Capitalization and Short-Term Borrowings (Summary of Changes in Common Stock Equity) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Dec. 31, 2024	Dec. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		91,005,993
Beginning balance		$ 2,848,343
Net Income Available for Common Stock		44,986	$ 133,020
Dividends Declared on Common Stock		(46,671)	(45,597)
Other Comprehensive Income (Loss), Net of Tax		$ (60,677)	$ 122,441
Share Repurchases (in shares)		(393,038)
Ending balance (in shares)		90,612,955
Ending balance		$ 2,752,813
Dividends per share (in dollars per share)		$ 0.515	$ 0.495
Share Repurchase Plan
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share Repurchases (in shares)		(548,596)
Share Repurchases		$ (33,900)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		91,006,000	91,819,000
Beginning balance		$ 91,006	$ 91,819
Common stock issued under stock and benefit plans (in shares)		156,000	297,000
Common Stock Issued Under Stock and Benefit Plans		$ 156	$ 297
Ending balance (in shares)		90,613,000	92,116,000
Ending balance		$ 90,613	$ 92,116
Common Stock | Share Repurchase Plan
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share Repurchases (in shares)		(549,000)
Share Repurchases		$ (549)
Paid In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,045,487	1,040,761
Share-Based Payment Expense	[1]	4,090	4,135
Ending balance		1,039,705	1,041,226
Paid In Capital | Stock and Benefit Plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share Repurchases		(3,511)	3,670
Paid In Capital | Share Repurchase Plan
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share Repurchases		(6,361)
Earnings Reinvested in the Business
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,727,326	1,885,856
Net Income Available for Common Stock		44,986	133,020
Dividends Declared on Common Stock		(46,671)	(45,597)
Share Repurchases		(26,993)	0
Ending balance		1,698,648	1,973,279
Earnings Reinvested in the Business | Share Repurchase Plan
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share Repurchases		(26,993)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		(15,476)	(55,060)
Other Comprehensive Income (Loss), Net of Tax		(60,677)	122,441
Ending balance		$ (76,153)	$ 67,381

[1] Paid in Capital includes compensation costs associated with performance shares and/or restricted stock awards. The expense is included within Net Income Available For Common Stock, net of tax benefits.