Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net Income (Loss) Available for Common Stock	$ (147,687)	$ 16,669	$ (336,796)	$ 101,409
Other Comprehensive Income (Loss), Before Tax:
Unrealized Gain (Loss) on Securities Available for Sale Arising During the Period	(4)	265	(642)	(147)
Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period	33,768	61,165	99,139	304,994
Reclassification Adjustment for Realized (Gains) Losses on Securities Available for Sale in Net Income	(388)	0	(388)	0
Reclassification Adjustment for Realized (Gains) Losses on Derivative Financial Instruments in Net Income	(61,235)	(54,130)	(118,405)	(78,395)
Other Comprehensive Income (Loss), Before Tax	(27,859)	7,300	(20,296)	226,452
Income Tax Expense (Benefit) Related to Unrealized Gain (Loss) on Securities Available for Sale Arising During the Period	(16)	99	(207)	(61)
Income Tax Expense (Benefit) Related to Unrealized Gain (Loss) on Derivative Financial Instruments Arising During the Period	14,190	25,902	34,866	128,851
Reclassification Adjustment for Income Tax Benefit (Expense) on Realized Losses (Gains) from Securities Available for Sale in Net Income	(163)	0	(163)	0
Reclassification Adjustment for Income Tax Benefit (Expense) on Realized Losses (Gains) from Derivative Financial Instruments in Net Income	(25,600)	(22,917)	(43,606)	(33,006)
Income Taxes – Net	(11,589)	3,084	(9,110)	95,784
Other Comprehensive Income (Loss)	(16,270)	4,216	(11,186)	130,668
Comprehensive Income (Loss)	$ (163,957)	$ 20,885	$ (347,982)	$ 232,077