General (Details) $ in Thousands			1 Months Ended			3 Months Ended					9 Months Ended		12 Months Ended
	Mar. 01, 2015 USD ($)	Mar. 31, 2014 USD ($)	Jul. 31, 2015 USD ($)	Feb. 28, 2015	Dec. 31, 2014	Sep. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 plant	Feb. 28, 2014	Dec. 31, 2013
General [Line Items]
Contingent consideration payment											$ 684	$ 0
Proceeds from sale of interests in Bayou Coating, L.L.C.											0	9,065
Equity in earnings of affiliated companies						$ 0			$ 0		0	677
Proceeds from equity method investment											0	684
Loss on sale of interests in Bayou Coating, L.L.C.											0	472
Payments to purchase noncontrolling interest											$ 0	$ 617
Restructuring Plan 2014 [Member]
General [Line Items]
Number of plant closures | plant													2
Restructuring Plan 2014 [Member] | Minimum [Member]
General [Line Items]
Period of capital investments in the remaining coating facilities											1 year
Restructuring Plan 2014 [Member] | Maximum [Member]
General [Line Items]
Period of capital investments in the remaining coating facilities											2 years
CRTS [Member]
General [Line Items]
Contingent consideration payment			$ 700
Proceeds from settlement of escrow claims			1,000
CRTS [Member] | Operating Expense [Member]
General [Line Items]
Proceeds from settlement of escrow claims			200
CRTS [Member] | Other Income (Expense) [Member]
General [Line Items]
Proceeds from settlement of escrow claims			$ 800
Schultz Mechanical Contractors, Inc. [Member]
General [Line Items]
Total consideration recorded	$ 7,878
Cash payments to acquire business	6,900
Purchase price	7,100
Working capital adjustment	200
Adjustment to account for deferred consideration	$ 1,000
Ka-te [Member]
General [Line Items]
Period of trademark license					5 years
Gain (Loss) on Disposition of Business								$ 500
Video Injection - Instituform SAS [Member]
General [Line Items]
Period of trademark license				5 years
Gain (Loss) on Disposition of Business							$ 2,900
Bayou Coating [Member]
General [Line Items]
Percent of book value		49.00%								49.00%					49.00%
Percent interest by noncontrolling owners		51.00%								51.00%
Proceeds from sale of interests in Bayou Coating, L.L.C.		$ 9,100
Equity in earnings of affiliated companies										$ 1,200
Proceeds from equity method investment										$ 700
Delta Double Jointing [Member]
General [Line Items]
Percent interest by noncontrolling owners														41.00%
Percent ownership interest by parent														59.00%
Payments to purchase noncontrolling interest		$ 600
Insituform Linings Ltd. [Member] | Ka-te [Member]
General [Line Items]
Term of exclusive tube supply agreement					5 years
Insituform Linings Ltd. [Member] | Video Injection - Instituform SAS [Member]
General [Line Items]
Term of exclusive tube supply agreement				5 years