Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income Available for Common Stock	$ 198,654	$ 88,908
Other Comprehensive Income (Loss), Before Tax:
Unrealized Gain (Loss) on Securities Available for Sale Arising During the Period	(44)	(883)
Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period	(5,499)	(52,501)
Reclassification Adjustment for Realized (Gains) Losses on Securities Available for Sale in Net Income	(430)	(741)
Reclassification Adjustment for Realized (Gains) Losses on Derivative Financial Instruments in Net Income	(12,548)	(30,717)
Other Comprehensive Loss, Before Tax	(18,521)	(84,842)
Income Tax Expense (Benefit) Related to Unrealized Gain (Loss) on Securities Available for Sale Arising During the Period	(65)	(344)
Income Tax Expense (Benefit) Related to Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period	(2,305)	(22,052)
Reclassification Adjustment for Income Tax Benefit (Expense) on Realized Losses (Gains) from Securities Available for Sale in Net Income	(158)	(273)
Reclassification Adjustment for Income Tax Benefit (Expense) on Realized Losses (Gains) from Derivative Financial Instruments in Net Income	(5,197)	(12,954)
Income Taxes – Net	(7,725)	(35,623)
Other Comprehensive Loss	(10,796)	(49,219)
Comprehensive Income	$ 187,858	$ 39,689