Policyholders' Liabilities (Narrative) (Details)	Dec. 31, 2018
Individual and group annuities and supplementary contracts
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Percentage of reserves based on interest rates in excess of 8 percent	1.00%
Individual and group annuities and supplementary contracts | Minimum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Future Policy Benefits, Interest Rate	0.00%
Individual and group annuities and supplementary contracts | Maximum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Future Policy Benefits, Interest Rate	8.30%
Other contract liabilities | Minimum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Future Policy Benefits, Interest Rate	3.10%
Other contract liabilities | Maximum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Future Policy Benefits, Interest Rate	4.40%
Interest-sensitive life contracts | Minimum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Policyholders Account Balances, Interest rate	3.50%
Interest-sensitive life contracts | Maximum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Policyholders Account Balances, Interest rate	6.00%
Individual annuities | Minimum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Policyholders Account Balances, Interest rate	0.00%
Individual annuities | Maximum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Policyholders Account Balances, Interest rate	6.50%
Guaranteed interest accounts | Minimum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Policyholders Account Balances, Interest rate	0.10%
Guaranteed interest accounts | Maximum
Liability for Future Policy Benefit and Policyholders' Account Balances, by Product Segment [Line Items]
Liability for Policyholders Account Balances, Interest rate	5.80%