GUARANTOR/NON-GUARANTOR FINANCIAL INFORMATION (Details 5) - USD ($)	12 Months Ended			56 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Dec. 29, 2018	Dec. 26, 2015
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Defined benefit pension plan expense (benefit)	$ (2,251,000)	$ 648,000	$ 1,870,000
Cash flows from operating activities:
Net earnings	100,306,000	122,319,000	178,391,000
Adjustments to reconcile net earnings to net cash flows from operations:
Depreciation and amortization	82,827,000	84,957,000	82,417,000
Noncash loss on trading securities	(62,000)	237,000	586,000
Impairment of property, plant and equipment	5,000,000	0	1,099,000
Impairment of property, plant and equipment	15,780,000	0	0
Loss from divestiture of grinding media business	6,084,000	0	0
Stock-based compensation	10,392,000	10,706,000	9,931,000
Contribution to defined benefit pension plan	(1,537,000)	(40,245,000)	(1,488,000)
(Gain) loss on sale of property, plant and equipment	(225,000)	(3,924,000)	631,000
Equity in earnings in nonconsolidated subsidiaries	0	0	0
Deferred income taxes	(1,659,000)	39,755,000	(23,685,000)
Net working capital	46,620,000	75,185,000	(2,196,000)
Changes in assets and liabilities (net of acquisitions):
Inventories	(13,774,000)	(57,442,000)	(11,461,000)
Prepaid expenses	(11,048,000)	(6,214,000)	(1,925,000)
Accounts payable	(1,486,000)	39,405,000	104,000
Accrued expenses	49,000	(1,998,000)	(12,207,000)
Other noncurrent liabilities	(10,888,000)	(7,228,000)	(23,880,000)
Income taxes payable (refundable)	(4,139,000)	1,108,000	7,994,000
Net cash flows from operating activities	153,008,000	133,148,000	232,820,000
Change in fair value of contingent consideration	0	0	(3,242,000)
Cash flows from investing activities:
Purchase of property, plant and equipment	(71,985,000)	(55,266,000)	(57,920,000)
Proceeds from sale of assets	63,103,000	8,185,000	5,126,000
Acquisitions, net of cash acquired	(143,020,000)	(5,362,000)	0
Proceeds from settlement of net investment hedge	(1,621,000)	5,123,000	0
Other, net	(1,922,000)	(2,295,000)	(255,000)
Net cash flows used in investing activities	(155,445,000)	(49,615,000)	(53,049,000)
Cash flows from financing activities:
Borrowings (Payments) under short-term agreements	10,543,000	(585,000)	(200,000)
Proceeds from long-term borrowings	251,655,000	0	0
Principal payments on long-term borrowings	(262,191,000)	(887,000)	(2,006,000)
Payments for Derivative Instrument, Financing Activities	2,467,000	0	0
Dividends paid	(33,726,000)	(33,862,000)	(34,053,000)
Dividends to noncontrolling interest	(7,055,000)	(5,674,000)	(2,938,000)
Increase (Decrease) Payments of Intercompany Dividends	0	0
vmi_ProceedsFromRepaymentOfIntercompanyCapitalContribution	0	0
Purchase of noncontrolling interest	(5,510,000)	0	(11,009,000)
Debt issuance costs	(2,322,000)	0	0
Proceeds from exercises under stock plans	7,357,000	35,159,000	11,153,000
Purchase of treasury shares	(114,805,000)	0	(53,800,000)	$ (732,600,000)
Purchase of common treasury shares - stock plan exercises	(3,589,000)	(26,161,000)	(2,305,000)
Net cash flows used in financing activities	(162,110,000)	(32,010,000)	(95,158,000)
Effect of exchange rate changes on cash and cash equivalents	(15,048,000)	27,682,000	(20,087,000)
Net change in cash and cash equivalents	(179,595,000)	79,205,000	64,526,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	313,210,000	492,805,000	413,600,000	313,210,000	$ 349,074,000
Eliminations
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Defined benefit pension plan expense (benefit)	0	0	0
Cash flows from operating activities:
Net earnings	(104,164,000)	(105,852,000)	(208,027,000)
Adjustments to reconcile net earnings to net cash flows from operations:
Depreciation and amortization	0	0	0
Noncash loss on trading securities	0	0	0
Impairment of property, plant and equipment	0		0
Impairment of property, plant and equipment	0
Loss from divestiture of grinding media business	0
Stock-based compensation	0	0	0
Contribution to defined benefit pension plan	0	0	0
(Gain) loss on sale of property, plant and equipment	0	0	0
Equity in earnings in nonconsolidated subsidiaries	105,687,000	106,023,000	207,189,000
Deferred income taxes	0	0	0
Net working capital	1,769,000	306,000	(1,160,000)
Changes in assets and liabilities (net of acquisitions):
Other noncurrent liabilities	0	0	0
Income taxes payable (refundable)	0	0	0
Net cash flows from operating activities	(246,000)	(135,000)	322,000
Change in fair value of contingent consideration			0
Cash flows from investing activities:
Purchase of property, plant and equipment	0	0	0
Proceeds from sale of assets	0	0	0
