Investments (Repurchase Agreements and Securities Lending Transactions) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	$ 8,223	$ 10,185
Total cash collateral for loaned securities	5,865	4,251
Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	7,723	9,747
Total cash collateral for loaned securities	5,865	4,251
Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	250	0
Total cash collateral for loaned securities	0	0
30 days or greater
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	250	438
Total cash collateral for loaned securities	0	0
U.S. Treasury securities and obligations of U.S. government authorities and agencies
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	7,542	9,482
Total cash collateral for loaned securities	1	1
U.S. Treasury securities and obligations of U.S. government authorities and agencies | Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	7,042	9,044
Total cash collateral for loaned securities	1	1
U.S. Treasury securities and obligations of U.S. government authorities and agencies | Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	250	0
Total cash collateral for loaned securities	0	0
U.S. Treasury securities and obligations of U.S. government authorities and agencies | 30 days or greater
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	250	438
Obligations of U.S. states and their political subdivisions
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	54	84
Obligations of U.S. states and their political subdivisions | Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	54	84
Obligations of U.S. states and their political subdivisions | Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	0	0
Foreign government bonds
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	365	205
Foreign government bonds | Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	365	205
Foreign government bonds | Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	0	0
U.S. public corporate securities
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	4,000	2,834
U.S. public corporate securities | Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	4,000	2,834
U.S. public corporate securities | Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	0	0
Foreign public corporate securities
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	805	643
Foreign public corporate securities | Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	805	643
Foreign public corporate securities | Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	0	0
Commercial mortgage-backed securities
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	576	486
Commercial mortgage-backed securities | Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	576	486
Commercial mortgage-backed securities | Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	0	0
Commercial mortgage-backed securities | 30 days or greater
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	0	0
Residential mortgage-backed securities
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	105	217
Residential mortgage-backed securities | