Loans Receivable - Schedule of fair values and risk ratings (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans	27
Fair Value \| $	$ 1,572.1	$ 913.0
Percentage	100.00%
Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage	100.00%	100.00%
AA
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans	1
Fair Value \| $	$ 48.3
AA \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage	3.10%
BBB
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans	7
Fair Value \| $	$ 456.1
BBB \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage	29.00%
BB
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans	13
Fair Value \| $	$ 787.4
BB \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage	50.10%
B
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans	3
Fair Value \| $	$ 205.0
B \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage	13.00%
NR
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans	3
Fair Value \| $	$ 75.3
NR \| Loans Receivable \| Credit Concentration Risk
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage	4.80%
Related Party
Financing Receivable, Credit Quality Indicator [Line Items]
Number of loans collateralized by interest in a joint venture	2
Unaffiliated Entity
Financing Receivable, Credit Quality Indicator [Line Items]
Number of loans collateralized by interest in a joint venture	1

Loans Receivable, Number Of Loans

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- Definition

Loans Receivable, Number Of Loans Collateralized By Interest In Joint Venture

+ References

No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

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