FAIR VALUE - Summary of Valuation Techniques and Quantitative Information (Detail) (USD $) In Thousands, unless otherwise specified																																													9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Level III [Member]	Dec. 31, 2012 Level III [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3, Including Swaps [Member]	Sep. 30, 2013 Other [Member]	Sep. 30, 2013 Market Approach Comparable Companies Valuation Technique [Member] Credit Oriented Investments [Member]		Sep. 30, 2013 Market Approach Comparable Companies Valuation Technique [Member] Equity [Member]		Sep. 30, 2013 Market Approach Comparable Companies Valuation Technique [Member] Real Estate Investment [Member]		Sep. 30, 2013 Market Approach Value Of Underlying Assets Valuation Technique [Member] Credit Oriented Investments [Member]		Sep. 30, 2013 Market Approach Value Of Underlying Assets Valuation Technique [Member] Equity [Member]		Sep. 30, 2013 Market Approach Value Of Underlying Assets Valuation Technique [Member] Real Estate Investment [Member]		Sep. 30, 2013 Recent Transaction Price Valuation Technique [Member] Credit Oriented Investments [Member]		Sep. 30, 2013 Recent Transaction Price Valuation Technique [Member] Equity [Member]		Sep. 30, 2013 Recent Transaction Price Valuation Technique [Member] Real Estate Investment [Member]		Sep. 30, 2013 Recent Transaction Price Valuation Technique [Member] Real estate loan portfolio [Member]		Sep. 30, 2013 Discounted Cash Flow and Sales Approach [Member] Credit Oriented Investments [Member]		Sep. 30, 2013 Discounted Cash Flow and Sales Approach [Member] Equity [Member]		Sep. 30, 2013 Recent Market Information [Member] Credit Oriented Investments [Member]		Sep. 30, 2013 Recent Market Information [Member] Equity [Member]		Sep. 30, 2013 Recent Market Information [Member] Real Estate Investment [Member]		Sep. 30, 2013 Sales Approach [Member] Real Estate Investment [Member]		Sep. 30, 2013 Discounted Cash Flow Valuation Technique [Member] Credit Oriented Investments [Member]		Sep. 30, 2013 Discounted Cash Flow Valuation Technique [Member] Real Estate Investment [Member]		Sep. 30, 2013 Discounted Cash Flow Valuation Technique [Member] Real estate loan portfolio [Member]		Sep. 30, 2013 Minimum [Member] Market Approach Comparable Companies Valuation Technique [Member] Credit Oriented Investments [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Market Approach Comparable Companies Valuation Technique [Member] Equity [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Market Approach Comparable Companies Valuation Technique [Member] Real Estate Investment [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Market Approach Value Of Underlying Assets Valuation Technique [Member] Credit Oriented Investments [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Market Approach Value Of Underlying Assets Valuation Technique [Member] Equity [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Market Approach Value Of Underlying Assets Valuation Technique [Member] Real Estate Investment [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Discounted Cash Flow and Sales Approach [Member] Credit Oriented Investments [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Recent Market Information [Member] Real Estate Investment [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Discounted Cash Flow Valuation Technique [Member] Credit Oriented Investments [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Discounted Cash Flow Valuation Technique [Member] Equity [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Discounted Cash Flow Valuation Technique [Member] Real Estate Investment [Member] Level III [Member]		Sep. 30, 2013 Minimum [Member] Discounted Cash Flow Valuation Technique [Member] Real estate loan portfolio [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Market Approach Comparable Companies Valuation Technique [Member] Credit Oriented Investments [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Market Approach Comparable Companies Valuation Technique [Member] Equity [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Market Approach Comparable Companies Valuation Technique [Member] Real Estate Investment [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Market Approach Value Of Underlying Assets Valuation Technique [Member] Credit Oriented Investments [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Market Approach Value Of Underlying Assets Valuation Technique [Member] Equity [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Market Approach Value Of Underlying Assets Valuation Technique [Member] Real Estate Investment [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Discounted Cash Flow and Sales Approach [Member] Credit Oriented Investments [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Recent Market Information [Member] Real Estate Investment [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Discounted Cash Flow Valuation Technique [Member] Credit Oriented Investments [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Discounted Cash Flow Valuation Technique [Member] Equity [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Discounted Cash Flow Valuation Technique [Member] Real Estate Investment [Member] Level III [Member]		Sep. 30, 2013 Maximum [Member] Discounted Cash Flow Valuation Technique [Member] Real estate loan portfolio [Member] Level III [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investment, at fair value	$ 38,764,427	$ 38,372,626	$ 20,131,254	$ 19,863,185	$ 20,206,051	$ 14,115	$ 1,264,193	[1]	$ 5,126,645	[1]	$ 1,013,953	[1]	$ 204,597	[1],[2]	$ 891,062	[1],[2]	$ 397,321	[1],[2]	$ 961,333	[3]	$ 1,164,874	[3]	$ 962,463	[3]	$ 496,282	[3]	$ 364,961	[4],[5]	$ 111,323	[5]	$ 984,882	[6]	$ 37,852	[6]	$ 1,162,903	[6]	$ 472,869	[4]	$ 1,245,372	[5]	$ 1,846,201	[5],[7]	$ 1,482,850	[5]
Fair Value Inputs, Discount Rate (as a percent)																																																									13.00%	[10],[4],[5],[8],[9]			8.00%	[10],[5],[8],[9]	11.00%	[10],[5],[8],[9]	8.00%	[10],[5],[7],[8],[9]	12.00%	[10],[5],[7],[8],[9]													33.00%	[10],[4],[5],[8],[9]			19.00%	[10],[5],[8],[9]	13.00%	[10],[5],[8],[9]	40.00%	[10],[5],[7],[8],[9]	30.00%	[10],[5],[7],[8],[9]
Fair Value Inputs Terminal Capitalization Rate (as a percent)																																																																	0.06	[10],[5],[7],[8],[9]																							0.15	[10],[5],[7],[8],[9]
Fair Value Inputs Direct Capitalization Rate (as a percent)																																																																	0.07	[10],[5],[7],[8],[9]																							0.09	[10],[5],[7],[8],[9]
Fair Value Inputs, Net Operating Income Growth Rate (as a percent)																																																																	1.00%	[10],[5],[7],[8],[9]																							31.00%	[10],[5],[7],[8],[9]
Fair Value Inputs Absorption Rate (as a percent)																																																																	16.00%	[10],[5],[7],[8],[9]																							33.00%	[10],[5],[7],[8],[9]
Fair Value Inputs Earnings Multiple																																													4	[1],[10],[11],[8],[9]	3	[1],[10],[11],[8],[9]	6	[1],[10],[11],[8],[9]																			9	[1],[10],[11],[8],[9]	13	[1],[10],[11],[8],[9]	12	[1],[10],[11],[8],[9]
Fair Value Inputs Underlying Asset Multiple																																																			0.9	[1],[10],[2],[8],[9]	1	[1],[10],[2],[8],[9]	1.1	[1],[10],[2],[8],[9]																			1.1	[1],[10],[2],[8],[9]	1.4	[1],[10],[2],[8],[9]	1.3	[1],[10],[2],[8],[9]
Fair Value Inputs, Quoted Prices Discount																																																											0.00%	[10],[6],[8],[9]																							6.00%	[10],[6],[8],[9]

