Fair Value Measurements of Financial Instruments (Details) (Recurring, Commodity Derivatives, USD $) In Thousands, unless otherwise specified	Jun. 30, 2014 item	Dec. 31, 2013 item
Significant Other Observable Inputs (Level 2)
Fair Value Measurements of Financial Instruments
Number of bank counterparties for company's commodity derivative contracts	7	7
Assets:
Total assets	$ 907	$ 2,578
Liabilities:
Total liabilities	53,911	33,390
Significant Other Observable Inputs (Level 2) | Swaps | NGL
Assets:
Total assets	153	469
Liabilities:
Total liabilities	66	74
Significant Other Observable Inputs (Level 2) | Swaps | Gas
Assets:
Total assets	17	488
Liabilities:
Total liabilities	3,830	809
Significant Other Observable Inputs (Level 2) | Swaps | Oil
Liabilities:
Total liabilities	49,455	32,209
Significant Other Observable Inputs (Level 2) | Collars | Gas
Assets:
Total assets	124	751
Liabilities:
Total liabilities	32	26
Significant Other Observable Inputs (Level 2) | Collars | Oil
Assets:
Total assets		64
Liabilities:
Total liabilities	528	272
Significant Other Observable Inputs (Level 2) | Basis Differential Swaps
Assets:
Total assets	613	806
Total
Assets:
Total assets	907	2,578
Liabilities:
Total liabilities	53,911	33,390
Total | Swaps | NGL
Assets:
Total assets	153	469
Liabilities:
Total liabilities	66	74
Total | Swaps | Gas
Assets:
Total assets	17	488
Liabilities:
Total liabilities	3,830	809
Total | Swaps | Oil
Liabilities:
Total liabilities	49,455	32,209
Total | Collars | Gas
Assets:
Total assets	124	751
Liabilities:
Total liabilities	32	26
Total | Collars | Oil
Assets:
Total assets		64
Liabilities:
Total liabilities	528	272
Total | Basis Differential Swaps
Assets:
Total assets	$ 613	$ 806