Annual report pursuant to Section 13 and 15(d)

Selected Quarterly Financial Information (Summary of Quarterly Financial Information) (Details)

v3.20.1
Selected Quarterly Financial Information (Summary of Quarterly Financial Information) (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]                      
Revenues-crude oil and natural gas sales $ 21,923 $ 17,603 $ 25,230 $ 19,765 $ 27,606 $ 25,266 $ 24,426 $ 27,645 $ 84,521 $ 104,943 $ 77,025
Total operating costs and expenses 14,127 16,137 14,461 14,182 12,433 7,940 19,017 14,631 58,907 54,021 56,990
Operating income (loss) 7,776 1,501 6,370 5,546 15,206 17,320 5,723 13,038 21,193 51,287 19,951
Income (loss) from continuing operations 1,051 (3,858) (871) 830 10,504 78,626 887 8,711 (2,848) 98,728 10,272
Income (loss) from discontinued operations, net of tax (37) (61) (162) 5,671 (80) (21) (343) (52) 5,411 (496) (621)
Net income (loss) $ 1,014 $ (3,919) $ (1,033) $ 6,501 $ 10,424 $ 78,605 $ 544 $ 8,659 $ 2,563 $ 98,232 $ 9,651
Basic net income (loss) per share $ 0.02 $ (0.07) $ (0.01) $ 0.10 $ 0.17 $ 1.31 $ 0.02 $ 0.15 $ 0.04 $ 1.64 $ 0.16
Diluted net income (loss) per share 0.02 (0.07) (0.01) 0.10 0.17 1.28 0.02 0.15 0.04 1.62 0.16
Basic income (loss) from continuing operations per share 0.02 (0.07) (0.01) 0.01 0.17 1.31 0.02 0.15 (0.05) 1.65 0.17
Diluted income (loss) from continuing operations per share $ 0.02 $ (0.07) $ (0.01) $ 0.01 $ 0.17 $ 1.28 $ 0.02 $ 0.15 $ (0.05) $ 1.63 $ 0.17
Change in valuation allowance $ (1,700) $ 4,800     $ 9,000            
Recognition of deferred tax assets           $ (66,600)