Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Data (Unaudited) [Abstract]
Total revenues	$ 3,709		$ 3,465		$ 2,310		$ 3,099		$ 3,876		$ 3,675		$ 3,623		$ 3,757		$ 12,583	$ 14,931	$ 14,066
Net income (loss)	$ 397	[1],[2],[3]	$ 139	[1],[2],[3]	$ (835)	[1],[2],[3]	$ (632)	[1],[2],[3]	$ 217	[4],[5]	$ 72	[4],[5]	$ 249	[4],[5]	$ 394	[4],[5]	$ (931)	$ 932	$ 636
Per share-basic (in dollars per share)	$ 1.45		$ 0.50		$ (2.96)		$ (2.20)		$ 0.73		$ 0.24		$ 0.82		$ 1.27		$ (3.32)	$ 3.08	$ 1.99
Per share-diluted (in dollars per share)	$ 1.45		$ 0.50		$ (2.96)		$ (2.20)		$ 0.73		$ 0.24		$ 0.82		$ 1.27		$ (3.32)	$ 3.07	$ 1.99
Premium deficiency in long term future policy benefit reserves, after tax and noncontrolling interests			$ 52								$ 151
Net catastrophe losses, after tax and noncontrolling interests			$ (112)		$ (212)
Deconsolidation loss, after tax					$ (957)
Asset impairment charge, after tax and noncontrolling interests							$ 408
Net investment income, after tax and noncontrolling interests									$ 116
Asset impairment charge, after tax									$ 69

[1] Net income for the third quarter of 2020 included net catastrophe losses of $112 million (after tax and noncontrolling interests) and a $52 million (after tax and noncontrolling interests) charge related to the recognition of an active life reserve premium deficiency as a result of the third quarter GPV.

[2] Net loss for the first quarter of 2020 included an aggregate asset impairment charge of $408 million (after tax and noncontrolling interests) related to Diamond Offshore drilling rigs.

[3] Net loss for the second quarter of 2020 included an investment loss of $957 million (after tax) related to the deconsolidation of Diamond Offshore and net catastrophe losses of $212 million (after tax and noncontrolling interests).

[4] Net income for the fourth quarter of 2019 included net investment income of $116 million (after tax and noncontrolling interests) related to limited partnerships and equity securities partially offset by asset impairment charges of $69 million (after tax).

[5] Net income for the third quarter of 2019 included a $151 million (after tax and noncontrolling interests) charge related to the recognition of an active life reserve premium deficiency as a result of the third quarter GPV.