Note 5 - Long-Term Debt and Credit Facility (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Debt Instrument, Face Amount	$ 50.0
Line of Credit Facility, Maximum Borrowing Capacity	65.0
Debt, Weighted Average Interest Rate	2.20%
Line of Credit Facility, Increase, Additional Borrowings	25.0
Senior Notes		65.0
Unsecured Debt	27.5	32.5
Line of Credit Facility, Amount Outstanding	25.0
Other Loans Payable	1.5	3.0
Due from Joint Ventures	8.0
Other Long-term Debt	4.4	4.2
Estimated Make Whole Payment	6.0
Letters of Credit Outstanding, Amount	19.3
Long-term Debt, Fair Value	130.2	106.0
Original Amount [Member]
Debt Instrument, Face Amount	50.0
Second Amendment [Member]
Line of Credit Facility, Commitment Fee Percentage	0.125%
Line of Credit Facility, Commitment Fee Amount	0.1
Line Of Credit Facility Ability To Increase Borrowing Committment	40.0
Prior ToThe Second Amendment [Member]
Line Of Credit Facility Ability To Increase Borrowing Committment	25.0
Facility Reduced Interest RateI Federal Funds Rate Plus [Member]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Facility Reduced Interest RateI Libor Plus [Member]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Facility Reduced Interest RateI Margin Range Start [Member]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Facility Reduced Interest RateI Margin Range End [Member]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Facility Reduced Interest Rate IiMargin Range Start [Member]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Facility Reduced Interest Rate IiMargin Range End [Member]
Debt Instrument, Basis Spread on Variable Rate	2.50%
Current Senior Notes [Member]
Senior Notes	65.0
Debt Instrument, Interest Rate, Stated Percentage	6.54%
Insurance Carriers Collateral [Member]
Letters of Credit Outstanding, Amount	12.5
Work Performance Obligations [Member]
Letters of Credit Outstanding, Amount	1.1
Working Capital Needs OfInsituform India [Member]
Letters of Credit Outstanding, Amount	2.4
International Trade Transaction Support [Member]
Letters of Credit Outstanding, Amount	$ 3.3