Policyholders' Liabilities (Policyholders' Account Balances) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Liability for Policyholders' Account Balance, by Product Segment [Line Items]
Total policyholders’ account balances	$ 152,110	$ 150,338
Individual annuities
Liability for Policyholders' Account Balance, by Product Segment [Line Items]
Total policyholders’ account balances	44,391	43,309
Group annuities
Liability for Policyholders' Account Balance, by Product Segment [Line Items]
Total policyholders’ account balances	27,843	27,618
Guaranteed investment contracts and guaranteed interest accounts
Liability for Policyholders' Account Balance, by Product Segment [Line Items]
Total policyholders’ account balances	13,759	13,558
Funding agreements
Liability for Policyholders' Account Balance, by Product Segment [Line Items]
Total policyholders’ account balances	4,119	3,785
Interest-sensitive life contracts
Liability for Policyholders' Account Balance, by Product Segment [Line Items]
Total policyholders’ account balances	40,364	39,228
Dividend accumulation and other deposit type funds
Liability for Policyholders' Account Balance, by Product Segment [Line Items]
Total policyholders’ account balances	$ 21,634	$ 22,840