BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Kennedy Wilson Europe Real Estate Plc ("KWE") Acquisition (Details) $ / shares in Units, £ in Millions, $ in Millions			12 Months Ended
	Oct. 20, 2017 USD ($) $ / shares shares	Oct. 20, 2017 GBP (£) shares	Dec. 31, 2017 shares	Dec. 31, 2019 $ / shares	Dec. 31, 2018 $ / shares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Par value (in dollars per share) | $ / shares	$ 0.0001			$ 0.001	$ 0.001
KWE [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Cash consideration to shareholders	$ 697.2	£ 528.6
Common Stock [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Issuance of common stock (in shares) | shares	37,226,695	37,226,695	37,226,695