QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net revenues	$ 318,480	$ 318,584	$ 320,403	$ 324,766	$ 326,124	$ 327,066	$ 325,176	$ 325,662	$ 1,282,233	$ 1,304,028	$ 1,336,542
Operating income	34,329	32,508	30,015	38,326	21,029	37,352	39,780	37,352	135,178	135,513	81,281
Net income (loss) attributable to common shareholders	$ 12,414	$ (4,721)	$ (55,356)	$ (62,099)	$ (6,920)	$ 14,510	$ 13,840	$ 15,547	$ (109,762)	$ 36,977	$ (20,383)
Basic earnings (loss) per share	$ 0.12	$ (0.05)	$ (0.71)	$ (0.80)	$ (0.09)	$ 0.20	$ 0.19	$ 0.22	$ (1.26)	$ 0.47	$ (0.29)
Diluted earnings (loss) per share	$ 0.12	$ (0.05)	$ (0.71)	$ (0.80)	$ (0.09)	$ 0.20	$ 0.19	$ 0.22	$ (1.26)	$ 0.47	$ (0.29)
Change In Fair Value of Contingent Payment Rights									$ (86,476)	$ 23,802
Gain (loss) on extinguishment of debt					$ (18,500)				(17,101)	(18,264)	$ 4,510
Severance costs incurred					7,500
Plan settlement	$ 5,900
Transaction costs										7,646
Transaction costs associated with CPRs issued										7,600
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Interest expense					7,900
Change In Fair Value of Contingent Payment Rights	$ 13,100				23,800				$ (86,500)	$ 23,500
Transaction costs associated with CPRs issued					$ 7,600