Retirement plans Plan assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Prohibited Investments	The plans hold no securities of MFRI, Inc.
Defined Benefit Plan, Actual Plan Asset Allocations	100.00%
Defined Benefit Plan, Fair Value of Plan Assets	$ 5,883	$ 6,168	$ 6,351
Defined Benefit Plan, Target Allocation Percentage	target asset allocations of 52% equities (with a range of 40% - 65%),  30% fixed income (with a range of 20% - 35%) and 18% Alternative Investments (with a range of 15% - 25%)
Defined benefit -plan, actual gain on plan assets	$ (25)	$ 63
Net periodic benefit cost, expected long-term return on assets	8.00%	8.00%
Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	61.00%
Available-for-sale Securities, Equity Securities	$ 3,062	$ 3,795
Bonds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	31.00%
Available-for-sale Securities	$ 2,168	2,033
Money Market Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	8.00%
Money Market Funds, at Carrying Value	$ 351	340
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities	5,230	5,828
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Available-for-sale Securities, Equity Securities	302	0
Available-for-sale Securities	$ 653	$ 340