DEBT (Credit Facility Narrative) (Details)	6 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Aug. 06, 2015 USD ($)	Jul. 29, 2015
Line of Credit Facility [Line Items]
Credit Facility Reduction In Commitment From Raising Capital		70.00%
Senior Secured Leverage Ratio		3.00
Debt, Weighted Average Interest Rate	2.28%	2.60%	2.28%
Interest Expense, Debt		$ 52,551,000	$ 41,803,000	$ 24,903,000
Interest Costs Capitalized		$ 22,200,000	$ 30,000,000	$ 33,200,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 1,550,000,000.000
Maximum Leverage Ratio through December 2017		4.50
Maximum Leverage Ratio After December 2017		4.00
Outstanding credit facility		$ 1,030,000,000
Standby letters of credit		5,300,000
Line of Credit Facility, Remaining Borrowing Capacity		512,000,000
Collateral Maintenance						1.5
Revolving Credit Facility [Member] | Restatement Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		1,547,000,000.000
May 2018 [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		305,000,000
May 2019 [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 1,245,000,000
Minimum [Member] | Eurodollar [Member] | Revolving Credit Facility [Member] | Restatement Agreement [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.30%
Maximum [Member] | Eurodollar [Member] | Revolving Credit Facility [Member] | Restatement Agreement [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.40%