Investments (Realized Investment Gains Losses Net) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gain (Loss) on Securities [Line Items]
Realized investment gains (losses), net	$ (459)	$ 1,977	$ 432
Fixed Maturities
Gain (Loss) on Securities [Line Items]
Realized investment gains (losses), net	966	228	581
Equity securities
Gain (Loss) on Securities [Line Items]
Realized investment gains (losses), net	0	0	1,066
Commercial mortgage and other loans
Gain (Loss) on Securities [Line Items]
Realized investment gains (losses), net	44	49	70
Investment Real Estate
Gain (Loss) on Securities [Line Items]
Realized investment gains (losses), net	78	84	12
LPs/LLCs
Gain (Loss) on Securities [Line Items]
Realized investment gains (losses), net	(38)	17	(23)
Derivatives
Gain (Loss) on Securities [Line Items]
Realized investment gains (losses), net	(1,513)	1,597	(1,275)
Other
Gain (Loss) on Securities [Line Items]
Realized investment gains (losses), net	$ 4	$ 2	$ 1