Loans Receivable - Scheduled of loans receivable by property type (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Outstanding		$ 1,658.6	$ 1,504.1
Fair Value		$ 1,548.5	$ 1,492.6
Credit Concentration Risk | Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of Fair Value	100.00%	100.00%	100.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Outstanding		$ 897.7	$ 862.4
Fair Value		$ 790.8	853.4
Office | Credit Concentration Risk | Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of Fair Value	57.20%	51.10%
Apartments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Outstanding		$ 258.9	253.3
Fair Value		$ 256.2	252.0
Apartments | Credit Concentration Risk | Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of Fair Value	16.90%	16.50%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Outstanding		$ 131.6	161.4
Fair Value		$ 131.1	161.3
Industrial | Credit Concentration Risk | Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of Fair Value	10.80%	8.50%
Hotel
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Outstanding		$ 125.3	125.3
Fair Value		$ 125.3	125.3
Hotel | Credit Concentration Risk | Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of Fair Value	8.40%	8.10%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Outstanding		$ 245.1	101.7
Fair Value		$ 245.1	$ 100.6
Retail | Credit Concentration Risk | Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of Fair Value	6.70%	15.80%