FAIR VALUE - Summary of Valuation Techniques and Quantitative Information (Detail) (USD $) In Thousands, unless otherwise specified																																											3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Fair Value, Inputs, Level 3, Including Swaps [Member]	Mar. 31, 2013 Level III [Member]	Dec. 31, 2012 Level III [Member]	Mar. 31, 2013 Other [Member]	Mar. 31, 2013 Market Approach Comparable Companies Valuation Technique [Member] Credit Oriented Investments [Member]		Mar. 31, 2013 Market Approach Comparable Companies Valuation Technique [Member] Equity [Member]		Mar. 31, 2013 Market Approach Comparable Companies Valuation Technique [Member] Real Estate Investment [Member]		Mar. 31, 2013 Market Approach Value Of Underlying Assets Valuation Technique [Member] Credit Oriented Investments [Member]		Mar. 31, 2013 Market Approach Value Of Underlying Assets Valuation Technique [Member] Equity [Member]		Mar. 31, 2013 Market Approach Value Of Underlying Assets Valuation Technique [Member] Real Estate Investment [Member]		Mar. 31, 2013 Recent Transaction Price Valuation Technique [Member] Credit Oriented Investments [Member]		Mar. 31, 2013 Recent Transaction Price Valuation Technique [Member] Real Estate Loan Portfolio [Member]		Mar. 31, 2013 Recent Transaction Price Valuation Technique [Member] Equity [Member]		Mar. 31, 2013 Recent Transaction Price Valuation Technique [Member] Real Estate Investment [Member]		Mar. 31, 2013 Recent Market Information [Member] Credit Oriented Investments [Member]		Mar. 31, 2013 Recent Market Information [Member] Real Estate Loan Portfolio [Member]		Mar. 31, 2013 Recent Market Information [Member] Equity [Member]		Mar. 31, 2013 Recent Market Information [Member] Real Estate Investment [Member]		Mar. 31, 2013 Sales Approach [Member] Real Estate Investment [Member]		Mar. 31, 2013 Discounted Cash Flow Valuation Technique [Member] Credit Oriented Investments [Member]		Mar. 31, 2013 Discounted Cash Flow Valuation Technique [Member] Real Estate Loan Portfolio [Member]		Mar. 31, 2013 Discounted Cash Flow Valuation Technique [Member] Real Estate Investment [Member]		Mar. 31, 2013 Minimum [Member] Credit Oriented Investments [Member]		Mar. 31, 2013 Minimum [Member] Real Estate Loan Portfolio [Member]		Mar. 31, 2013 Minimum [Member] Equity [Member]		Mar. 31, 2013 Minimum [Member] Real Estate Investment [Member]		Mar. 31, 2013 Maximum [Member] Credit Oriented Investments [Member]		Mar. 31, 2013 Maximum [Member] Real Estate Loan Portfolio [Member]		Mar. 31, 2013 Maximum [Member] Equity [Member]		Mar. 31, 2013 Maximum [Member] Real Estate Investment [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Discount Rate																																											7.00%	[1],[2],[3]	13.00%	[1],[2],[3]			8.00%	[1],[2],[3]	16.00%	[1],[2],[3]	20.00%	[1],[2],[3]			40.00%	[1],[2],[3]
Investment, at fair value	$ 37,792,913	$ 38,372,626	$ 19,175,428	$ 19,120,754	$ 19,863,185	$ 15,490	$ 1,182,300	[4]	$ 5,974,128	[4]	$ 947,724	[4]	$ 201,469	[4],[5]	$ 384,353	[4],[5]	$ 946,529	[4],[5]	$ 1,465,340	[6]	$ 699,061	[6]	$ 974,537	[6]	$ 662,009	[6]	$ 962,983	[7]	$ 390,426	[8]	$ 562,660	[7]	$ 156,087	[7]	$ 289,187	[9]	$ 1,222,858	[10]	$ 640,897	[10]	$ 1,497,390	[10],[11]
Fair Value Inputs Terminal Capitalization Rate																																																	0.06	[1],[2],[3]							0.11	[1],[2],[3]
Fair Value Inputs Direct Capitalization Rate																																																	0.07	[1],[2],[3]							0.08	[1],[2],[3]
Fair Value Inputs, Net Operating Income Growth Rate																																																	3.00%	[1],[2],[3]							34.00%	[1],[2],[3]
Fair Value Inputs Absorption Rate																																																	13.00%	[1],[2],[3]							33.00%	[1],[2],[3]
Fair Value Inputs Earnings Multiple																																											4	[1],[2],[3]			3	[1],[2],[3]	6	[1],[2],[3]	12	[1],[2],[3]			13	[1],[2],[3]	14	[1],[2],[3]
Fair Value Inputs Underlying Asset Multiple																																											0.9	[1],[2],[3]			1.0	[1],[2],[3]	1.7	[1],[2],[3]	1.1	[1],[2],[3]			1.2	[1],[2],[3]	1.8	[1],[2],[3]

