Quarterly Results Of Operations (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 Financial Information Disclosure [Abstract]
Revenues	$ 129,793	$ 133,207	$ 152,266	$ 149,977	$ 162,325	$ 176,733	$ 170,199	$ 152,601	$ 565,243	$ 661,858	$ 647,814
Gross profit	25,676	27,285	30,094	23,150	29,947	32,944	24,301	21,069	106,205	108,261	125,474
Net income (loss)	$ 5,508	$ 4,894	$ 5,567	$ (459)	$ 6,312	$ 7,049	$ (3,683)	$ (239)	$ 15,510	$ 9,439	$ 29,224
Earnings per share:
Basic	$ 0.48	$ 0.43	$ 0.49	$ (0.04)	$ 0.54	$ 0.60	$ (0.31)	$ (0.02)	$ 1.36	$ 0.80	$ 2.43
Diluted	$ 0.48	$ 0.43	$ 0.49	$ (0.04)	$ 0.54	$ 0.60	$ (0.31)	$ (0.02)	$ 1.36	$ 0.79	$ 2.42