Accumulated Other Comprehensive Income Components (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	$ (47,607)
Other comprehensive income before reclassifications	79,068
Amounts reclassified from accumulated other comprehensive income	7,417
Net current-period other comprehensive income (loss)	86,485	853	(25,088)
Accumulated other comprehensive income (loss), ending balance	38,878	(47,607)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	5,661
Other comprehensive income before reclassifications	1,162
Amounts reclassified from accumulated other comprehensive income	(1,375)
Net current-period other comprehensive income (loss)	(213)
Accumulated other comprehensive income (loss), ending balance	5,448
Accumulated Net Gain (Loss) from Interest Rate Hedges [Member] [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(44,273)
Other comprehensive income before reclassifications	79,963
Amounts reclassified from accumulated other comprehensive income	2,216
Net current-period other comprehensive income (loss)	82,179
Accumulated other comprehensive income (loss), ending balance	37,906
Accumulated Net Gain (Loss) from Commodity Contracts Cash Flow Hedges [Member] [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(8,995)
Other comprehensive income before reclassifications	(2,057)
Amounts reclassified from accumulated other comprehensive income	6,576
Net current-period other comprehensive income (loss)	4,519
Accumulated other comprehensive income (loss), ending balance	$ (4,476)