Note 17 - Subsequent Events	12 Months Ended
Dec. 31, 2019
Notes to Financial Statements
Subsequent Events [Text Block]	17. SUBSEQUENT EVENTS Sale of Insituform Australia On January 24, 2020, the Company sold its Australian CIPP contracting entity, Insituform Pacific Pty Limited (“IPPL”), to Insituform Holdings Pty Ltd, an entity affiliated with Killard Infrastructure Pty Ltd. In connection with the sale, the Company entered into an exclusive five-year tube supply agreement whereby IPPL, under its new ownership, will buy liners exclusively from the Company. IPPL is also entitled to use the Insituform^® trade name in Australia based on a trademark license granted for the same five-year time period. During the second quarter of 2019, the Company recorded an impairment charge of $5.1 million to adjust carrying value to the expected fair value less cost to sell. No additional impairment charges are expected to be recorded as the net carrying value approximated or was less than the sale price. Sale of Insituform Spain On February 13, 2020, the Company sold its Spanish CIPP contracting entity, Insituform Technologies Iberica, S.A. (“Insituform Spain”) to Lajusocrley S.L. In connection with the sale, the Company entered into a five-year tube supply agreement whereby Insituform Spain will buy liners from the Company. The buyers are also entitled to use the Insituform^® trade name in Spain based on a trademark license granted for the same five-year time period. During the fourth quarter of 2019, the Company recorded an impairment charge of $6.0 million to adjust carrying value to the expected fair value less cost to sell. No additional impairment charges are expected to be recorded as the net carrying value approximated or was less than the sale price.

Note 17 - Subsequent Events

12 Months Ended

Dec. 31, 2019

17. SUBSEQUENT EVENTS

Sale of Insituform Australia

On January 24, 2020, the Company sold its Australian CIPP contracting entity, Insituform Pacific Pty Limited (“IPPL”), to Insituform Holdings Pty Ltd, an entity affiliated with Killard Infrastructure Pty Ltd. In connection with the sale, the Company entered into an exclusive five-year tube supply agreement whereby IPPL, under its new ownership, will buy liners exclusively from the Company. IPPL is also entitled to use the Insituform^® trade name in Australia based on a trademark license granted for the same five-year time period. During the second quarter of 2019, the Company recorded an impairment charge of $5.1 million to adjust carrying value to the expected fair value less cost to sell. No additional impairment charges are expected to be recorded as the net carrying value approximated or was less than the sale price.

Sale of Insituform Spain

On February 13, 2020, the Company sold its Spanish CIPP contracting entity, Insituform Technologies Iberica, S.A. (“Insituform Spain”) to Lajusocrley S.L. In connection with the sale, the Company entered into a five-year tube supply agreement whereby Insituform Spain will buy liners from the Company. The buyers are also entitled to use the Insituform^® trade name in Spain based on a trademark license granted for the same five-year time period. During the fourth quarter of 2019, the Company recorded an impairment charge of $6.0 million to adjust carrying value to the expected fair value less cost to sell. No additional impairment charges are expected to be recorded as the net carrying value approximated or was less than the sale price.