EARNINGS PER SHARE (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ (32,960,000)	$ (45,664,000)	$ (72,241,000)	$ (84,643,000)
Shares outstanding basic (in shares)	22,438,000	22,517,000	22,523,000	22,494,000
Per share amount basic (in dollars per share)	$ 1.47	$ 2.03	$ 3.21	$ 3.76
Dilutive Effect of Stock Options
Dilutive Effect of Stock Options	$ 0	$ 0	$ 0	$ 0
Dilutive effect of stock options number of shares (in shares)	135,000	223,000	161,000	206,000
Dilutive effect of stock options (in dollars per share)	$ (0.01)	$ (0.02)	$ (0.03)	$ (0.03)
Diluted EPS
Diluted EPS	$ 32,960,000	$ 45,664,000	$ 72,241,000	$ 84,643,000
Shares outstanding dilutive (in shares)	22,573,000	22,740,000	22,684,000	22,700,000
Per share amount diluted (in dollars per share)	$ 1.46	$ 2.01	$ 3.18	$ 3.73
Antidilutive Securities
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	145,105	84,712	145,105	84,712
2018 Restructuring Plan
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ 6,295,000		$ 9,620,000
Per share amount basic (in dollars per share)	$ (0.28)		$ (0.43)
Diluted EPS
Diluted EPS	$ 6,345,000		$ 9,620,000
Per share amount diluted (in dollars per share)	$ 0.28		$ 0.43
Donhad | Disposed by sale
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ (5,455,000)
Per share amount basic (in dollars per share)	$ 0.24
Diluted EPS
Diluted EPS	$ 5,455,000
Per share amount diluted (in dollars per share)	$ 0.24