Acquisitions and Divestitures - Acquisition (Fleetwood Joint Venture) (Details) a in Thousands, $ in Thousands	1 Months Ended
	Feb. 29, 2016 USD ($)	Jun. 30, 2014 USD ($) a mi²	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Cash funding for future drilling, completion and lease acquisition costs, outstanding			$ 5,000	$ 4,409
Fleetwood Joint Venture | Louisiana
Business Acquisition [Line Items]
Purchase price		$ 24,000
Average working interest in leasehold position		37.00%
Acres acquired in leasehold position | a		30
Square miles of proprietary 3D survey | mi²		200
Cash portion of acquisition		$ 10,000
Cash funding for future drilling		$ 14,000
Cash funding for future drilling, completion and lease acquisition costs, outstanding				$ 4,400
Payments for acquisition costs	$ 4,400