Fair Value Measurements (Details) - Changes in Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	$ 201	$ 121
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	5	(1)
Level 3 fair value category, total unrealized investment gains (losses) reported in increases in other comprehensive income (loss)	(3)	2
Level 3 fair value category purchases	534	95
Level 3 fair value category sales	0	(1)
Level 3 fair value category settlements/maturities	(48)	(15)
Gross transfers into Level 3	0	3
Gross transfers out of Level 3	(93)	(3)
Level 3 fair value category, ending balance	596	201
Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	6	0
Fixed maturities [Member]
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	166	101
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	(1)	(1)
Level 3 fair value category, total unrealized investment gains (losses) reported in increases in other comprehensive income (loss)	(3)	2
Level 3 fair value category purchases	227	79
Level 3 fair value category sales	0	0
Level 3 fair value category settlements/maturities	(48)	(15)
Gross transfers into Level 3	0	3
Gross transfers out of Level 3	(93)	(3)
Level 3 fair value category, ending balance	248	166
Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	0	0
Equity securities [Member]
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	31	13
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	5	2
Level 3 fair value category, total unrealized investment gains (losses) reported in increases in other comprehensive income (loss)	0	0
Level 3 fair value category purchases	307	16
Level 3 fair value category sales	0	0
Level 3 fair value category settlements/maturities	0	0
Gross transfers into Level 3	0	0
Gross transfers out of Level 3	0	0
Level 3 fair value category, ending balance	343	31
Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	5	2
Other investments [Member]
Changes in Level 3 fair value category [Roll Forward]
Level 3 fair value category, beginning balance	4	7
Level 3 fair value category, total realized and unrealized investment gains (losses) reported in net realized investment gains	1	(2)
Level 3 fair value category, total unrealized investment gains (losses) reported in increases in other comprehensive income (loss)	0	0
Level 3 fair value category purchases	0	0
Level 3 fair value category sales	0	(1)
Level 3 fair value category settlements/maturities	0	0
Gross transfers into Level 3	0	0
Gross transfers out of Level 3	0	0
Level 3 fair value category, ending balance	5	4
Amount of total realized investment gains (losses) for the period included in the consolidated statement of income attributable to changes in the fair value of assets still held at the reporting date	$ 1	$ (2)