Note 1 - Description of Business (Details)	0 Months Ended	1 Months Ended			3 Months Ended						9 Months Ended	12 Months Ended						3 Months Ended			12 Months Ended				3 Months Ended				3 Months Ended					3 Months Ended			12 Months Ended					12 Months Ended		3 Months Ended	12 Months Ended			3 Months Ended	24 Months Ended
	Jul. 01, 2013 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2013 EUR (€)	Apr. 30, 2012 USD ($) jointVenture	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2013 EUR (€)	Jun. 30, 2013 USD ($)	Mar. 31, 2012 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) geographies		Dec. 31, 2013 USD ($)		Dec. 31, 2012 USD ($)		Jun. 30, 2013 Goodwill and Intagible Assets [Member] USD ($)	Jun. 30, 2013 Tangible Assets [Member] USD ($)	Dec. 31, 2014 Brinderson LP [Member] USD ($)	Dec. 31, 2014 Brinderson LP [Member] USD ($)	Dec. 31, 2013 Brinderson LP [Member] USD ($)	Jul. 02, 2013 Brinderson LP [Member] USD ($)	Jul. 01, 2013 Brinderson LP [Member] USD ($)	Jun. 30, 2014 Fyfe Asia [Member] USD ($)	Dec. 31, 2014 Fyfe Asia [Member] USD ($)	Dec. 31, 2013 Fyfe Asia [Member] USD ($)	Dec. 31, 2013 Fyfe LA [Member] USD ($)	Dec. 31, 2014 Ka-te [Member] USD ($)	Dec. 31, 2014 CRTS [Member] USD ($)	Sep. 30, 2014 CRTS [Member] USD ($)	Jun. 30, 2012 USTS [Member]	Mar. 31, 2012 USTS [Member]	Sep. 30, 2014 Bayou Coating [Member] USD ($)	Mar. 31, 2014 Bayou Coating [Member] USD ($)	Sep. 30, 2013 Bayou Coating [Member] USD ($)	Dec. 31, 2014 Bayou Coating [Member] USD ($)	Dec. 31, 2013 Bayou Coating [Member] USD ($)	Dec. 31, 2012 Bayou Coating [Member] USD ($)	Mar. 31, 2014 Delta Double Jointing [Member]	Dec. 31, 2014 Brinderson LP [Member] USD ($)	Dec. 31, 2014 2013 Credit Facility [Member] USD ($)	Jul. 31, 2013 2013 Credit Facility [Member] USD ($)	Dec. 31, 2014 Bayou Welding Works [Member] USD ($)	Dec. 31, 2014 Bayou Welding Works [Member] USD ($)	Dec. 31, 2013 Bayou Welding Works [Member] USD ($)	Dec. 31, 2012 Bayou Welding Works [Member] USD ($)	Dec. 31, 2014 Operating Expense [Member] Brinderson LP [Member] USD ($)	Jun. 30, 2015 Scenario, Forecast [Member] USD ($)	Jun. 30, 2015 Scenario, Forecast [Member] GBP (£)
General [Line Items]
Number of Countries in which Entity Operates												80
Number of Continents on Which the Company Operates												6
Number of Years in Which the Company has Operated												40
Proceeds from Divestiture of Businesses												$ 1,123,000		$ 0		$ 0													$ 1,100,000
Goodwill												293,023,000		348,680,000						76,248,000	76,248,000	77,248,000				21,106,000	20,008,000			14,400,000	20,100,000
Goodwill, Acquired During Period												100,000	[1],[2]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net																				146,600,000	146,600,000		147,600,000	147,600,000
Goodwill, Purchase Accounting Adjustments																				1,000,000	(1,000,000)				(1,098,000)																							(4,500,000)
Debt Instrument, Face Amount																																											650,000,000
Payments for (Proceeds from) Previous Acquisition																				5,500,000
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					11,870,000				1,100,000
Tangible Asset Impairment Charges, Net of Tax									700,000
Business Exit Costs									100,000																																				0	5,019,000	0
Business Combination, Contingent Consideration, Amounts Paid												0		2,112,000		0
Earnout reversal												0		(4,175,000)		(10,019,000)
Business Combination, Contingent Consideration, Liability																												0
Noncontrolling Interest, Ownership Percentage by Parent		50.00%	50.00%						50.00%																								51.00%							59.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners																																49.00%			51.00%					41.00%
Payments to Noncontrolling Interests						617,000						617,000		287,000		5,000
Proceeds from Divestiture of Interest in Joint Venture						9,065,000																															9,065,000	0	0
PercentOfBookValue																																			49.00%
Equity Method Investment, Other than Temporary Impairment																																				2,700,000
EquityMethodInvestmentOtherThanTemporaryImpairmentNetOfTax																																				1,800,000
Total consideration recorded		18,300,000	14,000,000				18,300,000	14,000,000													146,605,000
Gain (Loss) on Disposition of Business		11,300,000					11,300,000					(516,000)		0		0
Business Acquisition, Transaction Costs		500,000					500,000		500,000
Long-term Purchase Commitment, Amount (in Pounds)																																																	3,600,000	2,300,000
NumberOfJointVentures				2
Payments to Acquire Businesses, Gross	150,000,000			40,700,000						2,300,000		150,000,000
Proceeds from line of credit				18,000,000								18,000,000		0		26,000,000																										10,000,000
Payments for Previous Acquisition										1,100,000
Loss Contingency Accrual																																									14,500,000
Income (Loss) from Equity Method Investments												570,000	[3]	5,159,000	[4]	6,359,000	[4]																	1,200,000	1,200,000
Proceeds from Equity Method Investment, Dividends or Distributions						684,000					684,000	590,000		10,691,000		11,034,000
Gain (Loss) on Sale of Equity Investments																																					(472,000)	0	0
Disposal Group, Including Discontinued Operation, General and Administrative Expense																																												1,400,000
Disposal Group, Including Discontinued Operation, Operating Income (Loss)																																													$ (6,008,000)	$ (11,247,000)	$ 2,683,000

[1] During the second quarter of 2014, the Company recorded goodwill of $1.1 million related to the 2012 acquisition of Fyfe Asia (see Note 1).

[2] During the fourth quarter of 2014, the Company decreased goodwill by $1.0 million related to the 2013 acquisition of Brinderson (see Note 1)

[3] Bayou Coating was sold in March 2014. Income statement data in 2014 includes only those results up to the date of its sale.

[4] Includes the financial data of Insituform-Germany through the date of its sale in June 2013.