Reinsurance - Reinsurance Recoverables by Range of External Credit Rating and Collateral Level (Details) $ in Millions	Sep. 30, 2021 USD ($)
Ceded Credit Risk [Line Items]
Reinsurance recoverables	$ 5,279
Allowance for uncollectible reinsurance	(30)
Total reinsurance recoverables	5,249
Fair value of collateral contractually required to meet or exceed carrying value of recoverable
Ceded Credit Risk [Line Items]
Reinsurance recoverables	1,189
Collateral provisions exist that may mitigate risk of credit loss
Ceded Credit Risk [Line Items]
Reinsurance recoverables	3,805
No collateral
Ceded Credit Risk [Line Items]
Reinsurance recoverables	285
Ongoing Operations
Ceded Credit Risk [Line Items]
Reinsurance recoverables	364
Ongoing Operations | Upper-medium grade and higher
Ceded Credit Risk [Line Items]
Reinsurance recoverables	178
Ongoing Operations | Lower-medium grade
Ceded Credit Risk [Line Items]
Reinsurance recoverables	63
Ongoing Operations | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	123
Ongoing Operations | Fair value of collateral contractually required to meet or exceed carrying value of recoverable
Ceded Credit Risk [Line Items]
Reinsurance recoverables	99
Ongoing Operations | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Upper-medium grade and higher
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Ongoing Operations | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Lower-medium grade
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Ongoing Operations | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	99
Ongoing Operations | Collateral provisions exist that may mitigate risk of credit loss
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Ongoing Operations | Collateral provisions exist that may mitigate risk of credit loss | Upper-medium grade and higher
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Ongoing Operations | Collateral provisions exist that may mitigate risk of credit loss | Lower-medium grade
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Ongoing Operations | Collateral provisions exist that may mitigate risk of credit loss | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Ongoing Operations | No collateral
Ceded Credit Risk [Line Items]
Reinsurance recoverables	265
Ongoing Operations | No collateral | Upper-medium grade and higher
Ceded Credit Risk [Line Items]
Reinsurance recoverables	178
Ongoing Operations | No collateral | Lower-medium grade
Ceded Credit Risk [Line Items]
Reinsurance recoverables	63
Ongoing Operations | No collateral | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	24
Acquisition, disposition or runoff activities
Ceded Credit Risk [Line Items]
Reinsurance recoverables	4,915
Acquisition, disposition or runoff activities | Upper-medium grade and higher | Lincoln National Life and Lincoln Life & Annuity of New York
Ceded Credit Risk [Line Items]
Reinsurance recoverables	2,942
Acquisition, disposition or runoff activities | Upper-medium grade and higher | Berkshire Hathaway Life Insurance Company of Nebraska
Ceded Credit Risk [Line Items]
Reinsurance recoverables	668
Acquisition, disposition or runoff activities | Upper-medium grade and higher | Prudential Retirement Insurance and Annuity
Ceded Credit Risk [Line Items]
Reinsurance recoverables	583
Acquisition, disposition or runoff activities | Upper-medium grade and higher | Life Insurance Company of North America
Ceded Credit Risk [Line Items]
Reinsurance recoverables	451
Acquisition, disposition or runoff activities | Upper-medium grade and higher | Other
Ceded Credit Risk [Line Items]
Reinsurance recoverables	256
Acquisition, disposition or runoff activities | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	15
Acquisition, disposition or runoff activities | Fair value of collateral contractually required to meet or exceed carrying value of recoverable
Ceded Credit Risk [Line Items]
Reinsurance recoverables	1,090
Acquisition, disposition or runoff activities | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Upper-medium grade and higher | Lincoln National Life and Lincoln Life & Annuity of New York
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Acquisition, disposition or runoff activities | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Upper-medium grade and higher | Berkshire Hathaway Life Insurance Company of Nebraska
Ceded Credit Risk [Line Items]
Reinsurance recoverables	284
Acquisition, disposition or runoff activities | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Upper-medium grade and higher | Prudential Retirement Insurance and Annuity
Ceded Credit Risk [Line Items]
Reinsurance recoverables	583
Acquisition, disposition or runoff activities | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Upper-medium grade and higher | Life Insurance Company of North America
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Acquisition, disposition or runoff activities | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Upper-medium grade and higher | Other
Ceded Credit Risk [Line Items]
Reinsurance recoverables	223
Acquisition, disposition or runoff activities | Fair value of collateral contractually required to meet or exceed carrying value of recoverable | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss
Ceded Credit Risk [Line Items]
Reinsurance recoverables	3,805
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss | Upper-medium grade and higher | Lincoln National Life and Lincoln Life & Annuity of New York
Ceded Credit Risk [Line Items]
Reinsurance recoverables	2,942
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss | Upper-medium grade and higher | Berkshire Hathaway Life Insurance Company of Nebraska
Ceded Credit Risk [Line Items]
Reinsurance recoverables	384
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss | Upper-medium grade and higher | Prudential Retirement Insurance and Annuity
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss | Upper-medium grade and higher | Life Insurance Company of North America
Ceded Credit Risk [Line Items]
Reinsurance recoverables	451
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss | Upper-medium grade and higher | Other
Ceded Credit Risk [Line Items]
Reinsurance recoverables	16
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	12
Acquisition, disposition or runoff activities | No collateral
Ceded Credit Risk [Line Items]
Reinsurance recoverables	20
Acquisition, disposition or runoff activities | No collateral | Upper-medium grade and higher | Lincoln National Life and Lincoln Life & Annuity of New York
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Acquisition, disposition or runoff activities | No collateral | Upper-medium grade and higher | Berkshire Hathaway Life Insurance Company of Nebraska
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Acquisition, disposition or runoff activities | No collateral | Upper-medium grade and higher | Prudential Retirement Insurance and Annuity
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Acquisition, disposition or runoff activities | No collateral | Upper-medium grade and higher | Life Insurance Company of North America
Ceded Credit Risk [Line Items]
Reinsurance recoverables	0
Acquisition, disposition or runoff activities | No collateral | Upper-medium grade and higher | Other
Ceded Credit Risk [Line Items]
Reinsurance recoverables	17
Acquisition, disposition or runoff activities | No collateral | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	$ 3