Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Revenues	$ 310,998	$ 221,436	$ 537,215	$ 431,044
Cost of revenues	276,848	199,103	477,589	386,467
Gross profit	34,150	22,333	59,626	44,577
Selling, general and administrative expenses	19,333	13,561	34,047	27,881
Operating income	14,817	8,772	25,579	16,696
Other income (expense):
Interest expense	(351)	(217)	(574)	(400)
Interest income	8	12	13	20
Other	(68)	(7)	(156)	50
Income before income tax expense	14,406	8,560	24,862	16,366
Provision for federal, state and foreign income taxes	4,095	3,124	7,999	6,246
Net income	10,311	5,436	16,863	10,120
Net Income (Loss) Attributable to Noncontrolling Interest	5	0	5	0
Net income	$ 10,306	$ 5,436	$ 16,858	$ 10,120
Basic earnings per common share (US$ per share)	$ 0.39	$ 0.21	$ 0.64	$ 0.39
Diluted earnings per common share (US$ per share)	$ 0.38	$ 0.21	$ 0.63	$ 0.39
Weighted average common shares outstanding:
Basic (shares)	26,245	25,939	26,180	25,863
Diluted (shares)	26,884	26,204	26,772	26,172