Annual report pursuant to Section 13 and 15(d)

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details)

v3.10.0.1
QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]                      
Revenues $ 52,016 $ 54,610 $ 57,728 $ 57,322 $ 57,531 $ 61,385 $ 57,878 $ 54,527 $ 221,676 $ 231,321 $ 247,228
Operating income (loss) (5,629) 41,571 (9,523) 1,651 (8,359) (122,773) (276) (5,056) 28,070 (136,464) (3,369)
Net income (loss) (5,948) 31,279 (10,516) (1,357) 61,459 (81,215) (3,072) (5,787) $ 13,458 $ (28,615) $ (14,910)
Net income (loss) attributable to common shares $ (5,794) $ 31,289 $ (10,379) $ (1,194) $ 61,694 $ (81,448) $ (2,787) $ (5,620)      
Earnings (loss) per common share - basic (in dollars per share) $ (0.27) $ 1.44 $ (0.49) $ (0.06) $ 2.89 $ (3.91) $ (0.13) $ (0.27) $ 0.64 $ (1.36) $ (0.39)
Earnings (loss) per common share - diluted (in dollars per share) $ (0.27) $ 1.44 $ (0.49) $ (0.06) $ 2.89 $ (3.91) $ (0.13) $ (0.27) $ 0.64 $ (1.36) $ (0.39)