CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended			79 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018	Dec. 26, 2020
Cash flows from operating activities:
Net earnings	$ 142,149	$ 152,105	$ 107,725
Adjustments to reconcile net earnings to net cash flows from operations:
Depreciation and amortization	82,892	82,264	82,827
Noncash loss on trading securities	39	(172)	(62)
Contribution to defined benefit pension plan	(35,399)	(18,461)	(1,537)
Impairment of property, plant and equipment	3,751	0	5,000
Impairment of goodwill & intangible assets	16,638	0	15,780
Loss on divestiture of grinding media business	0	0	6,084
Stock-based compensation	14,874	11,587	10,392
Defined benefit pension plan expense (benefit)	(7,311)	(513)	(2,251)
(Gain) loss on sale of property, plant and equipment	60	(2,513)	(225)
Equity in earnings in nonconsolidated subsidiaries	1,004	0	0
Deferred income taxes	(1,397)	1,486	814
Changes in assets and liabilities (net of acquisitions):
Receivables	(24,403)	5,408	12,571
Inventories	(21,888)	22,128	(23,666)
Prepaid expenses and other assets	(10,633)	4,413	(11,048)
Contract asset - costs and profits in excess of billings	19,835	(29,274)	(32,932)
Accounts payable	33,044	(21,410)	(1,486)
Accrued expenses	52,548	(4,255)	2,834
Contract liabilities	12,072	113,039	(2,785)
Other noncurrent liabilities	46,712	(1,274)	(10,888)
Income taxes payable (refundable)	(8,293)	(6,944)	(4,139)
Net cash flows from operating activities	316,294	307,614	153,008
Cash flows from investing activities:
Purchase of property, plant and equipment	(106,700)	(97,425)	(71,985)
Proceeds from sale of assets	10,860	5,556	63,103
Acquisitions, net of cash acquired	(15,862)	(81,841)	(143,020)
Proceeds from settlement of net investment hedge	11,983	11,184	(1,621)
Investments in nonconsolidated subsidiaries	(1,283)	(6,169)	0
Other, net	(3,027)	545	(1,922)
Net cash flows used in investing activities	(104,029)	(168,150)	(155,445)
Cash flows from financing activities:
Proceeds from short-term agreements	20,990	13,195	10,543
Payments on short-term agreements	(7,946)	(1,868)	0
Proceeds from long-term borrowings	88,872	31,000	251,655
Principal payments on long-term borrowings	(121,665)	(10,768)	(262,191)
Settlement of financial derivatives	0	0	(2,467)
Debt issuance costs	0	0	(2,322)
Dividends paid	(36,930)	(32,642)	(33,726)
Dividends to noncontrolling interest	(5,642)	(7,737)	(7,055)
Purchase of noncontrolling interest	(59,416)	(27,845)	(5,510)
Proceeds from exercises under stock plans	18,961	13,619	7,357
Purchase of treasury shares	(56,491)	(62,915)	(114,805)	$ (852,040)
Purchase of common treasury shares—stock plan exercises	(14,489)	(12,989)	(3,589)
Net cash flows used in financing activities	(173,756)	(98,950)	(162,110)
Effect of exchange rate changes on cash and cash equivalents	8,675	(182)	(15,048)
Net change in cash and cash equivalents	47,184	40,332	(179,595)
Cash, cash equivalents, and restricted cash—beginning of year	353,542	313,210	492,805
Cash, cash equivalents, and restricted cash—end of year	$ 400,726	$ 353,542	$ 313,210	$ 400,726