Condensed Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Net revenue	$ 372,345	$ 353,963	$ 1,094,138	$ 1,045,393
Cost of revenue	292,498	274,569	861,992	811,385
Operating expenses:
General and administrative	40,413	42,988	123,992	132,614
Depreciation and amortization	19,161	18,634	56,146	54,952
Total operating expenses	59,574	61,622	180,138	187,566
Income from operations	20,273	17,772	52,008	46,442
Other income (expense):
Other income (expense), net	(149)	(140)	762	(1,098)
Interest expense	(8,339)	(8,493)	(25,117)	(25,530)
Income from continuing operations before income taxes	11,785	9,139	27,653	19,814
Provision for income taxes	4,424	4,296	10,634	13,032
Income from continuing operations	7,361	4,843	17,019	6,782
Loss from discontinued operations, net of tax	0	(27)	0	(255)
Net income	$ 7,361	$ 4,816	$ 17,019	$ 6,527
Income per common share, basic
Income from continuing operations, basic (in dollars per share)	$ 0.20	$ 0.13	$ 0.46	$ 0.18
Loss from discontinued operations, net of tax (in dollars per share)	0.00	0.00	0.00	0.00
Net income per share, basic (in dollars per share)	0.20	0.13	0.46	0.18
Income per common share, diluted
Income from continuing operations, diluted (in dollars per share)	0.20	0.13	0.45	0.18
Loss from discontinued operations, net of tax (in dollars per share)	0.00	0.00	0.00	0.00
Net income per share, diluted (in dollars per share)	$ 0.20	$ 0.13	$ 0.45	$ 0.18
Weighted average number of common shares outstanding, basic (in shares)	37,323,458	37,108,486	37,278,760	37,101,968
Weighted average number of common shares outstanding, diluted (in shares)	37,495,488	37,252,344	37,413,264	37,247,784