BORROWINGS (Details 6) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
1 - 3 years	$ 107,789
3 - 5 years	1,736,579
More than 5 years	4,547,489
Total borrowings	6,391,857
CLO 2005-1 senior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
3 - 5 years	429,903
Total borrowings	429,903
CLO 2005-2 senior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
3 - 5 years	474,538
Total borrowings	474,538
CLO 2006-1 senior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	601,091
Total borrowings	601,091
CLO 2007-1 senior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	2,075,040
Total borrowings	2,075,040
CLO 2007-1 junior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	232,491
Total borrowings	232,491
CLO 2007-A senior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
3 - 5 years	601,375
Total borrowings	601,375
CLO 2007-A junior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
3 - 5 years	10,821
Total borrowings	10,821
CLO 2012-1 senior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	367,500
Total borrowings	367,500
CLO 2012-1 junior secured notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	21,500
Total borrowings	21,500
CLO 2007-1 junior secured notes to affiliates | Affiliates
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	249,115
Total borrowings	249,115
CLO 2007-A junior secured notes to affiliates | Affiliates
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
3 - 5 years	47,442
Total borrowings	47,442
CLO 2011-1 senior debt
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	343,485
Total borrowings	343,485
2015 Natural Resources Facility
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
1 - 3 years	107,789
Total borrowings	107,789
Convertible senior notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
3 - 5 years	172,500
Total borrowings	172,500
Senior notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	373,750
Total borrowings	373,750
Junior subordinated notes
Entity's contractual obligations (excluding interest) under borrowing agreements, payments due by period
More than 5 years	283,517
Total borrowings	$ 283,517