Insurance (Insurance Liabilities Assumptions and Ratios - Narrative) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Future Policy Benefits and Policyholder Contract Deposits, Assumptions [Abstract]
Participating business as a percentage of gross life insurance policies in-force	3.00%	3.00%
Participating business as a percentage of the gross life insurance premiums	15.00%	14.00%	15.00%
Domestic Business | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate range credited to policyholder account balances	1.00%
Domestic Business | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate range credited to policyholder account balances	8.00%
Domestic Business | Participating Life Insurance Policies | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	3.00%
Domestic Business | Participating Life Insurance Policies | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	7.00%
Domestic Business | Nonparticipating Life Insurance Policies | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	2.00%
Domestic Business | Nonparticipating Life Insurance Policies | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	11.00%
Domestic Business | Individual and Group Traditional Fixed annuities [Member] | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	1.00%
Domestic Business | Individual and Group Traditional Fixed annuities [Member] | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	11.00%
Domestic Business | Non-medical Health Insurance [Member] | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	1.00%
Domestic Business | Non-medical Health Insurance [Member] | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	7.00%
Domestic Business | Group Long-Term Disability | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	2.00%
Domestic Business | Group Long-Term Disability | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	8.00%
International Business | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate range credited to policyholder account balances	1.00%
International Business | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate range credited to policyholder account balances	17.00%
International Business | Participating Life Insurance Policies | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	1.00%
International Business | Participating Life Insurance Policies | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	13.00%
International Business | Nonparticipating Life Insurance Policies | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	1.00%
International Business | Nonparticipating Life Insurance Policies | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	13.00%
International Business | Individual and Group Traditional Fixed annuities [Member] | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	1.00%
International Business | Individual and Group Traditional Fixed annuities [Member] | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	11.00%
International Business | Group Long-Term Disability | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	1.00%
International Business | Group Long-Term Disability | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest rate assumptions for the aggregate future policy benefit liabilities for traditional life insurance policies	9.00%