Investments - Mortgage Loans, Residential by State (Details) - Geographic Concentration Risk - Residential mortgage loans - Mortgage Loans, Net	Jun. 30, 2020	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Percentage concentration risk	100.00%	100.00%
California
Loans and Leases Receivable Disclosure [Line Items]
Percentage concentration risk	36.50%	27.00%
Florida
Loans and Leases Receivable Disclosure [Line Items]
Percentage concentration risk	11.50%	12.70%
TEXAS
Loans and Leases Receivable Disclosure [Line Items]
Percentage concentration risk	4.40%	6.20%
Other U.S. States
Loans and Leases Receivable Disclosure [Line Items]
Percentage concentration risk	35.50%	41.70%
Total U.S. Region
Loans and Leases Receivable Disclosure [Line Items]
Percentage concentration risk	87.90%	87.60%
IRELAND
Loans and Leases Receivable Disclosure [Line Items]
Percentage concentration risk	11.90%	12.40%
International Other [Member]
Loans and Leases Receivable Disclosure [Line Items]
Percentage concentration risk	0.20%	0.00%

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13531-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13537-108611

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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