Physical Delivery Contracts and Gas Derivatives (Details)	Sep. 30, 2018 USD_Bbl USD-MMBtu $ / shares
2018 [Member] | Natural Gas Swaps [Member]
Derivative agreements details:
Quantity | USD-MMBtu	870,000
Weighted Average Price	$ 3.00	[1]
2018 [Member] | Natural Gas Collars [Member]
Derivative agreements details:
Quantity | USD-MMBtu
Weighted Average Price		[1]
2018 [Member] | Oil Swaps [Member]
Derivative agreements details:
Quantity | USD_Bbl	23,000
Weighted Average Price	$ 55.09	[2]
2018 [Member] | Carbon California [Member] | Natural Gas Swaps [Member]
Derivative agreements details:
Quantity | USD-MMBtu	90,000
Weighted Average Price	$ 3.03	[1]
2018 [Member] | Carbon California [Member] | Natural Gas Collars [Member]
Derivative agreements details:
Quantity | USD-MMBtu
Weighted Average Price		[1]
2018 [Member] | Carbon California [Member] | Oil Swaps [Member] | WTI Bbl [Member]
Derivative agreements details:
Quantity | USD_Bbl	48,628
Weighted Average Price	$ 53.06	[2]
2018 [Member] | Carbon California [Member] | Oil Swaps [Member] | Brent Bbl [Member]
Derivative agreements details:
Quantity | USD_Bbl	62,792
Weighted Average Price	$ 66.46	[3]
2019 [Member] | Natural Gas Swaps [Member]
Derivative agreements details:
Quantity | USD-MMBtu	2,596,000
Weighted Average Price	$ 2.86	[1]
2019 [Member] | Natural Gas Collars [Member]
Derivative agreements details:
Quantity | USD-MMBtu	204,000
2019 [Member] | Natural Gas Collars [Member] | Minimum [Member]
Derivative agreements details:
Weighted Average Price	$ 2.60	[1]
2019 [Member] | Natural Gas Collars [Member] | Maximum [Member]
Derivative agreements details:
Weighted Average Price	$ 2.80	[1]
2019 [Member] | Oil Swaps [Member]
Derivative agreements details:
Quantity | USD_Bbl	61,900
Weighted Average Price	$ 56.05	[2]
2019 [Member] | Carbon California [Member] | Natural Gas Swaps [Member]
Derivative agreements details:
Quantity | USD-MMBtu
Weighted Average Price		[1]
2019 [Member] | Carbon California [Member] | Natural Gas Collars [Member]
Derivative agreements details:
Quantity | USD-MMBtu	360,000
2019 [Member] | Carbon California [Member] | Natural Gas Collars [Member] | Minimum [Member]
Derivative agreements details:
Weighted Average Price	$ 2.60	[1]
2019 [Member] | Carbon California [Member] | Natural Gas Collars [Member] | Maximum [Member]
Derivative agreements details:
Weighted Average Price	$ 3.03	[1]
2019 [Member] | Carbon California [Member] | Oil Swaps [Member] | WTI Bbl [Member]
Derivative agreements details:
Quantity | USD_Bbl	139,797
Weighted Average Price	$ 51.96	[2]
2019 [Member] | Carbon California [Member] | Oil Swaps [Member] | Brent Bbl [Member]
Derivative agreements details:
Quantity | USD_Bbl	141,786
Weighted Average Price	$ 66.58	[3]
2020 [Member] | Natural Gas Collars [Member]
Derivative agreements details:
Quantity | USD-MMBtu	1,018,000
2020 [Member] | Natural Gas Collars [Member] | Minimum [Member]
Derivative agreements details:
Weighted Average Price	$ 2.50	[1]
2020 [Member] | Natural Gas Collars [Member] | Maximum [Member]
Derivative agreements details:
Weighted Average Price	$ 2.70	[1]
2020 [Member] | Oil Swaps [Member]
Derivative agreements details:
Quantity | USD_Bbl	21,000
Weighted Average Price	$ 60.72	[2]
2020 [Member] | Carbon California [Member] | Natural Gas Swaps [Member]
Derivative agreements details:
Quantity | USD-MMBtu
Weighted Average Price		[1]
2020 [Member] | Carbon California [Member] | Natural Gas Collars [Member]
Derivative agreements details:
Quantity | USD-MMBtu
Weighted Average Price		[1]
2020 [Member] | Carbon California [Member] | Oil Swaps [Member] | WTI Bbl [Member]
Derivative agreements details:
Quantity | USD_Bbl	73,147
Weighted Average Price	$ 50.12	[2]
2020 [Member] | Carbon California [Member] | Oil Swaps [Member] | Brent Bbl [Member]
Derivative agreements details:
Quantity | USD_Bbl	139,682
Weighted Average Price	$ 65.71	[3]
2021 [Member] | Carbon California [Member] | Natural Gas Swaps [Member]
Derivative agreements details:
Quantity | USD-MMBtu
Weighted Average Price		[1]
2021 [Member] | Carbon California [Member] | Natural Gas Collars [Member]
Derivative agreements details:
Quantity | USD-MMBtu
Weighted Average Price		[1]
2021 [Member] | Carbon California [Member] | Oil Swaps [Member] | WTI Bbl [Member]
Derivative agreements details:
Quantity | USD_Bbl
Weighted Average Price		[2]
2021 [Member] | Carbon California [Member] | Oil Swaps [Member] | Brent Bbl [Member]
Derivative agreements details:
Quantity | USD_Bbl	86,341
Weighted Average Price	$ 67.12	[3]

[1] NYMEX Henry Hub Natural Gas futures contract for the respective period.

[2] NYMEX Light Sweet Crude West Texas Intermediate futures contract for the respective period.

[3] Brent future and NYMEX contracts for the respective period.