072)
Dividends paid	(5,545)	(5,595)
Other, net	(472)	(381)
Net Cash Provided by Financing Activities of Continuing Operations	(4,684)	182,878
Net Cash (Used in) Provided by Financing Activities of Discontinued Operations	0	0
Net cash provided by (used in) financing activities	(4,684)	182,878
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	(15,199)	(176,344)
Effect of exchange rate changes on cash and cash equivalents	(166)	262
Cash and cash equivalents at beginning of period				$ 471,540
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	120,724		$ 136,089
Cash and cash equivalents and restricted cash at end of period	$ 120,724	$ 295,458	$ 104,377