Annual report pursuant to Section 13 and 15(d)

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) - Footnotes (Details)

v3.8.0.1
QUARTERLY FINANCIAL INFORMATION (UNAUDITED) - Footnotes (Details) - USD ($)
$ / shares in Units, $ 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
Error Corrections and Prior Period Adjustments Restatement [Line Items]                      
Operating income (loss) $ (8,359) $ (122,773) $ (276) $ (5,056) $ (1,421) $ 2,366 $ (3,509) $ (805) $ (136,464) $ (3,369) $ 24,294
Operating expense                 (167,446) (169,863) (171,481)
Income tax benefit                 (122,665) (3,357) 14,117
Depreciation and amortization                 (45,736) (49,315) (47,337)
Net income (loss) 61,459 (81,215) (3,072) (5,787) (5,648) (802) (4,510) (3,950) (28,615) (14,910) 7,899
Net income (loss) attributable to common shares 61,694 (81,448) $ (2,787) $ (5,620) (5,538) $ (560) $ 1,938 $ (3,818)     8,705
Gains on asset dispositions                 $ 4,507 $ 4,787 $ 5,953
Correction of Error Related to Adjustments That Were Immaterial                      
Error Corrections and Prior Period Adjustments Restatement [Line Items]                      
Operating income (loss) 300 1,200     1,700            
Operating expense (400) (200)     2,000            
Income tax benefit   900                  
Depreciation and amortization 200       500            
Net income (loss) (1,400) $ (300)     $ (1,000)            
Net income (loss) attributable to common shares $ 1,000                    
Earnings per common share $ 0.05 $ 0.02     $ 0.05            
Gains on asset dispositions         $ 300