KW UNSECURED DEBT - Borrowings Under Credit Facilities (Details) - USD ($)		12 Months Ended
	Mar. 25, 2020	Dec. 31, 2020	Feb. 17, 2021	Dec. 31, 2019
Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt (excluding loan fees)		$ 200,000,000.0		$ 0
A&R Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity and debt instrument, face amount		700,000,000
A&R Facility | Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 500,000,000	500,000,000
Maturity of extension	1 year
Maximum consolidated leverage ratio	65.00%
Fixed charge coverage ratio measurement period	12 months
Covenant, percent of new equity offerings	50.00%
Maximum secured recourse leverage multiplier	1.5
Remaining borrowing capacity		300,000,000.0
Average outstanding amount		146,400,000
A&R Facility | Line of Credit | Revolving Credit Facility | Subsequent Event
Line of Credit Facility [Line Items]
Debt (excluding loan fees)			$ 100,000,000.0
Remaining borrowing capacity			$ 400,000,000.0
A&R Facility | Line of Credit | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Fixed charge coverage ratio	1.70
Tangible net worth	$ 1,700,000,000
Liquidity	$ 75,000,000.0
A&R Facility | Line of Credit | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Secured recourse leverage ratio	3.50%
Liquidity	$ 299,000,000
Adjusted secured leverage ratio	55.00%
A&R Facility | Line of Credit | Revolving Credit Facility | LIBOR | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate (as percent)	1.75%
A&R Facility | Line of Credit | Revolving Credit Facility | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate (as percent)	2.50%
A&R Facility | Term Loan
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 200,000,000