Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net Income (Loss) Available for Common Stock	$ 88,908	$ (189,109)
Other Comprehensive Income (Loss), Before Tax:
Unrealized Gain (Loss) on Securities Available for Sale Arising During the Period	(883)	(638)
Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period	(52,501)	65,372
Reclassification Adjustment for Realized (Gains) Losses on Securities Available for Sale in Net Income	(741)	0
Reclassification Adjustment for Realized (Gains) Losses on Derivative Financial Instruments in Net Income	(30,717)	(57,170)
Other Comprehensive Income (Loss), Before Tax	(84,842)	7,564
Income Tax Expense (Benefit) Related to Unrealized Gain (Loss) on Securities Available for Sale Arising During the Period	(344)	(191)
Income Tax Expense (Benefit) Related to Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period	(22,052)	20,676
Reclassification Adjustment for Income Tax Benefit (Expense) on Realized Losses (Gains) from Securities Available for Sale in Net Income	(273)	0
Reclassification Adjustment for Income Tax Benefit (Expense) on Realized Losses (Gains) from Derivative Financial Instruments in Net Income	(12,954)	(18,005)
Income Taxes – Net	(35,623)	2,480
Other Comprehensive Income (Loss)	(49,219)	5,084
Comprehensive Income (Loss)	$ 39,689	$ (184,025)