Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pre-tax
Other comprehensive income (loss)	$ 2,322	$ (1,094)	$ 481
Tax
Other comprehensive income (loss)	(490)	233	(169)
After-tax
Other comprehensive income (loss)	1,832	(861)	312
Unrealized net capital gains and losses
Pre-tax
Unrealized net holding during the period	2,807	(1,142)	866
Less: reclassification adjustment	413	(186)	374
Other comprehensive income (loss)	2,394	(956)	492
Tax
Unrealized net holding during the period	(592)	241	(304)
Less: reclassification adjustment	(87)	39	(131)
Other comprehensive income (loss)	(505)	202	(173)
After-tax
Unrealized net holding during the period	2,215	(901)	562
Less: reclassification adjustment	326	(147)	243
Other comprehensive income (loss)	1,889	(754)	319
Unrealized foreign currency translation adjustments
Pre-tax
Other comprehensive income (loss)	(13)	(61)	69
Tax
Other comprehensive income (loss)	3	13	(24)
After-tax
Other comprehensive income (loss)	(10)	(48)	45
Unamortized pension and other postretirement prior service credit
Pre-tax
Other comprehensive income (loss)	(59)	(77)	(80)
Tax
Other comprehensive income (loss)	12	18	28
After-tax
Other comprehensive income (loss)	$ (47)	$ (59)	$ (52)