Fair Value Measurements of Financial Instruments (Details) $ in Thousands	Mar. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Fair Value Measurements of Financial Instruments
Number of bank counterparties for company's commodity derivative contracts | item	4
Recurring | Total | Commodity Derivatives
Derivative Assets:
Total assets	$ 6,255	$ 4,384,000
Derivative Liabilities:
Gross Recognized Liabilities	(13,267)	(7,617,000)
Recurring | Total | Commodity Derivatives | Swaps | Oil
Derivative Assets:
Total assets	2
Derivative Liabilities:
Gross Recognized Liabilities	(4,293)	(3,679,000)
Recurring | Total | Commodity Derivatives | Swaps | Natural gas
Derivative Assets:
Total assets	74	821,000
Derivative Liabilities:
Gross Recognized Liabilities	(205)
Recurring | Total | Commodity Derivatives | Collars | Oil
Derivative Assets:
Total assets	4,764	952,000
Derivative Liabilities:
Gross Recognized Liabilities	(8,208)	(2,605,000)
Recurring | Total | Commodity Derivatives | Collars | Natural gas
Derivative Assets:
Total assets	1,415	2,611,000
Derivative Liabilities:
Gross Recognized Liabilities	(561)	(1,333,000)
Recurring | Significant Other Observable Inputs (Level 2) | Commodity Derivatives
Derivative Assets:
Total assets	6,255	4,384,000
Derivative Liabilities:
Gross Recognized Liabilities	(13,267)	(7,617,000)
Recurring | Significant Other Observable Inputs (Level 2) | Commodity Derivatives | Swaps | Oil
Derivative Assets:
Total assets	2
Derivative Liabilities:
Gross Recognized Liabilities	(4,293)	(3,679,000)
Recurring | Significant Other Observable Inputs (Level 2) | Commodity Derivatives | Swaps | Natural gas
Derivative Assets:
Total assets	74	821,000
Derivative Liabilities:
Gross Recognized Liabilities	(205)
Recurring | Significant Other Observable Inputs (Level 2) | Commodity Derivatives | Collars | Oil
Derivative Assets:
Total assets	4,764	952,000
Derivative Liabilities:
Gross Recognized Liabilities	(8,208)	(2,605,000)
Recurring | Significant Other Observable Inputs (Level 2) | Commodity Derivatives | Collars | Natural gas
Derivative Assets:
Total assets	1,415	2,611,000
Derivative Liabilities:
Gross Recognized Liabilities	$ (561)	$ (1,333,000)