Note 1 - Description of Business (Detail) (USD $)	3 Months Ended	12 Months Ended														12 Months Ended		3 Months Ended	12 Months Ended								12 Months Ended		12 Months Ended		24 Months Ended			3 Months Ended	12 Months Ended			1 Months Ended	3 Months Ended	12 Months Ended	6 Months Ended
	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Aug. 31, 2011 Paid at Closing [Member] Hockway [Member]	Aug. 31, 2011 Paid at Closing [Member] Fyfe NA [Member]	Jan. 04, 2012 Paid at Closing [Member] Fyfe LA [Member]	Dec. 31, 2012 Earnout 1 [Member] Fyfe LA [Member]	Dec. 31, 2012 Earnout 2 [Member] Fyfe LA [Member]	Dec. 31, 2009 BPPC [Member]	Feb. 28, 2010 Bayou Delta [Member]	Dec. 31, 2009 Bayou Delta [Member]	Apr. 30, 2011 Bayou Wasco [Member]	Apr. 30, 2011 WCU [Member]	Jun. 30, 2011 Corrpower [Member]	Dec. 31, 2012 CRTS [Member]	Jun. 30, 2011 CRTS [Member]	Mar. 31, 2012 Hockway [Member]	Dec. 31, 2012 Hockway [Member]	Aug. 31, 2011 Hockway [Member]		Oct. 30, 2011 UPS-Aptec Limited [Member]	Oct. 21, 2011 UPS-Aptec Limited [Member] mi	Dec. 31, 2011 USTS [Member]	Jan. 31, 2010 Insituform-Singapore Subsidiary [Member]	Nov. 30, 2012 SPML [Member]	Dec. 31, 2012 SPML Joint Ventures [Member]	Nov. 30, 2012 SPML Joint Ventures [Member]	Dec. 31, 2012 Fyfe NA [Member]	Dec. 31, 2011 Fyfe NA [Member]	Dec. 31, 2012 Fyfe NA [Member]	Aug. 31, 2011 Fyfe NA [Member]		Mar. 31, 2012 Fyfe LA [Member]	Dec. 31, 2012 Fyfe LA [Member]	Jan. 31, 2012 Fyfe LA [Member]		Apr. 30, 2012 Fyfe Asia [Member]	Dec. 31, 2012 Fyfe Asia [Member]	Dec. 31, 2012 Fyfe LA and Fyfe Asia [Member]	Dec. 31, 2011 CRTS, Hockway and Fyfe NA [Member]
Noncontrolling Interest, Ownership Percentage by Parent										51.00%	59.00%		51.00%		70.00%							51.00%		51.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners											41.00%				30.00%							49.00%		49.00%
Equity Method Investment, Ownership Percentage												49.00%		49.00%
Business Acquisition, Cost of Acquired Entity, Cash Paid		$ 189,163,000			$ 4,600,000	$ 115,800,000	$ 2,300,000										$ 24,000,000			$ 3,552,000	[1]				$ 1,800,000	$ 20,000		$ 5,000				$ 118,118,000	[2]			$ 3,349,000	[3]	$ 40,700,000
Business Acquisition, Contingent Consideration, Potential Cash Payment																	15,000,000			1,500,000															800,000
Joint Venture Contract Value																							67.3
Joint Venture Contract, Miles of Pipeline (in Miles)																							135
Number of Joint Ventures Acquired																												4										2
Business Acquisition, Cost of Acquired Entity, Purchase Price						115,800,000
Payments for Previous Acquisition																													500,000	1,800,000	2,300,000			1,100,000
Business Acquisition, Contingent Consideration, at Fair Value		17,034,000						100,000	700,000							6,000,000	14,760,000			1,454,000	[1]												[2]		300,000	820,000	[3]
Line of Credit Facility, Increase, Additional Borrowings	26,000,000																																					18,000,000
Business Combination, Acquisition Related Costs		3,124,000	6,372,000																								900,000													2,200,000	6,400,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low																																									0
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High																																									17,300,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability		$ 10,019,000	$ 1,700,000	$ 1,700,000												$ 8,200,000		$ 1,000,000	$ 1,500,000																$ 300,000				$ 600,000

[1] Includes the cash purchase price at closing of $4.6 million plus a final working capital adjustment of $1.0 million, which was paid by the former Hockway shareholders to the Company in the first quarter of 2012.

[2] Includes the cash purchase price at closing of $115.8 million plus a final working capital adjustment to the sellers of $2.3 million, of which $1.8 million was paid in 2011 and $0.5 million was paid in 2012.

[3] Includes the cash purchase price at closing of $2.3 million and an additional $1.1 million payment to the sellers during the first quarter of 2012 based on a preliminary working capital adjustment.