DEBT (Details) (USD $)			3 Months Ended		12 Months Ended							12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012 Replace collateral trusts Trust	Sep. 30, 2013 Issued to support international operations LetterOfCredit	Sep. 30, 2013 Unsecured revolving credit facility mature May 25, 2017	Sep. 30, 2013 Unsecured revolving credit facility mature May 25, 2017 Maximum	Sep. 30, 2013 Unsecured revolving credit facility mature May 25, 2017 Minimum	Sep. 30, 2013 Unsecured revolving credit facility mature May 25, 2017 Letter of credit LetterOfCredit	Sep. 30, 2013 Unsecured revolving credit facility mature May 25, 2017 Letter of credit Subsequent Event	Sep. 30, 2013 Series D, due August 15, 2014, 6.56%	Sep. 30, 2012 Series D, due August 15, 2014, 6.56%	Sep. 30, 2013 Series D, due August 15, 2014, 6.56% Maximum	Sep. 30, 2013 Unsecured senior notes issued July 21, 2009	Sep. 30, 2013 Unsecured senior notes issued July 21, 2009 Maximum	Sep. 30, 2013 Unsecured senior notes issued July 21, 2009 Minimum	Sep. 30, 2012 Due July 21, 2013, 6.10%	Sep. 30, 2013 Due July 21, 2014, 6.10%	Sep. 30, 2012 Due July 21, 2014, 6.10%	Sep. 30, 2013 Due July 21, 2015, 6.10%	Sep. 30, 2012 Due July 21, 2015, 6.10%	Sep. 30, 2013 Due July 21, 2016, 6.10%	Sep. 30, 2012 Due July 21, 2016, 6.10%
Debt
Debt outstanding	$ 195,000,000	$ 235,000,000								$ 75,000,000	$ 75,000,000		$ 120,000,000			$ 40,000,000	$ 40,000,000	$ 40,000,000	$ 40,000,000	$ 40,000,000	$ 40,000,000	$ 40,000,000
Less long-term debt due within one year	115,000,000	40,000,000
Long-term debt	80,000,000	195,000,000
Long-term debt stated interest rate percentage										6.56%	6.56%		6.10%			6.10%	6.10%	6.10%	6.10%	6.10%	6.10%	6.10%
Ratio of debt to total capitalization (as a percent)												55.00%
Annual principal repayments													40,000,000
Funded leverage ratio (as a percent)						50.00%								55.00%
Interest coverage ratio							3.00								2.50
Borrowing amount					300,000,000
Available borrowing capacity to use for letters of credit								100,000,000
Base rate for the variable rate					LIBOR	LIBOR	LIBOR
LIBOR spread on borrowings (as a percent)					1.125%	1.75%	1.125%
Commitment fee (as a percent)					0.15%	0.35%	0.15%
Borrowing amount outstanding					0
Number of letters of credit outstanding				2				2
Letters of credit outstanding/issued				12,000,000				27,200,000	3,500,000
Number of collateral trusts terminated			2
Proceeds from termination of collateral trusts			26,100,000
Available borrowing capacity excluding letters of credit transaction					$ 272,800,000				$ 269,300,000