Deferred Policy Acquisition Costs - Progression of deferred policy acquisition costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Deferred policy acquisition costs and present value of future profits, beginning balance	$ 881	$ 965	$ 1,184	$ 821
Deferred policy acquisition costs and present value of future profits, additions	181	215	583	567
Deferred policy acquisition costs and present value of future profits, periodic amortization	(185)	(177)	(519)	(537)
Deferred policy acquisition costs and present value of future profits, change included in realized gains	1	3	6	7
Deferred policy acquisition costs and present value of future profits, foreign currency translation	(1)	(2)	(2)	(2)
Deferred policy acquisition costs and present value of future profits, change in unrealized	(10)	(11)	(385)	137
Deferred policy acquisition costs and present value of future profits, ending balance	867	993	867	993
P&C
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs, beginning balance	234	223	226	221
Deferred policy acquisition costs, additions	132	138	403	396
Deferred policy acquisition costs, periodic amortization	(134)	(132)	(396)	(388)
Deferred policy acquisition costs, foreign currency translation	(1)	(2)	(2)	(2)
Deferred policy acquisition costs, ending balance	231	227	231	227
Annuity and Run-off Long-term Care and Life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs, beginning balance	1,089	934	1,018	925
Deferred policy acquisition costs, additions	48	74	172	164
Deferred policy acquisition costs, periodic amortization	(42)	(36)	(99)	(120)
Deferred policy acquisition costs, change included in realized gains	1	3	5	6
Deferred policy acquisition costs, ending balance	1,096	975	1,096	975
Movement in Deferred Sales Inducements [Roll Forward]
Deferred sales inducements, beginning balance	116	123	119	132
Deferred sales inducements, additions	1	3	8	7
Deferred sales inducements, periodic amortization	(6)	(6)	(17)	(20)
Deferred sales inducements, change included in realized gains	0	0	1	1
Deferred sales inducements, ending balance	111	120	111	120
Movement in Present Value of Future Insurance Profits [Roll Forward]
Present value of future profits, beginning balance	51	68	55	74
Present value of future profits, periodic amortization	(3)	(3)	(7)	(9)
Present value of future profits, ending balance	48	65	48	65
Movement in Unrealized Gains (Losses) Related to Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Unrealized investment gains (losses), beginning balance	(609)	(383)	(234)	(531)
Unrealized investment gains (losses), change in unrealized	(10)	(11)	(385)	137
Unrealized investment gains (losses), ending balance	(619)	(394)	(619)	(394)
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Deferred policy acquisition costs and present value of future profits, beginning balance	647	742	958	600
Deferred policy acquisition costs and present value of future profits, additions	49	77	180	171
Deferred policy acquisition costs and present value of future profits, periodic amortization	(51)	(45)	(123)	(149)
Deferred policy acquisition costs and present value of future profits, change included in realized gains	1	3	6	7
Deferred policy acquisition costs and present value of future profits, change in unrealized	(10)	(11)	(385)	137
Deferred policy acquisition costs and present value of future profits, ending balance	636	766	636	766
Excluding Unrealized Gains | Annuity and Run-off Long-term Care and Life
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Deferred policy acquisition costs and present value of future profits, beginning balance	1,256	1,125	1,192	1,131
Deferred policy acquisition costs and present value of future profits, change in unrealized	0	0	0	0
Deferred policy acquisition costs and present value of future profits, ending balance	$ 1,255	$ 1,160	$ 1,255	$ 1,160