Derivative Financial Instruments - Schedule of Derivatives, Notional Amounts Outstanding (Details) $ in Thousands	Jun. 30, 2015 USD ($) MMBTU bbl $ / bbl $ / MMBTU	Sep. 30, 2014 MMBTU $ / MMBTU
NYMEX WTI Swaps | Crude Oil | July-December 2015
Derivative [Line Items]
Volumes | bbl	282,522
Average Price	79.51
NYMEX WTI Swaps | Crude Oil | July-December 2015 | Minimum
Derivative [Line Items]
Price Range	52.00
NYMEX WTI Swaps | Crude Oil | July-December 2015 | Maximum
Derivative [Line Items]
Price Range	99.85
NYMEX WTI Swaps | Crude Oil | 2016
Derivative [Line Items]
Volumes | bbl	228,600
Average Price	87.94
NYMEX WTI Swaps | Crude Oil | 2016 | Minimum
Derivative [Line Items]
Price Range	86.30
NYMEX WTI Swaps | Crude Oil | 2016 | Maximum
Derivative [Line Items]
Price Range	99.85
NYMEX WTI Swaps | Crude Oil | 2017
Derivative [Line Items]
Volumes | bbl	182,500
Average Price	84.75
NYMEX WTI Swaps | Crude Oil | 2017 | Minimum
Derivative [Line Items]
Price Range	84.75
Midland-to-Cushing Differential Swaps [Member] | Crude Oil | July-December 2015
Derivative [Line Items]
Volumes | bbl	1,656,000
Average Price	(1.78)
Midland-to-Cushing Differential Swaps [Member] | Crude Oil | July-December 2015 | Minimum
Derivative [Line Items]
Price Range	(1.75)
Midland-to-Cushing Differential Swaps [Member] | Crude Oil | July-December 2015 | Maximum
Derivative [Line Items]
Price Range	(1.90)
Midland-to-Cushing Differential Swaps [Member] | Crude Oil | 2016
Derivative [Line Items]
Volumes | bbl	2,928,000
Average Price	(1.60)
Midland-to-Cushing Differential Swaps [Member] | Crude Oil | 2016 | Minimum
Derivative [Line Items]
Price Range	(1.50)
Midland-to-Cushing Differential Swaps [Member] | Crude Oil | 2016 | Maximum
Derivative [Line Items]
Price Range	(1.75)
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | July-December 2015
Derivative [Line Items]
Volumes | bbl	673,440
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | July-December 2015 | Put option | Short
Derivative [Line Items]
Average Strike Price	64.78
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | July-December 2015 | Put option | Long
Derivative [Line Items]
Average Strike Price	89.78
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | July-December 2015 | Call option | Short
Derivative [Line Items]
Average Strike Price	110.57
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | 2016
Derivative [Line Items]
Volumes | bbl	621,300
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | 2016 | Put option | Short
Derivative [Line Items]
Average Strike Price	63.37
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | 2016 | Put option | Long
Derivative [Line Items]
Average Strike Price	88.37
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | 2016 | Call option | Short
Derivative [Line Items]
Average Strike Price	106.40
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | 2017
Derivative [Line Items]
Volumes | bbl	72,400
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | 2017 | Put option | Short
Derivative [Line Items]
Average Strike Price	60.00
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | 2017 | Put option | Long
Derivative [Line Items]
Average Strike Price	85.00
NYMEX WTI Derivative Three-Way Collar Contracts | Crude Oil | 2017 | Call option | Short
Derivative [Line Items]
Average Strike Price	104.20
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2016
Derivative [Line Items]
Volumes | bbl	183,000
Average Price	91.70
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2016 | Put option | Short
Derivative [Line Items]
Average Strike Price	82.00
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2016 | Put option | Long
Derivative [Line Items]
Average Strike Price	57.00
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2017
Derivative [Line Items]
Volumes | bbl	182,500
Average Price	90.85
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2017 | Put option | Short
Derivative [Line Items]
Average Strike Price	82.00
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2017 | Put option | Long
Derivative [Line Items]
Average Strike Price	57.00
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2018
Derivative [Line Items]
Volumes | bbl	127,750
Average Price	90.50
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2018 | Put option | Short
Derivative [Line Items]
Average Strike Price	82.00
NYMEX WTI Enhanced Swap Contracts 1 | Crude Oil | 2018 | Put option | Long
Derivative [Line Items]
Average Strike Price	57.00
NYMEX WTI Enhanced Swap Contracts 2 | Crude Oil | July-December 2015
Derivative [Line Items]
Volumes | bbl	506,000
Average Price	93.98
NYMEX WTI Enhanced Swap Contracts 2 | Crude Oil | July-December 2015 | Put option | Short
Derivative [Line Items]
Average Strike Price	77.73
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | July-December 2015
Derivative [Line Items]
Volumes | MMBTU	11,706,400
Average Price | $ / MMBTU	4.13
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | July-December 2015 | Minimum
Derivative [Line Items]
Price Range | $ / MMBTU	3.11
