Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net Income Available for Common Stock	$ 86,591	$ 102,660
Other Comprehensive Income (Loss), Before Tax:
Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period	495
Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period		44,518
Reclassification Adjustment for Realized (Gains) Losses on Derivative Financial Instruments in Net Income	(7,352)
Reclassification Adjustment for Realized (Gains) Losses on Derivative Financial Instruments in Net Income		20,517
Cumulative Effect of Adoption of Authoritative Guidance for Hedging	1,313	0
Reclassification Adjustment for the Cumulative Effect of Adoption of Authoritative Guidance for Financial Assets and Liabilities to Earnings Reinvested in the Business	0	(11,738)
Other Comprehensive Income (Loss), Before Tax	(5,544)	53,297
Income Tax Expense (Benefit) Related to Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period	119
Income Tax Expense (Benefit) Related to Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period		12,744
Reclassification Adjustment for Income Tax Benefit (Expense) on Realized Losses (Gains) from Derivative Financial Instruments in Net Income	(2,031)
Reclassification Adjustment for Income Tax Benefit (Expense) on Realized Losses (Gains) from Derivative Financial Instruments in Net Income		5,794
Income Tax Benefit (Expense) on Cumulative Effect of Adoption of Authoritative Guidance for Hedging	363	0
Reclassification Adjustment for Income Tax Benefit (Expense) on the Cumulative Effect of Adoption of Authoritative Guidance for Financial Assets and Liabilities to Earnings Reinvested in the Business	0	(4,301)
Income Taxes – Net	(1,549)	14,237
Other Comprehensive Income (Loss)	(3,995)	39,060
Comprehensive Income	$ 82,596	$ 141,720