Annual report pursuant to Section 13 and 15(d)

Summarized Quarterly Financial Information (unaudited) (Schedule of Quarterly Financial Information) (Details)

v3.6.0.2
Summarized Quarterly Financial Information (unaudited) (Schedule of Quarterly Financial Information) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Summarized Quarterly Financial Information (unaudited)[Abstract]                      
Total revenues $ 69,081 $ 55,927 $ 45,145 $ 30,698 $ 33,563 $ 34,316 $ 39,242 $ 30,391 $ 200,851 $ 137,512 $ 151,862
Income (loss) from operations 21,168 [1] 16,651 [1] (50,529) [1] (34,767) [1] (118,542) [2] (83,910) [2] 6,231 [2] (12,889) [2] (47,477) (209,110) 38,270
Net income (loss) (1,746) [1] 21,139 [1] (70,097) [1] (41,109) [1] (113,170) [2] (111,805) [2] (4,967) [2] (10,197) [2] (91,813) (240,139) 37,766
Income (loss) available to common shares $ (3,570) $ 19,315 $ (71,920) $ (42,933) $ (115,144) $ (113,779) $ (6,940) $ (12,171) $ (99,108) $ (248,034) $ 29,871
Basic income (loss) per share $ (0.02) $ 0.14 $ (0.61) $ (0.51) $ (1.58) $ (1.72) $ (0.11) $ (0.21) $ (0.78) $ (3.77) $ 0.67
Diluted income (loss) per share $ (0.02) $ 0.14 $ (0.61) $ (0.51) $ (1.58) $ (1.72) $ (0.11) $ (0.21) $ (0.78) $ (3.77) $ 0.65
Write-down of oil and natural gas properties     $ 61,012 $ 34,776 $ 121,134 $ 87,301     $ 95,788 $ 208,435  
[1] Loss from operations and net loss for the three months ended March, 31, 2016 and June 30, 2016 included write-downs of oil and natural gas properties of $34,776 and $61,012, respectively.
[2] Loss from operations and net loss for the three months ended September 30, 2015 and December 31, 2015 included write-downs of oil and natural gas properties of $87,301 and $121,134, respectively.