CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 27, 2014	Dec. 28, 2013	Dec. 29, 2012
Cash flows from operating activities:
Net earnings	$ 189,318us-gaap_ProfitLoss	$ 280,460us-gaap_ProfitLoss	$ 238,916us-gaap_ProfitLoss
Adjustments to reconcile net earnings to net cash flows from operations:
Depreciation and amortization	89,328	77,436	70,218
Loss on investment	3,795us-gaap_GainLossOnInvestments
Deconsolidation of subsidiary		12,011
Impairment of property, plant and equipment	0	12,161
Non-cash debt refinancing costs	(2,478)vmi_NoncashDebtRefinancingCosts
Stock-based compensation	6,730us-gaap_ShareBasedCompensation	6,513us-gaap_ShareBasedCompensation	5,829us-gaap_ShareBasedCompensation
Defined benefit pension plan expense	2,638us-gaap_PensionExpense	6,569us-gaap_PensionExpense	4,281us-gaap_PensionExpense
Contribution to defined benefit pension plan	(18,173)us-gaap_PensionContributions	(17,619)us-gaap_PensionContributions	(11,591)us-gaap_PensionContributions
Change in fair value of contingent consideration	(4,300)vmi_ReversalOfContingentConsideration
(Gain) loss on sale of property, plant and equipment	392	(4,318)	321
Equity in earnings in nonconsolidated subsidiaries	(29)	(835)	(6,128)
Deferred income taxes	5,251us-gaap_DeferredIncomeTaxExpenseBenefit	(10,141)us-gaap_DeferredIncomeTaxExpenseBenefit	3,720us-gaap_DeferredIncomeTaxExpenseBenefit
Changes in assets and liabilities (net of the effect from acquisitions):
Receivables	907us-gaap_IncreaseDecreaseInReceivables	(12,708)us-gaap_IncreaseDecreaseInReceivables	(84,890)us-gaap_IncreaseDecreaseInReceivables
Inventories	21,458us-gaap_IncreaseDecreaseInInventories	13,431us-gaap_IncreaseDecreaseInInventories	(13,613)us-gaap_IncreaseDecreaseInInventories
Prepaid expenses	(13,594)	4,115	1,243
Accounts payable	(34,321)	12,448	(6,249)
Accrued expenses	(34,778)	21,698	20,640
Other noncurrent liabilities	1,755	(1,474)	(4,350)
Income taxes payable (refundable)	(39,803)	(3,305)	(21,250)
Net cash flows from operating activities	174,096	396,442	197,097
Cash flows from investing activities:
Purchase of property, plant and equipment	(73,023)	(106,753)	(97,074)
Acquisitions (net of cash acquired)	(185,710)	(63,152)	(45,687)
Proceeds from sale of assets	2,489	37,582	6,025
Other, net	(619)	602	44
Net cash flows from investing activities	(256,863)	(131,721)	(136,692)
Cash flows from financing activities:
Net borrowings under short-term agreements	(4,472)	5,510	1,828
Proceeds from long-term borrowings	652,211	274	39,126
Principal payments on long-term obligations	(357,858)us-gaap_RepaymentsOfLongTermDebt	(591)us-gaap_RepaymentsOfLongTermDebt	(39,564)us-gaap_RepaymentsOfLongTermDebt
Cash decrease due to deconsolidation of subsidiary		(11,615)
Dividends paid	(32,443)us-gaap_PaymentsOfDividendsCommonStock	(25,414)us-gaap_PaymentsOfDividendsCommonStock	(21,520)us-gaap_PaymentsOfDividendsCommonStock
Dividends to noncontrolling interest	(2,919)	(1,767)	(1,944)
Purchase of noncontrolling interest		(9,324)
Proceeds from sale of partial ownership interest			1,404
Settlement of financial derivative	4,981
Debt issuance fees	(7,644)us-gaap_PaymentsOfDebtIssuanceCosts		(1,747)us-gaap_PaymentsOfDebtIssuanceCosts
Proceeds from exercises under stock plans	14,572us-gaap_ProceedsFromStockPlans	16,348us-gaap_ProceedsFromStockPlans	21,827us-gaap_ProceedsFromStockPlans
Excess tax benefits from stock option exercises	4,264	5,306	5,494
Purchase of treasury shares	(395,045)
Purchase of common treasury shares-stock plan exercises	(15,403)	(16,107)	(21,259)
Net cash flows from financing activities	(139,756)	(37,380)	(16,355)
Effect of exchange rate changes on cash and cash equivalents	(19,604)	(27,764)	7,185
Net change in cash and cash equivalents	(242,127)	199,577	51,235
Cash and cash equivalents-beginning of year	613,706	414,129	362,894
Cash and cash equivalents-end of year	$ 371,579	$ 613,706	$ 414,129

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.