FAIR VALUE MEASUREMENTS - Valuation Methodologies and Significant Unobservable Inputs (Details)	9 Months Ended
	Sep. 30, 2020 USD ($) $ / barrel
Illiquidity Discount | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.05
Level III
Level III investments and other financial instruments by valuation methodologies
Private equity, fair value	$ 12,626,979,000
Credit, fair value	8,723,978,000
Real assets, fair value	4,440,105,000
Equity method - other, fair value	1,932,859,000
Other investments, fair value	$ 1,894,329,000
Level III | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.093
Other investments, measurement input	0.085
Level III | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.050
Other investments, measurement input	0.050
Level III | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.150
Other investments, measurement input	0.200
Level III | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.426
Other investments, measurement input	0.350
Level III | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.000
Other investments, measurement input	0.000
Level III | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	1.000
Other investments, measurement input	1.000
Level III | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.465
Other investments, measurement input	0.406
Level III | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.000
Other investments, measurement input	0.000
Level III | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	1.000
Other investments, measurement input	1.000
Level III | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.109
Other investments, measurement input	0.244
Level III | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.000
Other investments, measurement input	0.000
Level III | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	1.000
Other investments, measurement input	1.000
Level III | Enterprise Value/LTM EBITDA Multiple | Market comparables | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	13.7
Other investments, measurement input	14.2
Level III | Enterprise Value/LTM EBITDA Multiple | Market comparables | Minimum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	9.4
Other investments, measurement input	1.4
Level III | Enterprise Value/LTM EBITDA Multiple | Market comparables | Maximum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	28.1
Other investments, measurement input	28.5
Level III | Enterprise Value/Forward EBITDA Multiple | Market comparables | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	14.4
Other investments, measurement input	14.0
Level III | Enterprise Value/Forward EBITDA Multiple | Market comparables | Weighted Average | Infrastructure
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	10.9
Level III | Enterprise Value/Forward EBITDA Multiple | Market comparables | Minimum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	7.2
Other investments, measurement input	1.3
Level III | Enterprise Value/Forward EBITDA Multiple | Market comparables | Maximum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	22.4
Other investments, measurement input	26.5
Level III | Weighted Average Cost of Capital | Discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.084
Other investments, measurement input	0.147
Level III | Weighted Average Cost of Capital | Discounted cash flow | Weighted Average | Infrastructure
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.084
Level III | Weighted Average Cost of Capital | Discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.055
Other investments, measurement input	0.083
Level III | Weighted Average Cost of Capital | Discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	0.175
Other investments, measurement input	0.250
Level III | Enterprise Value/LTM EBITDA Exit Multiple | Discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	11.0
Other investments, measurement input	9.2
Level III | Enterprise Value/LTM EBITDA Exit Multiple | Discounted cash flow | Weighted Average | Infrastructure
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	10.0
Level III | Enterprise Value/LTM EBITDA Exit Multiple | Discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	6.0
Other investments, measurement input	6.9
Level III | Enterprise Value/LTM EBITDA Exit Multiple | Discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Equity method - other, measurement input	18.0
Other investments, measurement input	11.0
Level III | Yield | Yield Analysis | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	0.083
Level III | Yield | Yield Analysis | Minimum
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	0.052
Level III | Yield | Yield Analysis | Maximum
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	0.375
Level III | Net Leverage | Yield Analysis | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	5.1
Level III | Net Leverage | Yield Analysis | Minimum
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	0.3
Level III | Net Leverage | Yield Analysis | Maximum
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	19.3
Level III | EBITDA Multiple | Yield Analysis | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	9.6
Level III | EBITDA Multiple | Yield Analysis | Minimum
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	1.0
Level III | EBITDA Multiple | Yield Analysis | Maximum
Level III investments and other financial instruments by valuation methodologies
Credit, measurement input	28.6
Level III | Private Equity
Level III investments and other financial instruments by valuation methodologies
Private equity, fair value	$ 10,510,089,000
Level III | Private Equity | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.071
Level III | Private Equity | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.050
Level III | Private Equity | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.150
Level III | Private Equity | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.271
Level III | Private Equity | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.000
Level III | Private Equity | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	1.000
Level III | Private Equity | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.599
Level III | Private Equity | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.000
Level III | Private Equity | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	1.000
Level III | Private Equity | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.130
Level III | Private Equity | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.000
Level III | Private Equity | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	1.000
Level III | Private Equity | Enterprise Value/LTM EBITDA Multiple | Market comparables | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	16.0
Level III | Private Equity | Enterprise Value/LTM EBITDA Multiple | Market comparables | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	8.2
Level III | Private Equity | Enterprise Value/LTM EBITDA Multiple | Market comparables | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	24.6
Level III | Private Equity | Enterprise Value/Forward EBITDA Multiple | Market comparables | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	15.4
Level III | Private Equity | Enterprise Value/Forward EBITDA Multiple | Market comparables | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	6.5
Level III | Private Equity | Enterprise Value/Forward EBITDA Multiple | Market comparables | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	20.6
Level III | Private Equity | Weighted Average Cost of Capital | Discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.096
