Accumulated Other Comprehensive Income (Loss) by Component (Schedule of Accumulated Other Comprehensive Income (Loss) by Component) (Details) - USD ($) $ in Millions						3 Months Ended					6 Months Ended
		Dec. 31, 2022		Dec. 31, 2021		Jun. 30, 2023	Jun. 30, 2022		Mar. 31, 2022		Jun. 30, 2023	Jun. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period	[1]										$ 8,548
Other comprehensive income (loss) before reclassifications						$ (145)	$ (802)				120	$ (1,829)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax						(28)	(19)				(53)	(26)
Other comprehensive income (loss) after tax (expense) benefit						(117)	(783)				173	(1,803)
Total stockholder's equity at end of period		$ 8,548	[1]			8,726	9,005	[2]			8,726	9,005	[2]
Income tax effects allocated directly to equity, cumulative effect of change in accounting principle		11		$ (446)					$ (227)
Reclassification from AOCI, tax						8	3				14	6
Tax (expense) benefit on other comprehensive income (loss)						42	189				(33)	451
Prior to Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period											8,825
Total stockholder's equity at end of period		8,825
Effect of Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period											(277)
Total stockholder's equity at end of period		(277)
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period						(3,308)	(2,380)	[2]	(1,360)	[2]	(3,598)	(1,360)	[2]
Total stockholder's equity at end of period		(3,598)		(1,360)	[2]	(3,425)	(3,163)	[2]	(2,380)	[2]	(3,425)	(3,163)	[2]
Accumulated other comprehensive income (loss) | Prior to Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period						(3,308)	(1,303)	[2]	320	[2]	(3,557)	320	[2]
Total stockholder's equity at end of period		(3,557)		320	[2]				(1,303)	[2]
Accumulated other comprehensive income (loss) | Effect of Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period						0	(1,077)	[2]	(1,680)	[2]	(41)	(1,680)	[2]
Total stockholder's equity at end of period		(41)		(1,680)	[2]				(1,077)	[2]
Net unrealized gains (losses) on investments | Net unrealized gains (losses) on investments with an allowance for credit losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period						(15)	(6)		(2)		(7)	(2)
Other comprehensive income (loss) before reclassifications						(8)	(1)				(16)	(5)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax						(7)	1				(7)	1
Other comprehensive income (loss) after tax (expense) benefit						(1)	(2)				(9)	(6)
Total stockholder's equity at end of period		(7)		(2)		(16)	(8)		(6)		(16)	(8)
Income tax effects allocated directly to equity, cumulative effect of change in accounting principle		0		0					0
Reclassification from AOCI, tax						2	(1)				2	(1)
Tax (expense) benefit on other comprehensive income (loss)						0	0				2	1
Net unrealized gains (losses) on investments | Net unrealized gains (losses) on investments with an allowance for credit losses | Prior to Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							(6)		(2)		(7)	(2)
Total stockholder's equity at end of period		(7)		(2)					(6)
Net unrealized gains (losses) on investments | Net unrealized gains (losses) on investments with an allowance for credit losses | Effect of Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							0		0		0	0
Total stockholder's equity at end of period		0		0					0
Net unrealized gains (losses) on investments | Net unrealized gains (losses) on other investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period						(2,068)	716		3,359		(2,738)	3,359
Other comprehensive income (loss) before reclassifications						(427)	(2,240)				225	(4,884)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax						(14)	(14)				(32)	(15)
Other comprehensive income (loss) after tax (expense) benefit						(413)	(2,226)				257	(4,869)
Total stockholder's equity at end of period		(2,738)		3,359		(2,481)	(1,510)		716		(2,481)	(1,510)
Income tax effects allocated directly to equity, cumulative effect of change in accounting principle		0		617					270
Reclassification from AOCI, tax						4	3				8	4
Tax (expense) benefit on other comprehensive income (loss)						112	590				(68)	1,288
Net unrealized gains (losses) on investments | Net unrealized gains (losses) on other investments | Prior to Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							(572)		1,039		(2,738)	1,039
Total stockholder's equity at end of period		(2,738)		1,039					(572)
Net unrealized gains (losses) on investments | Net unrealized gains (losses) on other investments | Effect of Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							1,288		2,320		0	2,320
Total stockholder's equity at end of period		0		2,320					1,288
Pension and postretirement benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period						(584)	(598)		(604)		(591)	(604)
Other comprehensive income (loss) before reclassifications						0	0				0	0
Amounts reclassified from accumulated other comprehensive income (loss) net of tax						(7)	(6)				(14)	(12)
Other comprehensive income (loss) after tax (expense) benefit						7	6				14	12
Total stockholder's equity at end of period		(591)		(604)		(577)	(592)		(598)		(577)	(592)
Income tax effects allocated directly to equity, cumulative effect of change in accounting principle		0		0					0
Reclassification from AOCI, tax						2	1				4	3
Tax (expense) benefit on other comprehensive income (loss)						(2)	(1)				(4)	(3)
Pension and postretirement benefits | Prior to Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							(598)		(604)		(591)	(604)
Total stockholder's equity at end of period		(591)		(604)					(598)
Pension and postretirement benefits | Effect of Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							0		0		0	0
Total stockholder's equity at end of period		0		0					0
Cumulative impact of changes in discount rates used to measure long duration contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period						(437)	(2,365)		(4,000)		(41)	(4,000)
Other comprehensive income (loss) before reclassifications						256	1,507				(140)	3,142
Amounts reclassified from accumulated other comprehensive income (loss) net of tax						0	0				0	0
Other comprehensive income (loss) after tax (expense) benefit						256	1,507				(140)	3,142
Total stockholder's equity at end of period		(41)		(4,000)		(181)	(858)		(2,365)		(181)	(858)
Income tax effects allocated directly to equity, cumulative effect of change in accounting principle		11		(1,063)					(497)
Reclassification from AOCI, tax						0	0				0	0
Tax (expense) benefit on other comprehensive income (loss)						(68)	(400)				37	(835)
Cumulative impact of changes in discount rates used to measure long duration contracts | Prior to Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							0		0		0	0
Total stockholder's equity at end of period		0		0					0
Cumulative impact of changes in discount rates used to measure long duration contracts | Effect of Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							(2,365)		(4,000)		(41)	(4,000)
Total stockholder's equity at end of period		(41)		(4,000)					(2,365)
Cumulative foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period						(204)	(127)		(113)		(221)	(113)
Other comprehensive income (loss) before reclassifications						34	(68)				51	(82)
Amounts reclassified from accumulated other comprehensive income (loss) net of tax						0	0				0	0
Other comprehensive income (loss) after tax (expense) benefit						34	(68)				51	(82)
Total stockholder's equity at end of period		(221)		(113)		(170)	(195)		(127)		(170)	(195)
Income tax effects allocated directly to equity, cumulative effect of change in accounting principle		0		0					0
Reclassification from AOCI, tax						0	0				0	0
Tax (expense) benefit on other comprehensive income (loss)						$ 0	0				0	0
Cumulative foreign currency translation adjustment | Prior to Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							(127)		(113)		(221)	(113)
Total stockholder's equity at end of period		(221)		(113)					(127)
Cumulative foreign currency translation adjustment | Effect of Adoption
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Total stockholder's equity at beginning of period							$ 0		0		$ 0	$ 0
Total stockholder's equity at end of period		$ 0		$ 0					$ 0

[1] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance. See Note A to the Condensed Consolidated Financial Statements for additional information.

[2] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance. See Note A to the Condensed Consolidated Financial Statements for additional information.