Accounting Changes and Error Corrections (Income Statement) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net premiums	$ 4,255.0	$ 3,247.0	$ 10,977.0	$ 9,632.0
Net investment income	922.0	769.0	2,635.0	2,333.0
Total investment related gains (losses), net	(126.0)	(154.0)	(326.0)	(533.0)
Other revenues	102.0	188.0	274.0	438.0
Revenues	5,153.0	4,050.0	13,560.0	11,870.0
Claims and other policy benefits	3,959.0	3,048.0	10,035.0	8,857.0
Liability for Future Policy Benefit, Remeasurement Gain (Loss)	(82.0)	226.0	(95.0)	302.0
Market Risk Benefit, Change in Fair Value, Gain (Loss)	(21.0)	23.0	(38.0)	29.0
Interest credited	223.0	189.0	647.0	468.0
Policy acquisition costs and other insurance expenses	348.0	341.0	1,028.0	1,021.0
Other operating expenses	274.0	251.0	799.0	720.0
Interest expense	72.0	49.0	188.0	136.0
Benefits, Losses and Expenses	4,773.0	4,127.0	12,564.0	11,533.0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	380.0	(77.0)	996.0	337.0
Provision for income taxes	91.0	(2.0)	247.0	109.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	289.0	(75.0)	749.0	228.0	$ 521.0
Net Income (Loss) Attributable to Noncontrolling Interest	2.0	1.0	5.0	2.0	4.0
Net income	$ 287.0	$ (76.0)	$ 744.0	$ 226.0	517.0	$ 1,170.0
Accounting Standards Update 2018-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net premiums					13,078.0	12,513.0
Net investment income					3,161.0	3,138.0
Total investment related gains (losses), net					(539.0)	567.0
Other revenues					527.0	449.0
Revenues					16,227.0	16,667.0
Claims and other policy benefits					11,982.0	11,673.0
Liability for Future Policy Benefit, Remeasurement Gain (Loss)					291.0	567.0
Market Risk Benefit, Change in Fair Value, Gain (Loss)					10.0	(58.0)
Interest credited					682.0	700.0
Policy acquisition costs and other insurance expenses					1,344.0	1,325.0
Other operating expenses					1,009.0	936.0
Interest expense					184.0	127.0
Collateral finance and securitization expense					7.0	12.0
Benefits, Losses and Expenses					15,509.0	15,282.0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest					718.0	1,385.0
Provision for income taxes					197.0	215.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest					521.0	1,170.0
Net Income (Loss) Attributable to Noncontrolling Interest					4.0	0.0
Net income					517.0	1,170.0
Accounting Standards Update 2018-12 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net premiums					13,078.0	12,513.0
Net investment income					3,161.0	3,138.0
Total investment related gains (losses), net					(506.0)	560.0
Other revenues					525.0	447.0
Revenues					16,258.0	16,658.0
Claims and other policy benefits					12,046.0	12,776.0
Liability for Future Policy Benefit, Remeasurement Gain (Loss)					0.0	0.0
Market Risk Benefit, Change in Fair Value, Gain (Loss)					0.0	0.0
Interest credited					682.0	700.0
Policy acquisition costs and other insurance expenses					1,499.0	1,416.0
Other operating expenses					1,009.0	936.0
Interest expense					184.0	127.0
Collateral finance and securitization expense					7.0	12.0
Benefits, Losses and Expenses					15,427.0	15,967.0
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest					831.0	691.0
Provision for income taxes					204.0	74.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest					627.0	617.0
Net Income (Loss) Attributable to Noncontrolling Interest					4.0	0.0
Net income					623.0	617.0
Accounting Standards Update 2018-12 | Revision of Prior Period, Change in Accounting Principle, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net premiums					0.0	0.0
Net investment income					0.0	0.0
Total investment related gains (losses), net					(33.0)	7.0
Other revenues					2.0	2.0
Revenues					(31.0)	9.0
Claims and other policy benefits					(64.0)	(1,103.0)
Liability for Future Policy Benefit, Remeasurement Gain (Loss)					291.0	567.0
Market Risk Benefit, Change in Fair Value, Gain (Loss)					10.0	(58.0)
Interest credited					0.0	0.0
Policy acquisition costs and other insurance expenses					(155.0)	(91.0)
Other operating expenses					0.0	0.0
Interest expense					0.0	0.0
Collateral finance and securitization expense					0.0	0.0
Benefits, Losses and Expenses					82.0	(685.0)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest					(113.0)	694.0
Provision for income taxes					(7.0)	141.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest					(106.0)	553.0
Net Income (Loss) Attributable to Noncontrolling Interest					0.0	0.0
Net income					$ (106.0)	$ 553.0