KWE Unsecured Bonds - Schedule of KWE Unsecured Bonds (Details) - KWE unsecured bonds - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total debt	$ 516.4	$ 506.4
KWE
Debt Instrument [Line Items]
Unamortized loan fees	(0.7)	(0.7)
Total debt	516.4	506.4
Unamortized discount (premium)	1.2	1.5
KWE | KWE Euro Medium Term Note Programme
Debt Instrument [Line Items]
Mortgage debt (excluding loan fees)	$ 517.1	$ 507.1