[1] 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.

[2] 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. The Company may value the underlying assets by using prices and other relevant information from market transactions involving comparable assets.

[3] 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 changes in significant unobservable inputs, valuations of comparable companies and other similar transactions. The fair value may also be based on a pending transaction expected to close after the valuation date.

[4] 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 assets or properties, adjustments to external or internal appraised values, and the Company's assumptions regarding market trends or other relevant factors.

[5] 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, as well as certain equity investments, certain real estate-oriented investments and certain real estate loan portfolios.

[6] Certain investments are valued using quoted prices for the subject or similar securities. Generally, investments valued in this manner are classified as Level III because the quoted prices may be indicative in nature for securities that are in an inactive market, may be for similar securities, or may require adjustment for investment-specific factors or restrictions. Quoted prices include exchange-listed prices and prices obtained from brokers or pricing vendors. Prices obtained from brokers or pricing vendors are evaluated based on trading activity of the subject or similar securities or comparable-yield analysis.

[7] The discounted cash flow model for certain real estate-oriented investments and certain real estate loan portfolios 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 from market transactions involving comparable properties.

[8] The significant unobservable inputs used in the fair-value measurement of real estate investments utilizing a discounted cash flow analysis can include one or more of the following: discount rate, terminal capitalization rate, direct capitalization rate, net operating income growth rate or absorption rate. An increase (decrease) in a discount rate, terminal capitalization rate or direct capitalization rate would result in a lower (higher) fair-value measurement. An increase (decrease) in a net operating income growth rate or absorption rate would result in a 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.

[9] The discount rate is 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, as well as certain equity investments and certain real estate loan portfolios. An increase (decrease) in the discount rate would result in a lower (higher) fair-value measurement.

[10] Multiple of either earnings or underlying assets is 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. An increase (decrease) in the multiple would result in a higher (lower) fair-value measurement.

[11] Earnings multiples are based on comparable public companies and transactions with comparable companies. The Company typically utilizes multiples of EBITDA; however, in certain cases the Company may use other earnings multiples believed to be most relevant to the investment. The Company typically applies the multiple to trailing-twelve months' EBITDA. However, in certain cases other earnings measures, such as pro forma EBITDA, may be utilized if deemed to be more relevant.