Schedule IV Reinsurance (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	$ 43,425	$ 43,984	$ 44,604
Ceded to Other Companies	8,979	10,134	11,635
Assumed from Other Companies	3,419	4,319	4,917
Net Amount	37,865	38,169	37,886
Percent of Amount Assumed to Net	9.00%	11.30%	13.00%
Divested Businesses
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	11	9	11
Net Amount	11	9	11
Reportable Segments | Commercial Insurance
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	39,375	39,833	40,647
Ceded to Other Companies	8,318	9,514	11,054
Assumed from Other Companies	3,399	4,306	4,900
Net Amount	34,456	34,625	34,493
Percent of Amount Assumed to Net	9.90%	12.40%	14.20%
Reportable Segments | Consumer Insurance
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	4,039	4,142	3,946
Ceded to Other Companies	661	620	581
Assumed from Other Companies	20	13	17
Net Amount	3,398	3,535	3,382
Percent of Amount Assumed to Net	0.60%	0.40%	0.50%
Long-duration insurance in force
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount, Long-duration insurance in force	1,033,281	946,743	947,951
Long-duration insurance in force ceded	180,178	122,012	129,159
Contracts in Force Assumed	410	427	458
Net Amount, Long-duration insurance in force	$ 853,513	$ 825,158	$ 819,250
Percent of Amount Assumed to Net		0.10%	0.10%