Quarterly Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Quarterly Data (unaudited)
Net revenues	$ 117,001	$ 121,270	$ 138,688	$ 110,676	$ 120,067	$ 126,293	$ 115,350	$ 93,700	$ 487,635	$ 455,410	$ 482,746
Gross Profit	21,405	24,151	27,837	20,271	18,923	14,061	9,064	5,250	93,664	47,298	73,626
Net income	$ 5,784	$ 6,602	$ 11,719	$ 6,381	$ 6,370	$ 2,096	$ (1,223)	$ (3,492)	$ 30,486	$ 3,751	$ 21,577
Net income (loss) per share:
Basic (in dollars per share)	$ 0.46	$ 0.53	$ 0.94	$ 0.51	$ 0.51	$ 0.17	$ (0.10)	$ (0.29)	$ 2.45	$ 0.30	$ 1.75
Diluted (in dollars per share)	$ 0.46	$ 0.53	$ 0.94	$ 0.51	$ 0.51	$ 0.17	$ (0.10)	$ (0.29)	$ 2.45	$ 0.30	$ 1.74