Commitments and Contingent Liabilities (Narratives) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Commitments and Contingent Liabilities [Line Items]
Litigation and regulatory matters loss contingency, range of possible loss, maximum (less than)	$ 10.0	$ 10.0
Commitments \| Commercial Mortgage Loans
Commitments and Contingent Liabilities [Line Items]
Total outstanding mortgage loan commitments	1.0	1.0	$ 4.0
Allowance for credit losses	0.0	0.0
Change in allowance for credit losses	0.0	0.0
Commitments \| Investments
Commitments and Contingent Liabilities [Line Items]
Commitments to Purchase Investment (excluding Commercial Mortgage Loans)	63.0	63.0	$ 48.0
Purchase Commitment
Commitments and Contingent Liabilities [Line Items]
Change in allowance for credit losses	$ 0.0	$ 0.0

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12021-110248

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- Definition

Amount of investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Column G))
-URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014

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- Definition

Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121611286&loc=d3e11927-110247

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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- Definition

Amount of expense (reversal of expense) for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
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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

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

+ References

No definition available.

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