VAALCO Energy, Inc. Annual report pursuant to Section 13 and 15(d)

Supplemental Information on Oil and Gas Producing Activities - Capitalized Costs Relating to Oil and Gas Producing Activities (Parenthetical)(Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Extractive Industries [Abstract]
Asset retirement cost	$ 5.2	$ 5.2	$ 4.7