Supplemental Condensed Consolidating Financial Information (Supplemental Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2014
Cash and cash equivalents		$ 217	$ 23	$ 5,601
Trade accounts receivable - net	$ 55,146	71,323
Derivative financial instruments	1,970	888
Restricted cash	6,025	6,024
Prepaid expenses	1,523	1,831
Total current assets	64,664	80,283
Net property and equipment	1,053,954	1,415,025
Goodwill			0
Restricted cash	21,008
Other assets	947	1,039
Total assets	1,140,573	1,496,347
Accounts payable	42,797	24,548
Accrued expenses	71,550	95,981
Asset retirement obligations	15,839	38,056
Derivative financial instruments		1,057
Due to EGC	190,401	170,728
Current maturities of long-term debt	1,684	3,364
Total current liabilities	322,271	333,734
Long-term debt, less current maturities	686,018	689,459
Promissory note payable to EGC	325,000	325,000
Asset retirement obligations	196,004	202,306
Total Liabilities	$ 1,529,293	$ 1,550,499
Preferred stock
Common stock
Additional paid-in capital	$ 1,599,341	$ 1,599,341
Accumulated deficit	(1,988,061)	(1,653,493)
Total stockholders' equity	(388,720)	(54,152)
Total liabilities and stockholder's deficit	1,140,573	1,496,347
Parent Company [Member]
Cash and cash equivalents		217	$ 23	$ 5,601
Trade accounts receivable - net	55,146	71,406
Derivative financial instruments	1,970	888
Restricted cash	6,025	6,024
Prepaid expenses	1,523	1,831
Total current assets	64,664	80,366
Net property and equipment	1,051,005	1,412,076
Investment in affiliates	130,705	130,705
Restricted cash	21,008
Other assets	947	1,039
Total assets	1,268,329	1,624,186
Accounts payable	42,797	24,217
Intercompany payables	127,756	128,170
Accrued expenses	71,550	95,981
Asset retirement obligations	15,839	38,056
Derivative financial instruments		1,057
Due to EGC	190,401	170,728
Current maturities of long-term debt	1,684	3,364
Total current liabilities	450,027	461,573
Long-term debt, less current maturities	686,018	689,459
Promissory note payable to EGC	325,000	325,000
Asset retirement obligations	196,004	202,306
Total Liabilities	$ 1,657,049	$ 1,678,338
Preferred stock
Common stock
Additional paid-in capital	$ 1,599,341	$ 1,599,341
Accumulated deficit	(1,988,061)	(1,653,493)
Total stockholders' equity	(388,720)	(54,152)
Total liabilities and stockholder's deficit	1,268,329	1,624,186
Guarantor Subsidiaries [Member]
Intercompany receivables	127,756	128,170
Total current assets	127,756	128,170
Net property and equipment	2,949	2,949
Total assets	$ 130,705	131,119
Accounts payable		414
Total current liabilities		414
Total Liabilities		$ 414
Preferred stock
Common stock
Additional paid-in capital	$ 85,479	$ 85,479
Accumulated deficit	45,226	45,226
Total stockholders' equity	130,705	130,705
Total liabilities and stockholder's deficit	130,705	131,119
Consolidation, Eliminations [Member]
Trade accounts receivable - net		(83)
Intercompany receivables	(127,756)	(128,170)
Total current assets	(127,756)	(128,253)
Investment in affiliates	(130,705)	(130,705)
Total assets	(258,461)	(258,958)
Accounts payable		(83)
Intercompany payables	(127,756)	(128,170)
Total current liabilities	(127,756)	(128,253)
Total Liabilities	$ (127,756)	$ (128,253)
Preferred stock
Common stock
Additional paid-in capital	$ (85,479)	$ (85,479)
Accumulated deficit	(45,226)	(45,226)
Total stockholders' equity	(130,705)	(130,705)
Total liabilities and stockholder's deficit	$ (258,461)	$ (258,958)