Segment Information (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue recognition
Increase (decrease) in operating income	$ 19,215	$ 26,905	$ 53,222	$ 84,790
Increase (decrease) in net income	12,216	18,405	36,765	62,421
Increase (decrease) in net income per common share (in dollars per share)	$ 0.46	$ 0.69	$ 1.37	$ 2.33
Change in estimated total costs | Adjustment
Revenue recognition
Increase (decrease) in operating income	(4,800)	1,900	(3,800)	(5,500)
Increase (decrease) in net income	$ (2,000)	$ 900	$ (300)	$ (4,400)
Increase (decrease) in net income per common share (in dollars per share)	$ (0.07)	$ 0.03	$ (0.01)	$ (0.16)