Schedule III Supplementary Insurance Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplementary Insurance Information, by Segment [Line Items]
Deferred Policy Acquisition Costs	$ 10,994	$ 11,042
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	123,825	119,281
Unearned Premiums	19,030	19,634
Policy and Contract Claims	860	847
Premiums and Policy Fees	34,309	37,125	$ 39,410
Net Investment Income	14,179	14,065	14,053
Losses and Loss Expenses Incurred, Benefits	33,564	36,142	35,076
Amortization of Deferred Policy Acquisition Costs	4,288	4,521	5,236
Other Operating Expenses	7,396	8,667	10,455
Net Premiums Written	25,756	29,233	33,066
General Insurance
Supplementary Insurance Information, by Segment [Line Items]
Deferred Policy Acquisition Costs	2,587	2,563
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	73,530	71,926
Unearned Premiums	18,795	19,348
Policy and Contract Claims	0	0
Premiums and Policy Fees	26,026	29,586	30,922
Net Investment Income	3,668	3,554	3,746
Losses and Loss Expenses Incurred, Benefits	21,642	25,103	22,873
Amortization of Deferred Policy Acquisition Costs	3,765	4,121	4,319
Other Operating Expenses	5,100	5,967	6,848
Net Premiums Written	25,438	28,393	32,199
Life and Retirement
Supplementary Insurance Information, by Segment [Line Items]
Deferred Policy Acquisition Costs	8,407	8,466
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	44,615	41,383
Unearned Premiums	0	0
Policy and Contract Claims	851	836
Premiums and Policy Fees	6,844	4,878	5,677
Net Investment Income	7,816	7,622	7,541
Losses and Loss Expenses Incurred, Benefits	8,607	6,945	7,745
Amortization of Deferred Policy Acquisition Costs	743	613	794
Other Operating Expenses	2,296	2,700	3,607
Net Premiums Written	0	0	0
Other Operations
Supplementary Insurance Information, by Segment [Line Items]
Deferred Policy Acquisition Costs	0	13
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	5,680	5,972
Unearned Premiums	235	286
Policy and Contract Claims	9	11
Premiums and Policy Fees	712	1,845	1,641
Net Investment Income	(81)	(24)	(162)
Losses and Loss Expenses Incurred, Benefits	1,076	743	854
Amortization of Deferred Policy Acquisition Costs	(296)	(321)	21
Other Operating Expenses	0	0	0
Net Premiums Written	314	819	668
Legacy Portfolio
Supplementary Insurance Information, by Segment [Line Items]
Premiums and Policy Fees	727	816	1,170
Net Investment Income	2,776	2,913	2,928
Losses and Loss Expenses Incurred, Benefits	2,239	3,351	3,604
Amortization of Deferred Policy Acquisition Costs	76	108	102
Other Operating Expenses	0	0	0
Net Premiums Written	$ 4	$ 21	$ 199