Earnings Per Common Share - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Net Income
Net income	$ 39,081	$ 46,218
Stock options	0	0
Restricted stock and performance units	0	0
Diluted earnings per share	$ 39,081	$ 46,218
Shares
Basic earnings per share (in shares)	64,765	64,405
Stock options (in shares)	0	99
Restricted stock (in shares)	156	511
Diluted earnings per share (in shares)	64,921	65,015
Per Share Amount
Basic earnings per share (in dollars per share)	$ 0.60	$ 0.72
Stock options (in dollars per share)	0.00	0.00
Restricted stock (in dollars per share)	0.00	(0.01)
Diluted earnings per share (in dollars per share)	$ 0.60	$ 0.71
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding stock options, excluded in the calculation of earnings per share	1,584	600