Investments (Mortgage Loans - Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) Contracts	Dec. 31, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ 944	$ 867
Financing Receivable, Purchase	3,300	4,800	$ 3,500
Mortgage Loans, Gross	84,344	80,635
Financing Receivable, after Allowance for Credit Loss	$ 83,919	$ 80,470
Percentage of Mortgage Loans Classified as Performing	99.00%	99.00%
Nonaccrual	$ 1,117	$ 731
Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Outstanding Balance		3,300
Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Carrying Amount, Net		2,700
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Accretion		178	275
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of mortgage loans with LTV ratio in excess of 100%	1.00%
Mortgage Loans with LTV ratio in excess of 100% [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans, Gross	$ 650
Financing Receivable, after Allowance for Credit Loss	0
Commercial Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Receivable	209	188
Deferred mortgage loan interest and principal payments due to COVID-19	66
Mortgage Loans, Gross	52,434	49,624
Nonaccrual	317	176	176
Financing Receivable, Nonaccrual, No Allowance	168	0
Residential Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Receivable	108	$ 94
Deferred mortgage loan interest and principal payments due to COVID-19	37
Financing Receivable, Modifications, Number of Contracts \| Contracts		396
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 97
Financing Receivable, Troubled Debt Restructuring, Postmodification		87
Mortgage Loans, Gross	13,782	14,316
Nonaccrual	534	418	436
Financing Receivable, Nonaccrual, No Allowance	0	0
Agricultural Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Receivable	174	$ 186
Deferred mortgage loan interest and principal payments due to COVID-19	6
Financing Receivable, Modifications, Number of Contracts \| Contracts		3
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 111
Financing Receivable, Troubled Debt Restructuring, Postmodification		111
Mortgage Loans, Gross	18,128	16,695
Nonaccrual	266	137	$ 105
Financing Receivable, Nonaccrual, No Allowance	$ 178	$ 93

Deferred commercial mortgage loan interest and principal payments due to COVID-19

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

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The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and other-than-temporary impairments), for certain contractual rights to receive money on demand or on fixed or determinable dates. This relates to loans accounted for as available-for-sale debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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