Schedule I - Parent Company Financial Statement (Statements Of Condensed Unconsolidated Cash Flows) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 3,431	$ (322)	$ 2,283	$ 4,259	$ (3,641)	$ (14,767)	$ (518)	$ (7,624)	$ 9,651	$ (26,550)	$ (158,656)
Adjustments to reconcile net income (loss) to net cash provided by
Depreciation, depletion and amortization									6,457	6,926	32,998
Deferred tax asset									(1,260)		1,349
Stock-based compensation									1,098	192	3,810
Commodity derivatives net (gain) loss									(1,032)	(1,711)
Cash settlements received on matured derivative contracts									195
Change in operating assets and liabilities:
Other receivables									(43)	(18)	(609)
Prepayments and other									1,646	517	3,129
Accounts payable									(7,297)	(15,459)	30,187
Accrued liabilities and other									2,050	(4,586)	3,034
Net cash provided by (used in) operating activities									6,659	(3,452)	38,875
CASH FLOWS FROM INVESTING ACTIVITIES
Decrease in restricted cash									(150)	15,219	5,536
Net cash used in investing activities									(1,649)	(1,287)	(83,010)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuances of common stock									39		441
Treasury shares									(20)	(51)
Net cash provided by (used in) financing activities									(5,815)	(144)	441
NET CHANGE IN CASH AND CASH EQUIVALENTS									(805)	(4,883)	(43,694)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR				20,474				$ 25,357	20,474	25,357	69,051
CASH AND CASH EQUIVALENTS AT END OF YEAR	19,669				20,474				19,669	20,474	25,357
VAALCO ENERGY, INC. [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)									9,651	(26,550)	(158,656)
Adjustments to reconcile net income (loss) to net cash provided by
Depreciation, depletion and amortization									260	244	240
Other operating loss, net									12
Deferred tax asset									(1,260)		1,349
Stock-based compensation									1,098	192	3,810
Equity in (earnings) loss from subsidiaries									(18,196)	16,732	146,495
Commodity derivatives net (gain) loss									1,032
Cash settlements received on matured derivative contracts									195
Change in operating assets and liabilities:
Other receivables									(80)	(21)	293
Prepayments and other									(130)	(955)	(236)
Accounts payable									(212)	(658)	753
Accrued liabilities and other									(272)	(1,855)	517
Net cash provided by (used in) operating activities									(7,902)	(12,871)	(5,435)
CASH FLOWS FROM INVESTING ACTIVITIES
Investment in subsidiaries											(7,044)
Return of investment in subsidiaries									7,598	12,556
Decrease in restricted cash									(50)	1,582	8,418
Property and equipment expenditures									(127)	(178)	(160)
Net cash used in investing activities									7,421	13,960	1,214
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuances of common stock									39		441
Treasury shares									(20)	(51)
Net cash provided by (used in) financing activities									19	(51)	441
NET CHANGE IN CASH AND CASH EQUIVALENTS									(462)	1,038	(3,780)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR				$ 1,038					1,038		$ 3,780
CASH AND CASH EQUIVALENTS AT END OF YEAR	$ 576				$ 1,038				$ 576	$ 1,038