EQUITY BASED COMPENSATION - Estimated Unrecognized Expense (Details) - USD ($) $ in Millions	Sep. 30, 2020	Nov. 30, 2016
KKR Holdings Principal Awards
Equity Based Payments
Estimated unrecognized equity-based payment expense	$ 87.1	$ 320.9
KKR Holdings Principal Awards | Remainder of 2020
Equity Based Payments
Estimated unrecognized equity-based payment expense	16.5
KKR Holdings Principal Awards | 2021
Equity Based Payments
Estimated unrecognized equity-based payment expense	44.8
KKR Holdings Principal Awards | 2022
Equity Based Payments
Estimated unrecognized equity-based payment expense	25.8
Equity Incentive Plans
Equity Based Payments
Estimated unrecognized equity-based payment expense	168.8
Equity Incentive Plans | Remainder of 2020
Equity Based Payments
Estimated unrecognized equity-based payment expense	31.6
Equity Incentive Plans | 2021
Equity Based Payments
Estimated unrecognized equity-based payment expense	86.4
Equity Incentive Plans | 2022
Equity Based Payments
Estimated unrecognized equity-based payment expense	39.7
Equity Incentive Plans | 2023
Equity Based Payments
Estimated unrecognized equity-based payment expense	9.1
Equity Incentive Plans | 2024
Equity Based Payments
Estimated unrecognized equity-based payment expense	1.7
Equity Incentive Plans | 2025
Equity Based Payments
Estimated unrecognized equity-based payment expense	$ 0.3