Acquisition (Schedule of Assets Acquired and Liabilities Assumed) (Details) (Gulf of Mexico Acquisition [Member], USD $) In Thousands, unless otherwise specified	Jul. 03, 2013
Gulf of Mexico Acquisition [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Oil and gas properties	$ 192,067
Unevaluated oil and gas properties	12,033
Asset retirement obligations	(15,319)
Net assets to be acquired	$ 188,781