QUARTERLY SUPPLEMENTARY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Total revenues	$ 310,898	$ 282,121	$ 297,803	$ 177,805	$ 293,374	$ 298,055	$ 304,197	$ 305,539	$ 1,068,627	$ 1,201,165	$ 1,070,166
Income (loss) before income taxes	(13,524)	(55,228)	4,236	(104,999)	(28,699)	(4,528)	(4,571)	54,677	(169,515)	16,879	(9,150)
Net income (loss)	$ (8,891)	$ (37,241)	$ 5,960	$ (72,534)	$ (23,163)	$ (2,342)	$ (4,196)	$ 44,521	$ (112,706)	$ 14,820	$ 2,255
Basic earnings (loss) per share (in dollars per share)	$ (0.36)	$ (1.49)	$ 0.24	$ (2.90)	$ (0.93)	$ (0.09)	$ (0.17)	$ 1.77	$ (4.50)	$ 0.59	$ 0.09
Diluted earnings (loss) per share (in dollars per share)	$ (0.36)	$ (1.49)	$ 0.24	$ (2.90)	$ (0.93)	$ (0.09)	$ (0.17)	$ 1.74	$ (4.50)	$ 0.58	$ 0.09