Reinsurance - Reinsurance Recoverables by Range of External Credit Rating and Collateral Level (Details) $ in Millions	Sep. 30, 2020 USD ($)
Ceded Credit Risk [Line Items]
Reinsurance recoverables	$ 5,331
Allowance for uncollectible reinsurance	(34)
Reinsurance recoverables classified as assets of business held for sale	(190)
Total reinsurance recoverables	5,107
Fair value of collateral contractually required to meet or exceed carrying value of recoverable
Ceded Credit Risk [Line Items]
Reinsurance recoverables	1,286
Collateral provisions exist that may mitigate risk of credit loss
Ceded Credit Risk [Line Items]
Reinsurance recoverables	3,606
No collateral
Ceded Credit Risk [Line Items]
Reinsurance recoverables	439
Ongoing Operations
Ceded Credit Risk [Line Items]
Reinsurance recoverables	530
Ongoing Operations | Upper-medium grade and higher
Ceded Credit Risk [Line Items]
Reinsurance recoverables	334
Ongoing Operations | Lower-medium grade
Ceded Credit Risk [Line Items]
Reinsurance recoverables	63
Ongoing Operations | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	133
Ongoing Operations | Fair value of collateral contractually required to meet or exceed carrying value of recoverable
Ceded Credit Risk [Line Items]
Reinsurance recoverables	90
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	90
Ongoing Operations | Collateral provisions exist that may mitigate risk of credit loss
Ceded Credit Risk [Line Items]
Reinsurance recoverables	22
Ongoing Operations | Collateral provisions exist that may mitigate risk of credit loss | Upper-medium grade and higher
Ceded Credit Risk [Line Items]
Reinsurance recoverables	8
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	14
Ongoing Operations | No collateral
Ceded Credit Risk [Line Items]
Reinsurance recoverables	418
Ongoing Operations | No collateral | Upper-medium grade and higher
Ceded Credit Risk [Line Items]
Reinsurance recoverables	326
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	29
Acquisition, disposition or runoff activities
Ceded Credit Risk [Line Items]
Reinsurance recoverables	4,801
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	3,049
Acquisition, disposition or runoff activities | Upper-medium grade and higher | Berkshire
Ceded Credit Risk [Line Items]
Reinsurance recoverables	794
Acquisition, disposition or runoff activities | Upper-medium grade and higher | Prudential Retirement Insurance and Annuity
Ceded Credit Risk [Line Items]
Reinsurance recoverables	641
Acquisition, disposition or runoff activities | Upper-medium grade and higher | Other
Ceded Credit Risk [Line Items]
Reinsurance recoverables	275
Acquisition, disposition or runoff activities | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	42
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	1,196
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
Ceded Credit Risk [Line Items]
Reinsurance recoverables	318
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	641
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	237
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	3,584
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	3,049
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss | Upper-medium grade and higher | Berkshire
Ceded Credit Risk [Line Items]
Reinsurance recoverables	476
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 | Other
Ceded Credit Risk [Line Items]
Reinsurance recoverables	21
Acquisition, disposition or runoff activities | Collateral provisions exist that may mitigate risk of credit loss | Not rated
Ceded Credit Risk [Line Items]
Reinsurance recoverables	38
Acquisition, disposition or runoff activities | No collateral
Ceded Credit Risk [Line Items]
Reinsurance recoverables	21
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
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 | 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	$ 4