Note 8 - Segment Reporting (Details) - Financial Information by Segment (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenues:
Revenues	$ 306,234	$ 225,976
Gross profit:
Gross profit	61,063	48,137
Operating income (loss):
Operating income (loss)	9,134	6,818
Energy And Mining [Member]
Revenues:
Revenues	183,910	108,690
Gross profit:
Gross profit	35,509	24,266
Operating income (loss):
Operating income (loss)	7,676	5,451
Water and Wastewater [Member]
Revenues:
Revenues	106,133	103,796
Gross profit:
Gross profit	20,102	19,161
Operating income (loss):
Operating income (loss)	3,019	2,562
Commercial And Structural [Member]
Revenues:
Revenues	16,191	13,490
Gross profit:
Gross profit	5,452	4,710
Operating income (loss):
Operating income (loss)	$ (1,561)	$ (1,195)