Level III | Private Equity | Weighted Average Cost of Capital | Discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.064
Level III | Private Equity | Weighted Average Cost of Capital | Discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.182
Level III | Private Equity | Enterprise Value/LTM EBITDA Exit Multiple | Discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	13.1
Level III | Private Equity | Enterprise Value/LTM EBITDA Exit Multiple | Discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	6.0
Level III | Private Equity | Enterprise Value/LTM EBITDA Exit Multiple | Discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	17.5
Level III | Growth Equity
Level III investments and other financial instruments by valuation methodologies
Private equity, fair value	$ 2,116,890,000
Level III | Growth Equity | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.113
Level III | Growth Equity | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.100
Level III | Growth Equity | Illiquidity Discount | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.200
Level III | Growth Equity | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.413
Level III | Growth Equity | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.000
Level III | Growth Equity | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	1.000
Level III | Growth Equity | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.107
Level III | Growth Equity | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.000
Level III | Growth Equity | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.500
Level III | Growth Equity | Weight Ascribed to Milestones | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.480
Level III | Growth Equity | Weight Ascribed to Milestones | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.000
Level III | Growth Equity | Weight Ascribed to Milestones | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	1.000
Level III | Growth Equity | Base | Scenario Weighting | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.598
Level III | Growth Equity | Base | Scenario Weighting | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.250
Level III | Growth Equity | Base | Scenario Weighting | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.700
Level III | Growth Equity | Downside | Scenario Weighting | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.129
Level III | Growth Equity | Downside | Scenario Weighting | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.050
Level III | Growth Equity | Downside | Scenario Weighting | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.750
Level III | Growth Equity | Upside | Scenario Weighting | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.273
Level III | Growth Equity | Upside | Scenario Weighting | Minimum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.000
Level III | Growth Equity | Upside | Scenario Weighting | Maximum
Level III investments and other financial instruments by valuation methodologies
Private equity, measurement input	0.450
Level III | Energy
Level III investments and other financial instruments by valuation methodologies
Real assets, fair value	$ 1,728,637,000
Level III | Energy | Discounted cash flow | Liquids
Level III investments and other financial instruments by valuation methodologies
Revenue ratio of liquids	83.00%
Level III | Energy | Discounted cash flow | Natural Gas
Level III investments and other financial instruments by valuation methodologies
Revenue ratio of natural gas	17.00%
Level III | Energy | Weighted Average Cost of Capital | Discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.106
Level III | Energy | Weighted Average Cost of Capital | Discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.091
Level III | Energy | Weighted Average Cost of Capital | Discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.145
Level III | Energy | Average Price Per BOE | Discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input, value	$ 32.09
Level III | Energy | Average Price Per BOE | Discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input | $ / barrel	25.21
Level III | Energy | Average Price Per BOE | Discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input | $ / barrel	34.88
Level III | Infrastructure
Level III investments and other financial instruments by valuation methodologies
Real assets, fair value	$ 743,212,000
Level III | Infrastructure | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.065
Level III | Infrastructure | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.000
Level III | Infrastructure | Weight Ascribed to Market Comparables | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.250
Level III | Infrastructure | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.196
Level III | Infrastructure | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.000
Level III | Infrastructure | Weight Ascribed to Discounted Cash Flow | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.750
Level III | Infrastructure | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.739
Level III | Infrastructure | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.000
Level III | Infrastructure | Weight Ascribed to Transaction Price | Inputs to market comparables, discounted cash flow and transaction price | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	1.000
Level III | Real Estate
Level III investments and other financial instruments by valuation methodologies
Real assets, fair value	$ 1,968,256,000
Level III | Real Estate | Weight Ascribed to Discounted Cash Flow | Inputs to direct income capitalization and discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.767
Level III | Real Estate | Weight Ascribed to Discounted Cash Flow | Inputs to direct income capitalization and discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.000
Level III | Real Estate | Weight Ascribed to Discounted Cash Flow | Inputs to direct income capitalization and discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	1.000
Level III | Real Estate | Weight Ascribed to Direct Income Capitalization | Inputs to direct income capitalization and discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.233
Level III | Real Estate | Weight Ascribed to Direct Income Capitalization | Inputs to direct income capitalization and discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.000
Level III | Real Estate | Weight Ascribed to Direct Income Capitalization | Inputs to direct income capitalization and discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	1.000
Level III | Real Estate | Current Capitalization Rate | Direct income capitalization | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.058
Level III | Real Estate | Current Capitalization Rate | Direct income capitalization | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.043
Level III | Real Estate | Current Capitalization Rate | Direct income capitalization | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.078
Level III | Real Estate | Unlevered Discount Rate | Discounted cash flow | Weighted Average
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.071
Level III | Real Estate | Unlevered Discount Rate | Discounted cash flow | Minimum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.049
Level III | Real Estate | Unlevered Discount Rate | Discounted cash flow | Maximum
Level III investments and other financial instruments by valuation methodologies
Real assets, measurement input	0.180