Reinsurance (Effect of Reinsurance on Life Insurance In Force) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reinsurance Disclosures [Abstract]
Reinsurance Premiums for Insurance Companies, by Product Segment, Gross Amount	$ 1,576	$ 1,686	$ 78
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Assumed from Other Companies	3,062,525	2,995,079	2,943,517
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	214,727	222,388	230,544
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 2,849,374	$ 2,774,377	$ 2,713,051
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	107.50%	108.00%	108.50%