Loans Receivable - Schedule of fair values and risk ratings (Details) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2025	Jun. 30, 2025 USD ($) loan	Dec. 31, 2024 USD ($) loan
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		21	23
Fair Value \| $		$ 849.1	$ 877.8
Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		100.00%	100.00%
BBB+
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		0	2
Fair Value \| $		$ 0.0	$ 199.0
BBB+ \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		0.00%	22.70%
BBB
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		3	1
Fair Value \| $		$ 280.8	$ 131.5
BBB \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		33.10%	15.00%
BBB-
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		0	1
Fair Value \| $		$ 0.0	$ 45.3
BBB- \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		0.00%	5.20%
BB+
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		1	0
Fair Value \| $		$ 99.1	$ 0.0
BB+ \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value	0.00%	11.70%
BB
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		0	1
Fair Value \| $		$ 0.0	$ 54.7
BB \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		0.00%	6.20%
BB-
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		2	1
Fair Value \| $		$ 160.8	$ 33.1
BB- \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		18.90%	3.80%
B+
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		2	0
Fair Value \| $		$ 71.6	$ 0.0
B+ \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		8.40%	0.00%
B
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		1	3
Fair Value \| $		$ 88.2	$ 231.6
B \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		10.40%	26.40%
CCC+
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		1	1
Fair Value \| $		$ 40.5	$ 17.5
CCC+ \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		4.80%	2.00%
CCC
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		0	1
Fair Value \| $		$ 0.0	$ 40.5
CCC \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		0.00%	4.60%
CCC-
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		1	0
Fair Value \| $		$ 28.5	$ 0.0
CCC- \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		3.30%	0.00%
CC
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		1	0
Fair Value \| $		$ 9.4	$ 0.0
CC \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value	0.00%	1.10%
C
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		0	1
Fair Value \| $		$ 0.0	$ 26.7
C \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		0.00%	3.00%
D
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		5	6
Fair Value \| $		$ 0.0	$ 0.0
D \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		0.00%	0.00%
NR
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans \| loan		4	5
Fair Value \| $		$ 70.2	$ 97.9
NR \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
% of Fair Value		8.30%	11.10%