Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues	$ 282,911	$ 312,655	$ 552,821	$ 654,436
Cost of revenues	256,208	284,443	497,227	593,946
Gross profit	26,703	28,212	55,594	60,490
Selling, general and administrative expenses	21,529	19,975	43,099	37,952
Operating income	5,174	8,237	12,495	22,538
Other income (expense):
Interest expense	(819)	(497)	(1,437)	(740)
Interest income	65	26	104	38
Other	(135)	47	14	54
Income before income tax expense	4,285	7,813	11,176	21,890
Provision for federal, state and foreign income taxes	(247)	2,563	2,820	7,298
Net income	$ 4,532	$ 5,250	$ 8,356	$ 14,592
Basic earnings (loss) per common share (US$ per share)	$ 0.17	$ 0.20	$ 0.31	$ 0.55
Diluted earnings (loss) per common share (US$ per share)	$ 0.17	$ 0.20	$ 0.31	$ 0.54
Weighted average common shares outstanding:
Basic (shares)	26,771	26,553	26,713	26,470
Diluted (shares)	27,078	26,832	26,933	26,842