FAIR VALUE - Summary of Valuation Techniques and Quantitative Information (Detail) - Consolidated Funds $ in Thousands	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Real estate investments, at fair value	$ 230,741	$ 0
Investments, at fair value	7,358,409	6,531,385
Level III
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments, at fair value	542,743	325,922
Level III | Recent market information
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, at fair value	753
Level III | Recent transaction price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Real estate investments, at fair value	230,741
Level III | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, at fair value	130,341	2,390
Level III | Market approach (comparable companies)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, at fair value		2,099
Level III | Consumer discretionary | Recent market information
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value	16,836
Level III | Communication services | Recent market information
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value		20,746
Level III | Communication services | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value		2,416
Level III | Financials | Recent market information
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value	17,274	108,277
Level III | Financials | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value		3,608
Level III | Health care | Recent market information
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value	26,863	37,724
Level III | Health care | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value		2,550
Level III | Real estate | Recent market information
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value	16,755	79,562
Level III | Real estate | Recent transaction price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value	71,906
Level III | Real estate | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value		$ 4,570
Credit-oriented investments, measurement inputs		0.14
Level III | Other | Recent market information
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value	$ 31,274	$ 38,959
Level III | Other | Recent transaction price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value		5,078
Level III | Other | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, at fair value		$ 17,943
Discount rate | Level III | Discounted cash flow | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, measurement inputs	0.06	0.10
Discount rate | Level III | Discounted cash flow | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, measurement inputs	0.08	0.30
Discount rate | Level III | Discounted cash flow | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, measurement inputs	0.07	0.12
Discount rate | Level III | Communication services | Discounted cash flow | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.12
Discount rate | Level III | Communication services | Discounted cash flow | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.14
Discount rate | Level III | Communication services | Discounted cash flow | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.13
Discount rate | Level III | Financials | Discounted cash flow | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.09
Discount rate | Level III | Financials | Discounted cash flow | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.15
Discount rate | Level III | Financials | Discounted cash flow | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.14
Discount rate | Level III | Health care | Discounted cash flow | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.10
Discount rate | Level III | Health care | Discounted cash flow | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.16
Discount rate | Level III | Health care | Discounted cash flow | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.14
Discount rate | Level III | Real estate | Discounted cash flow | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.12
Discount rate | Level III | Real estate | Discounted cash flow | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.23
Discount rate | Level III | Other | Discounted cash flow | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.08
Discount rate | Level III | Other | Discounted cash flow | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.15
Discount rate | Level III | Other | Discounted cash flow | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Credit-oriented investments, measurement inputs		0.13
Earnings multiple | Level III | Discounted cash flow | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, measurement inputs		7
Earnings multiple | Level III | Market approach (comparable companies) | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, measurement inputs		4
Earnings multiple | Level III | Market approach (comparable companies) | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity investments, measurement inputs		10