[1] The significant unobservable input used in the market approach for the fair-value measurement of distressed credit-oriented investments, credit-oriented investments in which the consolidated funds have a controlling interest in the underlying issuer, equity investments and certain real estate-oriented investments is a multiple of earnings or a multiple of underlying assets. A significant increase (decrease) in these multiples would result in a significantly higher (lower) fair-value measurement.

[2] The significant unobservable input used in the fair-value measurement of performing credit-oriented investments in which the consolidated funds do not have a controlling interest in the underlying issuer is the discount rate. A significant increase (decrease) in the discount rate would result in a significantly lower (higher) fair-value measurement.

[3] The significant unobservable inputs used in the fair-value measurement of real estate investments valued using a discounted cash flow analysis can include a discount rate, terminal capitalization rate, direct capitalization rate, net operating income growth rate and/or absorption rate. A significant increase (decrease) in a discount rate, terminal capitalization rate or direct capitalization rate would result in a significantly lower (higher) fair-value measurement. A significant increase (decrease) in a net operating income growth rate or absorption rate would result in a significantly higher (lower) fair-value measurement. Generally, a change in a net operating income growth rate or absorption rate would be accompanied by a directionally similar change in the discount rate.

[4] A market approach is generally used to value distressed investments and investments in which the consolidated funds have a controlling interest in the underlying issuer.

[5] A market approach using the value of underlying assets utilizes a multiple, based on comparable companies, of underlying assets or the net book value of the portfolio company. The Company typically obtains the value of underlying assets from the underlying portfolio company's financial statements or from pricing vendors. In some cases, the Company may value the underlying assets by using prices and other relevant information generated by market transactions involving comparable assets.

[6] Certain investments are valued based on recent transactions, generally defined as investments purchased or sold within six months of the valuation date, adjusted when appropriate based on consideration of any changes in significant unobservable inputs, valuations of comparable companies and other similar transactions. In other cases, the fair value may be based on a pending transaction expected to occur after the valuation date.

[7] Certain investments are valued using broker quotes for the subject security and/or similar securities.

[8] Certain real estate loan portfolios are valued utilizing a combination of recent market information for similar loan pools as well as an evaluation of the underlying collateral, which is typically performed using a sales approach. In evaluating the loan pools as a whole, inputs can include recent market transactions and/or broker quotations involving similar loan pools. In evaluating the value of the underlying collateral, the sales approach uses prices and other relevant information generated by market transactions involving comparable assets. The significant unobservable inputs used in the sales approach generally include adjustments to transactions involving comparable properties, adjustments to external or internal appraised values and the Company's assumptions regarding market trends or other relevant factors.

[9] The sales approach uses prices and other relevant information generated by market transactions involving comparable assets. The significant unobservable inputs used in the sales approach generally include adjustments to transactions involving comparable properties, adjustments to external or internal appraised values and the Company's assumptions regarding market trends or other relevant factors.

[10] A discounted cash flow method is generally used to value performing credit-oriented investments in which the consolidated funds do not have a controlling interest in the underlying issuer, certain real estate-oriented investments and certain real estate loan portfolios.

[11] The discounted cash flow model for certain real estate-oriented investments contains a sell-out analysis. In these cases, the discounted cash flow is based on the expected timing and prices of sales of the underlying properties. The Company's determination of the sales prices of these properties typically includes consideration of prices and other relevant information generated by market transactions involving comparable properties.