Contingencies, Commitments and Guarantees (Commitments and Guarantees - Narrative) (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Cumulative maximum indemnities and guarantees contractual limitation	$ 127,000,000
Liabilities for indemnities, guarantees and commitments	1,000,000	$ 1,000,000
Minimum
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	0
Indemnities and guarantees contractual limitation range	6,000,000
Maximum
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	10,000,000
Indemnities and guarantees contractual limitation range	122,000,000
Mortgage Loan Commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	325,000,000	206,000,000
Commitments to Fund Partnership Investments and Private Corporate Bond Investments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 1,700,000,000	$ 1,800,000,000

The range of the contractual limitation for guarantees and indemnities.

No definition available.

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- Definition

The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

No definition available.

+ Details

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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

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12069-110248

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12069-110248

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- Definition

The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 05
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99385795&loc=d3e12631-108344

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