Acquisitions (Fleetwood Joint Venture) (Details) (Fleetwood Joint Venture, Louisiana, USD $) In Millions, unless otherwise specified	1 Months Ended
	Jun. 30, 2014 sqmi acre	Jul. 31, 2014 Subsequent Event
Business Acquisition [Line Items]
Purchase price	$ 24
Average working interest in leasehold position	37.00%
Acres acquired in leasehold position	30,000
Square miles of proprietary 3D survey	200
Cash portion of acquisition	10.0	3.0
Cash payment in January 2015	7
Cash funding for future drilling	$ 14