Share-Based Payments (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2014
Share-Based Payments
Accelerated expense related to certain retirement eligible employees (in dollars)			$ 4,800,000	$ 5,300,000
Share-based compensation expense (in dollars)	2,840,000	3,268,000	10,600,000	11,790,000
Income tax benefit related to share-based compensation expense (in dollars)	1,077,000	1,166,000	3,995,000	4,347,000
Stock Option Awards
Share-Based Payments
Vesting period			4 years
Stock Options, Number of Outstanding Options
Outstanding at the beginning of the period (in shares)			8,983		8,983
Granted (in shares)			1,166	1,500
Exercised (in shares)			(4,426)
Forfeited or expired (in shares)			(207)
Outstanding at the end of the period (in shares)	5,516		5,516
Exercisable at the end of the period (in shares)	2,244		2,244
Stock Options, Additional Information
Outstanding at the beginning of the period (in dollars per share)			$ 15.93		$ 15.93
Granted (in dollars per share)			$ 29.23
Exercised (in dollars per share)			$ 11.73
Forfeited or expired (in dollars per share)			$ 25.41
Outstanding at the end of the period (in dollars per share)	$ 21.75		$ 21.75
Exercisable at the end of the period (in dollars per share)	$ 15.83		$ 15.83
Outstanding at the beginning of the period			7 years 2 months 12 days		6 years 2 months 12 days
Outstanding at the end of the period			7 years 2 months 12 days		6 years 2 months 12 days
Exercisable at the end of the period			5 years 7 months 6 days
Outstanding at the beginning of the period (in dollars)			102,751,000		102,751,000
Outstanding at the end of the period (in dollars)	69,586,000		69,586,000
Exercisable at the end of the period (in dollars)	$ 41,606,000		$ 41,606,000
Stock Option Awards | Maximum
Share-Based Payments
Term of stock options			10 years