Note 9 - Segment Reporting (Details) - Financial Information by Segment (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues:
Revenues	$ 350,138	$ 307,665	$ 979,240	$ 775,741
Gross profit:
Gross profit	63,939	69,411	196,920	176,116
Operating income (loss):
Operating income (loss)	(13,934)	22,032	15,819	44,673
Energy And Mining [Member]
Revenues:
Revenues	197,510	168,708	557,028	385,991
Gross profit:
Gross profit	29,380	37,118	100,856	87,678
Operating income (loss):
Operating income (loss)	(9,757)	12,874	5,661	24,481
Water and Wastewater [Member]
Revenues:
Revenues	135,649	122,149	371,493	341,680
Gross profit:
Gross profit	26,719	26,473	76,078	71,210
Operating income (loss):
Operating income (loss)	(5,450)	10,071	10,224	21,672
Commercial And Structural [Member]
Revenues:
Revenues	16,979	16,808	50,719	48,070
Gross profit:
Gross profit	7,840	5,820	19,986	17,228
Operating income (loss):
Operating income (loss)	$ 1,273	$ (913)	$ (66)	$ (1,480)