SEGMENT REPORTING (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Reconciliation of operating profit loss from segment to consolidated
Total revenues	$ 140,450,000	$ 137,934,000
Total investment costs and expenses	81,049,000	107,792,000
Total other income (loss)	74,220,000	78,838,000
Total other expenses	34,827,000	25,000,000
Income tax expense (benefit)	458,000	(4,068,000)
Net income (loss)	98,336,000	88,048,000
Incentive fees	17,200,000
Net loss on restructuring and extinguishment of debt	20,269,000	445,000
Manager | Incentive Fees
Reconciliation of operating profit loss from segment to consolidated
Incentive fees	17,200,000	9,700,000
Credit
Reconciliation of operating profit loss from segment to consolidated
Total revenues	115,149,000	126,881,000
Total investment costs and expenses	61,399,000	99,396,000
Total other income (loss)	93,926,000	74,642,000
Total other expenses	13,968,000	12,533,000
Income tax expense (benefit)	457,000	(4,068,000)
Net income (loss)	133,251,000	93,662,000
Natural Resources
Reconciliation of operating profit loss from segment to consolidated
Total revenues	23,805,000	11,053,000
Total investment costs and expenses	19,469,000	8,396,000
Total other income (loss)	(4,746,000)	4,641,000
Total other expenses	1,630,000	1,260,000
Net income (loss)	(2,040,000)	6,038,000
Other
Reconciliation of operating profit loss from segment to consolidated
Total revenues	1,496,000
Total investment costs and expenses	181,000
Total other income (loss)	5,309,000
Total other expenses	124,000
Income tax expense (benefit)	1,000
Net income (loss)	6,499,000
Reconciling Items
Reconciliation of operating profit loss from segment to consolidated
Total other income (loss)	(20,269,000)	(445,000)
Total other expenses	19,105,000	11,207,000
Net income (loss)	(39,374,000)	(11,652,000)
Net loss on restructuring and extinguishment of debt	$ 20,269,000	$ 445,000