Earnings Per Common Share - Narrative (Details) (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
Net Income
Basic earnings per share	$ 71,925	$ 89,981	$ 228,622	$ 248,331
Stock options	0	0	0	0
Restricted stock	0	0	0	0
Diluted earnings per share	$ 71,925	$ 89,981	$ 228,622	$ 248,331
Shares
Basic earnings per share (in shares)	64,309	65,062	64,204	65,441
Stock options (in shares)	216	304	250	367
Restricted stock (in shares)	535	492	569	372
Diluted earnings per share (in shares)	65,060	65,858	65,023	66,180
Per Share Amount
Basic earnings per share (in dollars per share)	$ 1.12	$ 1.38	$ 3.56	$ 3.79
Stock options (in dollars per share)	$ 0.00	$ 0.00	$ (0.01)	$ (0.02)
Restricted stock (in dollars per share)	$ (0.01)	$ (0.01)	$ (0.03)	$ (0.02)
Diluted earnings per share (in dollars per share)	$ 1.11	$ 1.37	$ 3.52	$ 3.75
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding stock options, excluded in the calculation of earnings per share	0	283	0	283