Note 1 - General (Details)	1 Months Ended	6 Months Ended		3 Months Ended						3 Months Ended	1 Months Ended				3 Months Ended		12 Months Ended	1 Months Ended	3 Months Ended
	Apr. 30, 2012 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 Scenario, Forecast [Member] Bayou Welding Works [Member] USD ($)	Jun. 30, 2013 Bayou Welding Works [Member] Goodwill and Intagible Assets [Member] USD ($)	Jun. 30, 2013 Bayou Welding Works [Member] Tangible Assets [Member] USD ($)	Jun. 30, 2013 Bayou Welding Works [Member] USD ($)	Jun. 30, 2013 USTS [Member]	Mar. 31, 2012 USTS [Member]	Jun. 30, 2013 Bayou Coating [Member] USD ($)	Jun. 30, 2013 Insituform-Germany [Member] USD ($)	Jun. 30, 2013 Insituform-Germany [Member] EUR (€)	Jun. 30, 2013 Insituform-Germany [Member] GBP (£)	Apr. 30, 2012 Fyfe Asia [Member] USD ($)	Dec. 31, 2012 Fyfe Asia [Member] USD ($)	Mar. 31, 2012 Fyfe Asia [Member] USD ($)	Dec. 31, 2012 Fyfe Asia [Member] USD ($)	Jan. 31, 2012 Fyfe LA [Member] USD ($)	Mar. 31, 2012 Fyfe LA [Member] USD ($)
Note 1 - General (Details) [Line Items]
Goodwill and Intangible Asset Impairment							$ 3,900,000
Goodwill and Intangible Asset Impairment, Net of Tax							2,400,000
Impairment Effect on Earnings Per Share, after Tax (in Dollars per share)					$ 0.06	$ 0.02
Tangible Asset Impairment Charges							1,100,000
Tangible Asset Impairment Charges, Net of Tax							700,000
Proceeds from Sale of Property, Plant, and Equipment		1,637,000	2,849,000	9,900,000
Business Exit Costs				100,000
Business Exit Costs Effect on Earnings Per Share, after Tax				0.01
Noncontrolling Interest, Ownership Percentage by Parent									51.00%		50.00%	50.00%	50.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners									49.00%
Percent of Book Value								49.00%
Equity Method Investment, Other than Temporary Impairment										2,700,000
Equity Method Investment, Other than Temporary Impairment, Net of Tax										1,800,000
Business Combination, Consideration Transferred (in Euro)	40,144,000										18,300,000	14,000,000
Business Combination, Consideration Transferred	40,144,000										18,300,000	14,000,000
Gain (Loss) on Disposition of Business											11,300,000
Business Acquisition, Transaction Costs											500,000
Long-term Purchase Commitment, Amount (in Pounds)											3,600,000		2,300,000
Long-term Purchase Commitment, Amount											3,600,000		2,300,000
Number of Joint Ventures														2
Payments to Acquire Businesses, Gross														40,700,000		40,700,000	40,100,000	2,300,000
Proceeds from Lines of Credit			26,000,000											18,000,000
Payments for Previous Acquisition		2,112,000																	1,100,000
Proceeds from Previous Acquisition															$ 600,000