Six Months
Ended
December 31 Years Ended June 30
Years Ended December 31
Revenues
 Natural gas and oil sales $ 5,647  $ 5,049  $ 7,858  $ 5,624   $ 5,619  $ 3,273  $ 1,936  $ 1,297  $ 568  $ 820  $ 470  $ 280  $ 257  $ 96  $ 193  $ 111  $ 57  $ 22  $ 12 
 Marketing, gathering, compression and service operations sales   3,719   2,653   3,771   2,176   1,707   1,392   773   420   171   149   158   75   121   58   76   35   9   7   5 
  Total revenues  9,366   7,702   11,629   7,800   7,326   4,665   2,709   1,717   739   969   628   355   378   154   269   146   66   29   17 
Operating costs                   
 Production expenses   893   876   889   640   490   317   205   138   98   75   50   46   51   8   11   6   3   2   3 
 Production taxes   157   107   284   216   176   208   104   78   30   33   25   13   8   2   4   2   1   2   — 
 General and administrative expenses   453   349   377   243   139   64   37   24   18   15   13   13   20   6   9   5   4   3   3 
 Marketing, gathering, compression and service operations expenses   3,560   2,498   3,648   2,063   1,590   1,358   755   410   166   144   152   72   119   58   75   33   8   5   4 
 Depreciation, depletion and amortization   1,614   1,615   2,144   1,988   1,462   945   611   386   235   182   109   103   155   63   107   54   27   10   5 
 Impairments and other   (116 )   11,202   2,830   —   55   —   5   6   —   —   —   —   881   110   236   —   —   —   1 
  Total operating costs   6,561   16,647   10,172   5,150   3,912   2,892   1,717   1,042   547   449   349   247   1,234   247   442   100   43   22   16 
Income (loss) from operations   2,805   (8,945 )   1,457   2,650   3,414   1,773   992   675   192   520   279   108   (856 )   (93 )   (173 )   46   23   7   1 
Interest expense   (19 )   (113 )   (271 )   (401 )   (316 )   (221 )   (167 )   (154 )   (112 )   (98 )   (86 )   (81 )   (68 )   (18 )   (18 )   (14 )   (7 )   (3 )   (2 )
Other income (expense)   243   (28 )   (11 )   15   26   10   5   1   7   3   3   8   4   79   11   4   2   1   1 
Miscellaneous gains (losses)   (145 )   (202 )   (184 )   83   117   (70 )   (25 )   (21 )   (20 )   (63 )   —   —   (14 )   —   (7 )   —   —   —   — 
  Total other income (expense)   79   (343 )   (466 )   (303 )   (173 )   (281 )   (187 )   (174 )   (125 )   (158 )   (83 )   (73 )   (78 )   61   (14 )   (10 )   (5 )   (2 )   (1 )
Income (loss) before income taxes and cumulative effect of accounting change   2,884    (9,288  )   991    2,347    3,241    1,492    805   501   67   362   196   35   (934  )   (32  )   (187  )   36   18   5   — 
Income tax expense (benefit):                      
 Current   —   4   423   29   5   —   —   5   (2 )   4   —   —   —   —   —   —   —   —   — 
 Deferred   1,110   (3,487 )   (36 )   863   1,242   545   290   185   29   141   (260 )   2   —   —   (4 )   13   6   1   — 
Net income (loss) before cumulative effect of accounting change, net of tax   1,774    (5,805  )   604   1,455    1,994    947   515   311   40   217   456   33   (934  )   (32 )   (183  )   23   12   4   — 
Net (income) loss attributable to noncontrolling interest   —   (25 )   —   —   —   —   —   —   —   —   —   —   —   —   —   —   —   —   — 
Cumulative effect of accounting change, net of tax  —   —   —   —   —   —   —   2   —   —   —   —   —   —   —   —   —   —   — 
Net income (loss)  1,774   (5,830 )  604   1,455   1,994   947   515   313   40   217   456   33   (934 )  (32 )  (183 )  23   12   4   — 
Preferred stock dividends  (111 )   (23 )   (33 )   (94 )   (89 )   (42 )   (40 )   (22 )   (10 )   (2 )   (9 )   (16 )   (12 )   —   —   —   —    —  (1 )
Gain (loss) on conversion/exchange of preferred stock   —   —   (67 )   (128 )   (10 )   (26 )   (36 )   —   —   —   7   —   —   —   —   —   —   —   — 
Net income (loss) available to common shareholders $ 1,663  $ (5,853 ) $ 504  $ 1,233  $ 1,895  $ 879  $ 439  $ 291  $ 30  $ 215  $ 454  $ 17  $ (946 ) $ (32 ) $ (183 ) $ 23  $ 12  $ 4  $ (1 )