Reinsurance (Reinsurance Recoverable by Category and Listing of Largest Reinsurers) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
2012	$ 11,617
Provision	390	439
% of Gross	3.40%
Largest reinsurers
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
2012	5,117
Provision	78
% of Gross	1.50%
Other reinsurers balances rated A- or better
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
2012	2,901
Provision	36
% of Gross	1.20%
Other reinsurers balances with ratings lower than A- or not rated
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
2012	587
Provision	103
% of Gross	17.50%
Other pools and government agencies
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
2012	338
Provision	21
% of Gross	6.20%
Structured settlements
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
2012	577
Provision	12
% of Gross	2.10%
Other captives
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
2012	1,762
Provision	14
% of Gross	0.80%
Other
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
2012	335
Provision	$ 126
% of Gross	37.60%