Annual report pursuant to Section 13 and 15(d)

Schedule I - Parent Company Financial Statement (Statements Of Condensed Unconsolidated Cash Flows) (Detail)

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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