Schedule II-Condensed Financial Information of Registrant (Statement of Comprehensive Income) (Details) - USD ($) $ 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
Net income	$ 551	$ 222	$ 2,276	$ 1,523	$ 934	$ 1,183	$ 1,139	$ 1,551	$ 4,572	$ 4,807	$ 3,750
Other comprehensive income, net of tax:
Change in net unrealized gains/losses on investments									428	680	(418)
Change in non-credit component of impairment losses on investments net of tax									0	0	(2)
Change in net unrealized gains/losses on cash flow hedges									12	(16)	37
Change in net periodic pension and postretirement costs									(1)	26	(90)
Foreign currency translation adjustments									7	0	(1)
Other comprehensive income (loss)									446	690	(474)
Total comprehensive income									5,018	5,497	3,276
Parent Company [Member]
Net income									4,572	4,807	3,750
Other comprehensive income, net of tax:
Change in net unrealized gains/losses on investments									428	680	(418)
Change in non-credit component of impairment losses on investments net of tax									0	0	(2)
Change in net unrealized gains/losses on cash flow hedges									12	(16)	37
Change in net periodic pension and postretirement costs									(1)	26	(90)
Foreign currency translation adjustments									7	0	(1)
Other comprehensive income (loss)									446	690	(474)
Total comprehensive income									$ 5,018	$ 5,497	$ 3,276