Segment Information - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Revenue recognition
Increase (decrease) in operating income	$ (2,072)	$ (9,086)	$ (6,173)	$ (17,163)
Net income (loss)	$ 461	$ 10,144	$ (2,407)	$ 4,730
Increase (decrease) in net income per common share (in dollars per share)	$ 0.02	$ 0.38	$ (0.09)	$ 0.18
Unallocated corporate expenses and other
Revenue recognition
Expense related to the development of ERP system	$ 6,000	$ 9,400	$ 14,600	$ 15,900
Increase (decrease) in operating income	(7,500)	(12,000)	(20,400)	(20,500)
Change in estimated total costs | Adjustment
Revenue recognition
Increase (decrease) in operating income	3,300	(300)	(4,600)	(2,400)
Net income (loss)	$ 2,300	$ 200	$ (2,500)	$ 1,400
Increase (decrease) in net income per common share (in dollars per share)	$ 0.09	$ 0.01	$ (0.09)	$ 0.05