LONG-TERM DEBT (Credit Facility Narrative) (Details) (Revolving Credit Facility [Member], USD $)	1 Months Ended	12 Months Ended						12 Months Ended		1 Months Ended
	May 31, 2011 2011 Revolving Credit Facility [Member]	Sep. 30, 2013 2011 Revolving Credit Facility [Member]		Jul. 31, 2013 2011 Revolving Credit Facility [Member]	Sep. 30, 2012 2011 Revolving Credit Facility [Member]		Sep. 30, 2013 2011 Revolving Credit Facility [Member] Maximum [Member]	Sep. 30, 2013 2011 Revolving Credit Facility [Member] Minimum [Member]	Sep. 30, 2013 2011 Revolving Credit Facility [Member] Eurodollar [Member]	Jul. 31, 2013 Incremental Credit Facility [Member]	Jul. 31, 2013 Incremental Credit Facility [Member] Eurodollar [Member]	Jul. 31, 2013 Incremental Credit Facility [Member] Eurodollar [Member] Maximum [Member]	Jul. 31, 2013 Incremental Credit Facility [Member] Eurodollar [Member] Minimum [Member]	Nov. 14, 2013 Subsequent Event [Member] 2011 Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Outstanding credit facility		$ 605,000,000
Revolving credit facility, term	5 years	5 years
Maximum borrowing capacity	750,000,000	1,100,000,000.0		1,100,000,000.0
Credit facility variable rate									Eurodollar		Eurodollar
Credit facility basis spread on variable rate									2.50%			2.25%	2.00%
Effective interest rate		3.00%	[1]		3.20%	[1]
Credit facility commitment fee (per annum)		1.00%								0.50%
Borrowings from line of credit														0
Standby letters of credit		100,000
Scheduled commitment reductions				200,000,000
Amount of accordion feature exercised				350,000,000
Amount of accordion feature remaining		200,000,000
Maximum borrowing capacity, including accordion feature		$ 1,300,000,000
Leverage ratio							4.0
Debt to capitalization ratio							0.5
Interest expense coverage ratio								3.0
Collateral maintenance percentage								150.00%

[1] After the impact of our interest rate swaps.