Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
Revenues	$ 225,970	$ 183,899	$ 657,014	$ 554,184
Cost of revenues	202,844	164,128	589,311	493,222
Gross profit	23,126	19,771	67,703	60,962
Selling, general and administrative expenses	14,695	12,356	42,576	35,737
Operating income	8,431	7,415	25,127	25,225
Other income (expense):
Interest expense	(205)	(174)	(605)	(617)
Interest income	5	12	25	18
Other	43	(55)	93	(430)
Income before income tax expense	8,274	7,198	24,640	24,196
Provision for federal, state and foreign income taxes	1,753	2,336	7,999	8,794
Net income	$ 6,521	$ 4,862	$ 16,641	$ 15,402
Basic earnings per common share (US$ per share)	$ 0.25	$ 0.19	$ 0.64	$ 0.59
Diluted earnings per common share (US$ per share)	$ 0.25	$ 0.19	$ 0.63	$ 0.58
Weighted average common shares outstanding:
Basic (shares)	26,039	25,723	25,921	25,982
Diluted (shares)	26,411	26,079	26,269	26,333