KW Unsecured Debt - Borrowings Under Credit Facilities (Details) - A&R Facility [Member]		9 Months Ended
	Mar. 25, 2020 USD ($)	Sep. 30, 2020 USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing capacity and debt instrument, face amount		$ 700,000,000
Line of Credit [Member] | Revolving Credit Facility [Member]
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	1.50
Maximum amount outstanding during period		200,000,000.0
Remaining borrowing capacity		300,000,000.0
Average outstanding amount		128,500,000
Line of Credit [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Fixed charge coverage ratio	1.70
Tangible net worth	$ 1,700,000,000
Liquidity	$ 75,000,000.0
Line of Credit [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Secured recourse leverage ratio	3.50%
Liquidity	$ 299,000,000
Adjusted secured leverage ratio	55.00%
Line of Credit [Member] | Revolving Credit Facility [Member] | LIBOR [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate (as percent)	1.75%
Line of Credit [Member] | Revolving Credit Facility [Member] | LIBOR [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate (as percent)	2.50%
Medium-term Notes [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 200,000,000