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | July-December 2015 | Maximum
Derivative [Line Items]
Price Range | $ / MMBTU	5.82
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2016
Derivative [Line Items]
Volumes | MMBTU	23,019,200
Average Price | $ / MMBTU	3.43
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2016 | Minimum
Derivative [Line Items]
Price Range | $ / MMBTU	3.32
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2016 | Maximum
Derivative [Line Items]
Price Range | $ / MMBTU	5.30
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2017
Derivative [Line Items]
Volumes | MMBTU	21,600,000
Average Price | $ / MMBTU	3.37
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2017 | Minimum
Derivative [Line Items]
Price Range | $ / MMBTU	3.32
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2017 | Maximum
Derivative [Line Items]
Price Range | $ / MMBTU	3.39
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2018
Derivative [Line Items]
Volumes | MMBTU	21,600,000
Average Price | $ / MMBTU	3.37
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2018 | Minimum
Derivative [Line Items]
Price Range | $ / MMBTU	3.32
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2018 | Maximum
Derivative [Line Items]
Price Range | $ / MMBTU	3.39
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2019
Derivative [Line Items]
Volumes | MMBTU	19,800,000
Average Price | $ / MMBTU	3.38
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2019 | Minimum
Derivative [Line Items]
Price Range | $ / MMBTU	3.38
NYMEX Henry Hub, Waha, ANR-OK and CIG-Rockies Swaps | Natural gas | 2019 | Maximum
Derivative [Line Items]
Price Range | $ / MMBTU	3.39
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | July-December 2015
Derivative [Line Items]
Volumes | MMBTU	4,020,000
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | July-December 2015 | Put option | Short
Derivative [Line Items]
Average Strike Price | $ / MMBTU	3.66
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | July-December 2015 | Put option | Long
Derivative [Line Items]
Average Strike Price | $ / MMBTU	4.21
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | July-December 2015 | Call option | Short
Derivative [Line Items]
Average Strike Price | $ / MMBTU	5.01
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | 2016
Derivative [Line Items]
Volumes | MMBTU	5,580,000
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | 2016 | Put option | Short
Derivative [Line Items]
Average Strike Price | $ / MMBTU	3.75
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | 2016 | Put option | Long
Derivative [Line Items]
Average Strike Price | $ / MMBTU	4.25
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | 2016 | Call option | Short
Derivative [Line Items]
Average Strike Price | $ / MMBTU	5.08
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | 2017
Derivative [Line Items]
Volumes | MMBTU	5,040,000
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | 2017 | Put option | Short
Derivative [Line Items]
Average Strike Price | $ / MMBTU	3.75
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | 2017 | Put option | Long
Derivative [Line Items]
Average Strike Price | $ / MMBTU	4.25
NYMEX Henry Hub Derivative Three-Way Collar Contracts | Natural gas | 2017 | Call option | Short
Derivative [Line Items]
Average Strike Price | $ / MMBTU	5.53
Henry Hub NYMEX to Northwest Pipeline Natural Gas Differential Swaps | Natural gas | July-December 2015
Derivative [Line Items]
Volumes | MMBTU		6,000,000
Average Price | $ / MMBTU		(0.13)
Henry Hub NYMEX to NGPL Midcon Natural Gas Differential Swaps [Member] | Natural gas | July-December 2015
Derivative [Line Items]
Volumes | MMBTU		240,000
Average Price | $ / MMBTU		(0.15)
Interest rate swaps | Libor Swap All Tranches [Member]
Derivative [Line Items]
Estimated Fair Market Value | $	$ (985)
Interest rate swaps | Libor Swap Tranche 1
Derivative [Line Items]
Notional Amount | $	$ 29,000
Fixed Rate	3.07%
Estimated Fair Market Value | $	$ (277)
Interest rate swaps | Libor Swap Tranche 2
Derivative [Line Items]
Notional Amount | $	$ 13,000
Fixed Rate	3.112%
Estimated Fair Market Value | $	$ (160)
Interest rate swaps | Libor Swap Tranche 3
Derivative [Line Items]
Notional Amount | $	$ 12,000
Fixed Rate	3.1312%
Estimated Fair Market Value | $	$ (149)
Interest rate swaps | Libor Swap Tranche 4
Derivative [Line Items]
Notional Amount | $	$ 50,000
Fixed Rate	2.50%
Estimated Fair Market Value | $	$ (399)
Henry Hub NYMEX to California SoCal NGI Natural Gas Differential Swaps [Member] | Natural gas | July-December 2015
Derivative [Line Items]
Volumes | MMBTU		120,000
Average Price | $ / MMBTU		0.19
Henry Hub NYMEX to San Juan Basin Natural Gas Differential Swaps [Member] | Natural gas | July-December 2015
Derivative [Line Items]
Volumes | MMBTU		240,000
Average Price | $ / MMBTU		(0.12)
Henry Hub NYMEX to West Texas WAHA Natural Gas Differential Swaps [Member] | Natural gas | July-December 2015
Derivative [Line Items]
Volumes | MMBTU		3,000,000
Average Price | $ / MMBTU		(0.10)