Acquisitions, net of cash acquired	0	0
Proceeds from settlement of net investment hedge	0	0
Other, net	246,000	135,000	(322,000)
Net cash flows used in investing activities	246,000	135,000	(322,000)
Cash flows from financing activities:
Borrowings (Payments) under short-term agreements	0	0	0
Proceeds from long-term borrowings	0
Principal payments on long-term borrowings	0	0	0
Payments for Derivative Instrument, Financing Activities	0
Dividends paid	0	0	0
Dividends to noncontrolling interest	0	0	0
Increase (Decrease) Payments of Intercompany Dividends	0	0
vmi_ProceedsFromRepaymentOfIntercompanyCapitalContribution	0	0
Purchase of noncontrolling interest	0		0
Debt issuance costs	0
Proceeds from exercises under stock plans	0	0	0
Purchase of treasury shares	0		0
Purchase of common treasury shares - stock plan exercises	0	0	0
Net cash flows used in financing activities	0	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	0	0	0	0	0
Parent
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Defined benefit pension plan expense (benefit)	0	0	0
Cash flows from operating activities:
Net earnings	94,351,000	116,240,000	173,232,000
Adjustments to reconcile net earnings to net cash flows from operations:
Depreciation and amortization	26,155,000	26,237,000	27,096,000
Noncash loss on trading securities	0	0	0
Impairment of property, plant and equipment	0		0
Impairment of property, plant and equipment	0
Loss from divestiture of grinding media business	(2,518,000)
Stock-based compensation	10,392,000	10,706,000	9,931,000
Contribution to defined benefit pension plan	0	0	0
(Gain) loss on sale of property, plant and equipment	57,000	(664,000)	165,000
Equity in earnings in nonconsolidated subsidiaries	(68,383,000)	(83,877,000)	(141,061,000)
Deferred income taxes	1,532,000	10,307,000	6,216,000
Net working capital	17,681,000	23,943,000	12,335,000
Changes in assets and liabilities (net of acquisitions):
Other noncurrent liabilities	(7,345,000)	(140,000)	(2,333,000)
Income taxes payable (refundable)	(6,176,000)	(11,837,000)	32,873,000
Net cash flows from operating activities	35,420,000	43,029,000	93,784,000
Change in fair value of contingent consideration			0
Cash flows from investing activities:
Purchase of property, plant and equipment	(25,255,000)	(20,460,000)	(9,031,000)
Proceeds from sale of assets	44,000	748,000	44,000
Acquisitions, net of cash acquired	(57,805,000)	0
Proceeds from settlement of net investment hedge	(1,621,000)	5,123,000
Other, net	69,714,000	684,000	(633,000)
Net cash flows used in investing activities	(14,923,000)	(13,905,000)	(9,620,000)
Cash flows from financing activities:
Borrowings (Payments) under short-term agreements	0	0	0
Proceeds from long-term borrowings	245,936,000
Principal payments on long-term borrowings	(261,219,000)	0	(215,000)
Payments for Derivative Instrument, Financing Activities	2,467,000
Dividends paid	(33,726,000)	(33,862,000)	(34,053,000)
Dividends to noncontrolling interest	0	0	0
Increase (Decrease) Payments of Intercompany Dividends	(168,757,000)	(22,662,000)
vmi_ProceedsFromRepaymentOfIntercompanyCapitalContribution	(3,492,000)	10,818,000
Purchase of noncontrolling interest	0		0
Debt issuance costs	(2,322,000)
Proceeds from exercises under stock plans	7,357,000	35,159,000	11,153,000
Purchase of treasury shares	(114,805,000)		(53,800,000)
Purchase of common treasury shares - stock plan exercises	(3,589,000)	(26,161,000)	(2,305,000)
Net cash flows used in financing activities	430,000	(13,020,000)	(79,220,000)
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	20,927,000	16,104,000	4,944,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	104,256,000	83,329,000	67,225,000	104,256,000	62,281,000
Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Defined benefit pension plan expense (benefit)	0	0	0
Cash flows from operating activities:
Net earnings	77,679,000	52,562,000	104,625,000
Adjustments to reconcile net earnings to net cash flows from operations:
Depreciation and amortization	13,959,000	15,003,000	13,316,000
Noncash loss on trading securities	0	0	0
Impairment of property, plant and equipment	0		0
Impairment of property, plant and equipment	0
Loss from divestiture of grinding media business	0
Stock-based compensation	0	0	0
Contribution to defined benefit pension plan	0	0	0
(Gain) loss on sale of property, plant and equipment	(37,000)	8,000	103,000
Equity in earnings in nonconsolidated subsidiaries	(37,304,000)	(22,146,000)	(66,128,000)
Deferred income taxes	1,791,000	0	0
Net working capital	13,962,000	25,717,000	5,939,000
Changes in assets and liabilities (net of acquisitions):
Other noncurrent liabilities	615,000	0	5,000
