BORROWINGS (Details) (USD $)						12 Months Ended																		0 Months Ended	12 Months Ended				0 Months Ended	12 Months Ended								0 Months Ended		12 Months Ended		0 Months Ended	12 Months Ended						12 Months Ended		12 Months Ended							0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012 Affiliates	Dec. 31, 2013 Nonaffiliates	Dec. 31, 2012 Nonaffiliates	Dec. 31, 2013 CLO 2005-1 senior secured notes	Dec. 31, 2012 CLO 2005-1 senior secured notes	Dec. 31, 2013 CLO 2005-2 senior secured notes	Dec. 31, 2012 CLO 2005-2 senior secured notes	Dec. 31, 2013 CLO 2006-1 senior secured notes	Dec. 31, 2012 CLO 2006-1 senior secured notes	Dec. 31, 2013 CLO 2007-1 senior secured notes	Dec. 31, 2012 CLO 2007-1 senior secured notes	Dec. 31, 2013 CLO 2007-1 mezzanine notes Nonaffiliates	Dec. 31, 2012 CLO 2007-1 mezzanine notes Nonaffiliates	Dec. 31, 2013 CLO 2007-1 subordinated notes Nonaffiliates	Dec. 31, 2012 CLO 2007-1 subordinated notes Nonaffiliates	Dec. 31, 2013 CLO 2007-A senior secured notes	Dec. 31, 2012 CLO 2007-A senior secured notes	Dec. 31, 2013 CLO 2007-A mezzanine notes Nonaffiliates	Dec. 31, 2012 CLO 2007-A mezzanine notes Nonaffiliates	Dec. 31, 2013 CLO 2007-A subordinated notes Nonaffiliates	Dec. 31, 2012 CLO 2007-A subordinated notes Nonaffiliates	Sep. 27, 2013 CLO 2011-1 senior debt	Dec. 31, 2013 CLO 2011-1 senior debt	Dec. 31, 2012 CLO 2011-1 senior debt	Dec. 31, 2013 CLO 2012-1 senior secured notes	Dec. 31, 2012 CLO 2012-1 senior secured notes	Dec. 21, 2012 CLO 2012-1 senior secured notes Nonaffiliates	Dec. 31, 2013 CLO 2012-1 subordinated notes	Dec. 31, 2012 CLO 2012-1 subordinated notes	Dec. 31, 2012 CLO 2007-1 mezzanine notes to affiliates Affiliates	Dec. 31, 2012 CLO 2007-1 subordinated notes to affiliates Affiliates	Dec. 31, 2012 CLO 2007-A mezzanine notes to affiliates Affiliates	Dec. 31, 2012 CLO 2007-A subordinated notes to affiliates Affiliates	Dec. 31, 2013 2015 Facility	Dec. 31, 2012 2015 Facility	Nov. 30, 2012 2015 Facility LIBOR	Nov. 14, 2013 2015 Natural Resources Facility	Dec. 31, 2013 2015 Natural Resources Facility	Dec. 31, 2012 2015 Natural Resources Facility	Feb. 27, 2013 2018 Natural Resources Facility	Dec. 31, 2013 2018 Natural Resources Facility	Dec. 31, 2013 2018 Natural Resources Facility LIBOR	Dec. 31, 2013 2018 Natural Resources Facility Minimum LIBOR	Dec. 31, 2013 2018 Natural Resources Facility Maximum LIBOR	Dec. 31, 2013 Total credit facilities	Dec. 31, 2012 Total credit facilities	Dec. 31, 2012 7.5% Convertible Senior Notes	Jan. 18, 2013 7.5% Convertible Senior Notes	Dec. 31, 2013 8.375% Senior Notes	Dec. 31, 2012 8.375% Senior Notes	Dec. 31, 2013 7.500% Senior notes due March 20, 2042	Dec. 31, 2012 7.500% Senior notes due March 20, 2042	Dec. 31, 2013 Junior subordinated notes	Dec. 31, 2012 Junior subordinated notes	Dec. 31, 2013 CLO 2013-1 senior secured notes	Jun. 25, 2013 CLO 2013-1 senior secured notes Nonaffiliates
Details of Company's borrowings
Collateralized loan obligation secured debt				$ 5,249,383,000	$ 5,122,338,000	$ 193,909,000	$ 427,317,000	$ 335,570,000	$ 470,516,000	$ 384,925,000	$ 601,091,000	$ 2,075,040,000	$ 2,075,040,000	$ 406,428,000	$ 203,727,000	$ 136,097,000	$ 5,828,000	$ 428,152,000	$ 601,375,000	$ 55,327,000	$ 5,580,000	$ 15,096,000	$ 4,599,000		$ 388,703,000	$ 343,485,000	$ 362,727,000	$ 362,280,000		$ 18,000,000	$ 21,500,000																										$ 449,409,000
Collateralized loan obligation junior secured notes to affiliates			296,557,000																													118,845,000	130,270,000	36,945,000	10,497,000
Senior notes	362,276,000	362,178,000																																																	250,800,000	250,735,000	111,476,000	111,443,000
Credit facilities	125,289,000	107,789,000																																		75,000,000				50,289,000	107,789,000						125,289,000	107,789,000
Convertible senior notes		166,028,000																																															166,028,000	172,500,000
Junior subordinated notes	283,517,000	283,517,000																																																					283,517,000	283,517,000
Total borrowings	6,020,465,000	6,338,407,000																																															166,000,000
Weighted Average Borrowing Rate (as a percent)						0.73%	0.69%	0.63%	0.66%	0.69%	0.69%	0.79%	0.86%	3.65%	2.81%	18.15%	26.22%	1.57%	1.50%	7.44%	7.02%	42.22%	60.24%		1.25%	1.67%	2.34%	2.58%		11.67%		6.29%	25.89%	7.53%	60.24%	1.39%	2.56%			2.42%	2.71%				1.75%	3.25%			7.50%		8.38%	8.38%	7.50%	7.50%	5.39%	5.43%	1.98%
Weighted Average Remaining Maturity						1212 days	1577 days	1426 days	1791 days	1698 days	2063 days	2692 days	3057 days	2692 days	3057 days	2692 days	3057 days	1384 days	1749 days	1384 days	1749 days	1384 days	1749 days		1688 days	2053 days	4002 days	4367 days		4002 days	4367 days	3057 days	3057 days	1749 days	1749 days	699 days	1064 days			674 days	1039 days		1519 days						1476 days		10181 days	10546 days	10306 days	10671 days	8347 days	8712 days	4214 days
Total borrowings, fair value of collateral	6,645,905,000	6,237,994,000	331,037,000	6,431,970,000	5,679,542,000	303,104,000	510,187,000	496,917,000	618,000,000	649,894,000	846,365,000	2,354,938,000	2,298,373,000	461,250,000	225,654,000	154,456,000	6,455,000	540,677,000	698,569,000	69,867,000	6,482,000	19,063,000	5,342,000		517,597,000	421,584,000	376,603,000	40,180,000		18,689,000	2,351,000	131,636,000	144,291,000	42,916,000	12,194,000					213,935,000	227,415,000						213,935,000	227,415,000									468,915,000
Principal cash held																												$ 357,700,000
Debt, variable interest rate basis																								three-month LIBOR					three-month LIBOR									LIBOR	LIBOR	LIBOR		LIBOR		LIBOR														three-month LIBOR