Schedule IV Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	$ 42,931	$ 43,425	$ 43,984
Ceded to Other Companies	8,360	8,979	10,134
Assumed from Other Companies	2,979	3,419	4,319
Net Amount	$ 37,550	$ 37,865	$ 38,169
Percent of Amount Assumed to Net	7.90%	9.00%	11.30%
Reportable Segments | Non-life insurance companies
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	$ 37,698	$ 39,375	$ 39,833
Ceded to Other Companies	7,604	8,318	9,514
Assumed from Other Companies	2,972	3,399	4,306
Net Amount	$ 33,066	$ 34,456	$ 34,625
Percent of Amount Assumed to Net	9.00%	9.90%	12.40%
Reportable Segments | Life insurance companies
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	$ 5,227	$ 4,039	$ 4,142
Ceded to Other Companies	756	661	620
Assumed from Other Companies	7	20	13
Net Amount	$ 4,478	$ 3,398	$ 3,535
Percent of Amount Assumed to Net	0.20%	0.60%	0.40%
Run-off Insurance Lines
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount	$ 6	$ 11	$ 9
Net Amount	6	11	9
Long-duration insurance in force
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Amount, Long-duration insurance in force	1,051,571	1,033,281	946,743
Long-duration insurance in force ceded	177,025	180,178	122,012
Contracts in Force Assumed	372	410	427
Net Amount, Long-duration insurance in force	874,918	$ 853,513	$ 825,158
Percent of Amount Assumed to Net		0.00%	0.10%
Ceded to Other Companies	177,025	$ 180,178	$ 122,012
Assumed from Other Companies	372	410	427
Net Amount	$ 874,918	$ 853,513	$ 825,158
Percent of Amount Assumed to Net	0.00%	0.00%	0.10%