Income taxes payable (refundable)	(1,303,000)	728,000	(16,567,000)
Net cash flows from operating activities	41,438,000	20,438,000	29,415,000
Change in fair value of contingent consideration			0
Cash flows from investing activities:
Purchase of property, plant and equipment	(13,115,000)	(9,454,000)	(22,320,000)
Proceeds from sale of assets	268,000	3,000	102,000
Acquisitions, net of cash acquired	0	0
Proceeds from settlement of net investment hedge	0	0
Other, net	(42,667,000)	(22,777,000)	(5,085,000)
Net cash flows used in investing activities	(55,514,000)	(32,228,000)	(27,303,000)
Cash flows from financing activities:
Borrowings (Payments) under short-term agreements	0	0	0
Proceeds from long-term borrowings	0
Principal payments on long-term borrowings	0	0	0
Payments for Derivative Instrument, Financing Activities	0
Dividends paid	0	0	0
Dividends to noncontrolling interest	0	0	0
Increase (Decrease) Payments of Intercompany Dividends	(11,296,000)	0
vmi_ProceedsFromRepaymentOfIntercompanyCapitalContribution	3,492,000	(10,818,000)
Purchase of noncontrolling interest	0		0
Debt issuance costs	0
Proceeds from exercises under stock plans	0	0	0
Purchase of treasury shares	0		0
Purchase of common treasury shares - stock plan exercises	0	0	0
Net cash flows used in financing activities	14,788,000	10,818,000	0
Effect of exchange rate changes on cash and cash equivalents	(498,000)	205,000	(49,000)
Net change in cash and cash equivalents	214,000	(767,000)	2,063,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	5,518,000	5,304,000	6,071,000	5,518,000	4,008,000
Non- Guarantors
Condensed consolidated financial information for the Company (Parent), the guarantor subsidiaries and the non-guarantor subsidiaries
Defined benefit pension plan expense (benefit)	(2,251,000)	648,000	1,870,000
Cash flows from operating activities:
Net earnings	32,440,000	59,369,000	108,561,000
Adjustments to reconcile net earnings to net cash flows from operations:
Depreciation and amortization	42,713,000	43,717,000	42,005,000
Noncash loss on trading securities	(62,000)	237,000	586,000
Impairment of property, plant and equipment	5,000,000		1,099,000
Impairment of property, plant and equipment	15,780,000
Loss from divestiture of grinding media business	(3,566,000)
Stock-based compensation	0	0	0
Contribution to defined benefit pension plan	1,537,000	(40,245,000)	(1,488,000)
(Gain) loss on sale of property, plant and equipment	(245,000)	(3,268,000)	363,000
Equity in earnings in nonconsolidated subsidiaries	0	0	0
Deferred income taxes	(4,982,000)	29,448,000	(29,901,000)
Net working capital	13,208,000	25,219,000	(19,310,000)
Changes in assets and liabilities (net of acquisitions):
Other noncurrent liabilities	(4,158,000)	(7,088,000)	(21,552,000)
Income taxes payable (refundable)	3,340,000	12,217,000	(8,312,000)
Net cash flows from operating activities	76,396,000	69,816,000	109,299,000
Change in fair value of contingent consideration			(3,242,000)
Cash flows from investing activities:
Purchase of property, plant and equipment	(33,615,000)	(25,352,000)	(26,569,000)
Proceeds from sale of assets	62,791,000	7,434,000	4,980,000
Acquisitions, net of cash acquired	(85,215,000)	(5,362,000)
Proceeds from settlement of net investment hedge	0	0
Other, net	(29,215,000)	19,663,000	5,785,000
Net cash flows used in investing activities	(85,254,000)	(3,617,000)	(15,804,000)
Cash flows from financing activities:
Borrowings (Payments) under short-term agreements	10,543,000	(585,000)	(200,000)
Proceeds from long-term borrowings	5,719,000
Principal payments on long-term borrowings	(972,000)	(887,000)	(1,791,000)
Payments for Derivative Instrument, Financing Activities	0
Dividends paid	0	0	0
Dividends to noncontrolling interest	(7,055,000)	(5,674,000)	(2,938,000)
Increase (Decrease) Payments of Intercompany Dividends	180,053,000	22,662,000
vmi_ProceedsFromRepaymentOfIntercompanyCapitalContribution	0	0
Purchase of noncontrolling interest			(11,009,000)
Debt issuance costs	0
Proceeds from exercises under stock plans	0	0	0
Purchase of treasury shares	0		0
Purchase of common treasury shares - stock plan exercises	0	0	0
Net cash flows used in financing activities	(177,328,000)	(29,808,000)	(15,938,000)
Effect of exchange rate changes on cash and cash equivalents	(14,550,000)	27,477,000	(20,038,000)
Net change in cash and cash equivalents	(200,736,000)	63,868,000	57,519,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	203,436,000	$ 404,172,000	$ 340,304,000	$ 203,436,000	$ 282,785,000
Non- Guarantors
Cash flows from financing activities:
Purchase of noncontrolling interest	$ (5,510,000)