Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Revenues	$ 221,436	$ 200,964	$ 431,044	$ 370,285
Cost of revenues	199,103	177,866	386,467	329,094
Gross profit	22,333	23,098	44,577	41,191
Selling, general and administrative expenses	13,561	11,898	27,881	23,381
Operating income	8,772	11,200	16,696	17,810
Other income (expense):
Interest expense	(217)	(166)	(400)	(443)
Interest income	12	3	20	6
Other	(7)	301	50	(375)
Income before income tax expense	8,560	11,338	16,366	16,998
Provision for federal, state and foreign income taxes	3,124	4,307	6,246	6,458
Net income	$ 5,436	$ 7,031	$ 10,120	$ 10,540
Basic earnings per common share (US$ per share)	$ 0.21	$ 0.27	$ 0.39	$ 0.40
Diluted earnings per common share (US$ per share)	$ 0.21	$ 0.27	$ 0.39	$ 0.40
Weighted average common shares outstanding:
Basic (shares)	25,939	25,819	25,863	26,110
Diluted (shares)	26,204	26,111	26,172	26,420