QUARTERLY SUPPLEMENTARY 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
Continuing Operations [Abstract]
Total revenues	$ 252,062	$ 291,910	$ 275,399	$ 250,795	$ 273,355	$ 269,617	$ 258,487	$ 251,278	$ 1,070,166	$ 1,052,737	$ 996,362
Income (loss) before income taxes	(41,512)	12,598	(1,809)	21,573	29,369	(32,394)	(4,331)	23,006	(9,150)	15,650	57,497
Net income (loss)	$ (29,336)	$ 11,070	$ 157	$ 20,364	$ 45,259	$ (19,082)	$ 109	$ 18,584	$ 2,255	$ 44,870	$ 49,118
Basic earnings per share (in dollars per share)	$ (1.17)	$ 0.44	$ 0.01	$ 0.82	$ 1.81	$ (0.77)	$ 0	$ 0.73	$ 0.09	$ 1.79	$ 1.94
Diluted earnings per share (in dollars per share)	$ (1.17)	$ 0.43	$ 0.01	$ 0.80	$ 1.78	$ (0.77)	$ 0	$ 0.72	$ 0.09	$ 1.75	$ 1.90
Discontinued Operations [Abstract]
Total revenues	$ 0	$ 0	$ 0	$ 24,755	$ 28,386	$ 27,054	$ 28,492	$ 31,781	$ 24,755	$ 115,713
Income (loss) before income taxes	0	0	0	(1,349)	2,294	1,880	4,386	2,083	(1,349)	10,643
Net income (loss)	$ 0	$ 0	$ 0	$ (1,912)	$ 734	$ 1,218	$ 2,849	$ 1,352	$ (1,912)	$ 6,153	$ 786
Basic earnings per share (in dollars per share)	$ 0	$ 0	$ 0	$ (0.08)	$ 0.03	$ 0.05	$ 0.11	$ 0.05	$ (0.08)	$ 0.24	$ 0.03
Diluted earnings per share (in dollars per share)	$ 0	$ 0	$ 0	$ (0.07)	$ 0.03	$ 0.05	$ 0.11	$ 0.05	$ (0.07)	$ 0.24	$ 0.03