Deferred Policy Acquisition Costs - Progression of deferred policy acquisition costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
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	$ 1,239	$ 1,184
Deferred policy acquisition costs and present value of future profits, additions	207	205
Deferred policy acquisition costs and present value of future profits, periodic amortization	(185)	(166)
Deferred policy acquisition costs and present value of future profits, change included in realized gains	2	2
Deferred policy acquisition costs and present value of future profits, foreign currency translation	1
Deferred policy acquisition costs and present value of future profits, change in unrealized	(59)	(170)
Deferred policy acquisition costs and present value of future profits, ending balance	1,205	1,055
P&C
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs, beginning balance	238	226
Deferred policy acquisition costs, additions	139	132
Deferred policy acquisition costs, periodic amortization	(135)	(134)
Deferred policy acquisition costs, foreign currency translation	1
Deferred policy acquisition costs, ending balance	243	224
Annuity and Run-off Long-term Care and Life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs, beginning balance	1,110	1,018
Deferred policy acquisition costs, additions	67	68
Deferred policy acquisition costs, periodic amortization	(42)	(25)
Deferred policy acquisition costs, change included in realized gains	2	2
Deferred policy acquisition costs, ending balance	1,137	1,063
Movement in Deferred Sales Inducements [Roll Forward]
Deferred sales inducements, beginning balance	110	119
Deferred sales inducements, additions	1	5
Deferred sales inducements, periodic amortization	(6)	(5)
Deferred sales inducements, change included in realized gains	0	0
Deferred sales inducements, ending balance	105	119
Movement in Present Value of Future Insurance Profits [Roll Forward]
Present value of future profits, beginning balance	46	55
Present value of future profits, periodic amortization	(2)	(2)
Present value of future profits, ending balance	44	53
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	(265)	(234)
Unrealized investment gains (losses), change in unrealized	(59)	(170)
Unrealized investment gains (losses), ending balance	(324)	(404)
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	1,001	958
Deferred policy acquisition costs and present value of future profits, additions	68	73
Deferred policy acquisition costs and present value of future profits, periodic amortization	(50)	(32)
Deferred policy acquisition costs and present value of future profits, change included in realized gains	2	2
Deferred policy acquisition costs and present value of future profits, change in unrealized	(59)	(170)
Deferred policy acquisition costs and present value of future profits, ending balance	962	831
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	1,266	1,192
Deferred policy acquisition costs and present value of future profits, change in unrealized	0	0
Deferred policy acquisition costs and present value of future profits, ending balance	$ 1,286	$ 1,235