BORROWINGS (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Details of Company's borrowings
Total borrowings	$ 5,178,657	$ 5,540,207
Carrying value	4,548,688	4,843,746
Total borrowings, carrying value	5,210,208	5,505,250
Collateral amount	4,699,895	5,169,916
CLO 2007-1 secured notes
Details of Company's borrowings
Par	1,431,783	1,544,032
Carrying value	$ 1,537,984	$ 1,630,293
Weighted Average Borrowing Rate (as a percent)	2.47%	2.10%
Weighted Average Remaining Maturity (in days)	1871 days	1962 days
Collateral amount	$ 1,530,018	$ 1,732,855
CLO 2007-1 subordinated notes
Details of Company's borrowings
Par	134,468	134,468
Carrying value	$ 74,058	$ 74,954
Weighted Average Borrowing Rate (as a percent)	4.53%	11.66%
Weighted Average Remaining Maturity (in days)	1871 days	1962 days
Collateral amount	$ 143,694	$ 150,912
CLO 2007-A subordinated notes
Details of Company's borrowings
Par	15,096	15,096
Carrying value	$ 15,640	$ 17,060
Weighted Average Borrowing Rate (as a percent)	6.59%	14.49%
Weighted Average Remaining Maturity (in days)	563 days	654 days
Collateral amount	$ 43,222	$ 48,856
CLO 2011-1 senior debt
Details of Company's borrowings
Par		249,301
Carrying value		$ 249,301
Weighted Average Borrowing Rate (as a percent)		1.67%
Weighted Average Remaining Maturity (in days)		1689 days
Collateral amount		$ 310,498
CLO 2012-1 secured notes
Details of Company's borrowings
Par	367,500	367,500
Carrying value	$ 372,968	$ 365,383
Weighted Average Borrowing Rate (as a percent)	2.70%	2.59%
Weighted Average Remaining Maturity (in days)	3181 days	3272 days
Collateral amount	$ 365,848	$ 361,684
CLO 2012-1 subordinated notes
Details of Company's borrowings
Par	18,000	18,000
Carrying value	$ 8,960	$ 10,845
Weighted Average Borrowing Rate (as a percent)	14.06%	15.82%
Weighted Average Remaining Maturity (in days)	3181 days	3272 days
Collateral amount	$ 17,919	$ 17,715
CLO 2013-1 secured notes
Details of Company's borrowings
Par	458,500	458,500
Carrying value	$ 461,576	$ 450,280
Weighted Average Borrowing Rate (as a percent)	2.34%	2.05%
Weighted Average Remaining Maturity (in days)	3393 days	3484 days
Collateral amount	$ 481,092	$ 479,391
CLO 2013-2 secured notes
Details of Company's borrowings
Par	339,250	339,250
Carrying value	$ 340,151	$ 334,187
Weighted Average Borrowing Rate (as a percent)	2.80%	2.52%
Weighted Average Remaining Maturity (in days)	3585 days	3676 days
Collateral amount	$ 349,842	$ 347,989
CLO 9 secured notes
Details of Company's borrowings
Par	463,750	463,750
Carrying value	$ 460,374	$ 454,103
Weighted Average Borrowing Rate (as a percent)	2.63%	2.33%
Weighted Average Remaining Maturity (in days)	3850 days	3941 days
Collateral amount	$ 459,889	$ 463,574
CLO 9 subordinated notes
Details of Company's borrowings
Par	15,000	15,000
Carrying value	$ 8,879	$ 9,972
Weighted Average Borrowing Rate (as a percent)	14.62%	15.92%
Weighted Average Remaining Maturity (in days)	3850 days	3941 days
Collateral amount	$ 14,875	$ 14,994
CLO 10 secured notes
Details of Company's borrowings
Par	368,000	368,000
Carrying value	$ 370,038	$ 363,977
Weighted Average Borrowing Rate (as a percent)	2.87%	2.75%
Weighted Average Remaining Maturity (in days)	3546 days	3637 days
Collateral amount	$ 381,593	$ 384,991
CLO 11 secured notes
Details of Company's borrowings
Par	507,750	507,750
Carrying value	$ 500,174	$ 491,699
Weighted Average Borrowing Rate (as a percent)	2.68%	2.38%
Weighted Average Remaining Maturity (in days)	4032 days	4123 days
Collateral amount	$ 500,785	$ 501,286
CLO 11 subordinated notes
Details of Company's borrowings
Par	28,250	28,250
Carrying value	$ 20,623	$ 23,306
Weighted Average Borrowing Rate (as a percent)	16.84%	5.28%
Weighted Average Remaining Maturity (in days)	4032 days	4123 days
Collateral amount	$ 27,862	$ 27,890
CLO 13 secured notes
Details of Company's borrowings
Par	370,000	370,000
Carrying value	$ 374,429	$ 364,986
Weighted Average Borrowing Rate (as a percent)	2.84%	2.84%
Weighted Average Remaining Maturity (in days)	4308 days	4399 days
Collateral amount	$ 379,157	$ 323,781
CLO 13 secured notes
Details of Company's borrowings
Par	4,000	4,000
Carrying value	$ 2,834	$ 3,400
Weighted Average Borrowing Rate (as a percent)	0.00%	0.00%
Weighted Average Remaining Maturity (in days)	4308 days	4399 days
Collateral amount	$ 4,099	$ 3,500
Total collateralized loan obligation secured debt
Details of Company's borrowings
Par	4,521,347	4,882,897
Carrying value	4,548,688	4,843,746
Collateral amount	4,699,895	5,169,916
8.375% Senior notes
Details of Company's borrowings
Par	258,750	258,750
Carrying value	$ 289,350	$ 289,660
Weighted Average Borrowing Rate (as a percent)	8.38%	8.38%
Weighted Average Remaining Maturity (in days)	9360 days	9451 days
7.500% Senior notes
Details of Company's borrowings
Par	$ 115,043	$ 115,043
Carrying value	$ 123,267	$ 123,346
Weighted Average Borrowing Rate (as a percent)	7.50%	7.50%
Weighted Average Remaining Maturity (in days)	9485 days	9576 days
Junior subordinated notes
Details of Company's borrowings
Par	$ 283,517	$ 283,517
Carrying value	$ 248,903	$ 248,498
Weighted Average Borrowing Rate (as a percent)	5.57%	5.43%
Weighted Average Remaining Maturity (in days)	7493 days	7584 days