Derivative Financial Instruments Derivative Financial Instruments - Oil and Gas Commodity Contracts (Details) bbl in Thousands, MMBTU in Thousands, MBbls in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2016 USD ($) MMBTU $ / MMBTU $ / bbl MBbls	Mar. 31, 2015	Mar. 31, 2016 USD ($) MMBTU $ / MMBTU $ / bbl MBbls	Mar. 31, 2015	Sep. 30, 2015 MMBTU bbl
Derivative [Line Items]
Derivative, Percentage of Production Volume Covered by Derivative Financial Instruments	20.00%	38.00%	44.00%	55.00%
Natural Gas Commodity Contract [Member]
Derivative [Line Items]
Natural Gas, Volume | MMBTU	2,750,000		2,750,000
Fair Value at March 31, 2016	$ 0.3		$ 0.3
Oil Commodity Contract [Member]
Derivative [Line Items]
Fair Value at March 31, 2016	$ 1.1		$ 1.1
Derivative, Commodity Contract, Oil Volume | MBbls	138		138
Swap [Member] | Natural Gas Commodity Contract [Member]
Derivative [Line Items]
Natural Gas, Volume | MMBTU					3,380
Swap [Member] | Oil Commodity Contract [Member]
Derivative [Line Items]
Derivative, Commodity Contract, Oil Volume | bbl					273
Swap [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Fair Value at March 31, 2016	$ 1.4		$ 1.4
Collar [Member] | Natural Gas Commodity Contract [Member] | Remainder of 2014 [Member]
Derivative [Line Items]
Natural Gas, Volume | MMBTU	2,750,000		2,750,000
Fair Value at March 31, 2016	$ 0.3		$ 0.3
Collar [Member] | Natural Gas Commodity Option Contract- Short call [Member] [Member] | Remainder of 2014 [Member]
Derivative [Line Items]
Weighted average strike price per Mmbtu/Bbl | $ / MMBTU	2.77		2.77
Collar [Member] | Natural Gas Commodity Commodity Contract- Long put [Member] | Remainder of 2014 [Member]
Derivative [Line Items]
Weighted average strike price per Mmbtu/Bbl | $ / MMBTU	2.15		2.15
Three-way collar [Member] | Natural Gas Commodity Contract [Member] | Remainder of 2014 [Member]
Derivative [Line Items]
Fair Value at March 31, 2016	$ 1.1		$ 1.1
Three-way collar [Member] | Oil Commodity Contract [Member] | Remainder of 2014 [Member]
Derivative [Line Items]
Derivative, Commodity Contract, Oil Volume | MBbls	138		138
Short put [Member] | Three-way collar [Member] | Oil Commodity Contract [Member] | Remainder of 2014 [Member]
Derivative [Line Items]
Weighted average strike price per Mmbtu/Bbl | $ / bbl	42.00		42.00
Long put [Member] | Three-way collar [Member] | Oil Commodity Contract [Member] | Remainder of 2014 [Member]
Derivative [Line Items]
Weighted average strike price per Mmbtu/Bbl | $ / bbl	56.00		56.00
Short call [Member] | Three-way collar [Member] | Oil Commodity Contract [Member] | Remainder of 2014 [Member]
Derivative [Line Items]
Weighted average strike price per Mmbtu/Bbl | $ / bbl	76.00		76.00