SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Schedule of Revenue by Major Customers) (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015	[1]	Dec. 31, 2014	[1]	Sep. 30, 2014	[1]	Jun. 30, 2014	[1]	Mar. 31, 2014	[1]	Dec. 31, 2013	[1]	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Revenue, Major Customer [Line Items]
Revenues from significant customers	$ 363,176		$ 330,562		$ 350,387		$ 351,726		$ 323,373		$ 292,777		$ 273,097		$ 284,706		$ 1,395,851	$ 1,173,953	$ 1,063,663
Noble Energy Inc. [Member]
Revenue, Major Customer [Line Items]
Revenues from significant customers																	227,682	169,851	153,615
Shell Offshore Inc. [Member]
Revenue, Major Customer [Line Items]
Revenues from significant customers																	201,190	179,763	28,349
Woodside Energy Ltd. [Member]
Revenue, Major Customer [Line Items]
Revenues from significant customers																	166,796	68,484	75,160
Chevron Australia Pty. Ltd. [Member]
Revenue, Major Customer [Line Items]
Revenues from significant customers																	156,099	175,334	197,242
Kosmos Energy Ghana Inc. [Member]
Revenue, Major Customer [Line Items]
Revenues from significant customers																	142,701	12,933	0
Apache Energy Ltd. [Member]
Revenue, Major Customer [Line Items]
Revenues from significant customers																	39,233	209,871	159,369
Hess Corporation [Member]
Revenue, Major Customer [Line Items]
Revenues from significant customers																	$ 0	$ 0	$ 154,973

[1] The sum of the individual quarterly earnings per common share amounts may not agree with year-to-date earnings per common share as each quarterly computation is based on the weighted-average number of common shares outstanding during that period.