Investments (Mortgage Loans - Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($) Contracts	Dec. 31, 2017 USD ($) Contracts	Dec. 31, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ 944	$ 1,100
Real Estate Acquired Through Foreclosure	45	48
Financing Receivable, Significant Purchases	3,500	3,100	$ 2,900
Impaired Financing Receivable, Average Recorded Investment	$ 481	$ 322
Percentage of Mortgage Loans Classified as Performing	99.00%	99.00%
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 358	$ 285	188
Financing Receivable, Net	12,700	11,600
Agricultural Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	123	32	49
Financing Receivable, Net	14,900	13,100
Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 0	$ 5	$ 90
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Contracts	0	0
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts \| Contracts	440	500
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 96	$ 120
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 92	$ 108

The percentage of all mortgage loans that are classified as performing.

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Number of financing receivables that have been modified by troubled debt restructurings.

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Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

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Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

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The amount of any significant purchases of financing receivables during the reporting period.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

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Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

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-Publisher FASB
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Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

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