Quarterly Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Quarterly Data (unaudited)
Net revenues	$ 107,523	$ 101,255	$ 102,511	$ 95,070	$ 117,001	$ 121,270	$ 138,688	$ 110,676	$ 406,359	$ 487,635	$ 455,410
Gross profit	13,322	13,265	8,905	12,088	21,405	24,151	27,837	20,271	47,580	93,664	47,298
Net income - Basic	$ 3,162	$ 2,792	$ (1,162)	$ 228	$ 5,784	$ 6,602	$ 11,719	$ 6,381	$ 5,020	$ 30,486	$ 3,751
Net income (loss) per share:
Basic (in dollars per share)	$ 0.25	$ 0.22	$ (0.09)	$ 0.02	$ 0.46	$ 0.53	$ 0.94	$ 0.51	$ 0.40	$ 2.45	$ 0.30
Diluted (in dollars per share)	$ 0.25	$ 0.22	$ (0.09)	$ 0.02	$ 0.46	$ 0.53	$ 0.94	$ 0.51	$ 0.40	$ 2.45	$ 0.30