Long-Term Debt (Credit Facility Narrative) (Details) (Revolving Credit Facility [Member], USD $)	9 Months Ended			0 Months Ended
	Jun. 30, 2013 2011 Revolving Credit Facility [Member]	Jun. 30, 2013 2011 Revolving Credit Facility [Member] Eurodollar [Member]	Jul. 25, 2013 2011 Revolving Credit Facility [Member] Subsequent Event [Member]	Jul. 25, 2013 Incremental Credit Facility [Member] Subsequent Event [Member] Eurodollar [Member]	Jul. 25, 2013 Incremental Credit Facility [Member] Subsequent Event [Member] Eurodollar [Member] Minimum [Member]	Jul. 25, 2013 Incremental Credit Facility [Member] Subsequent Event [Member] Eurodollar [Member] Maximum [Member]
Line of Credit Facility [Line Items]
Outstanding credit facility	$ 680,000,000
Revolving credit facility, term	5 years
Maximum borrowing capacity	750,000,000		1,100,000,000
Credit facility variable rate		Eurodollar		Eurodollar
Credit facility basis spread on variable rate		2.50%			2.00%	2.25%
Scheduled commitment reductions			200,000,000
Amount of accordian feature exercised			350,000,000
Amount of accordian feature remaining			200,000,000
Maximum borrowing capacity, including accordian feature	$ 1,300,000,000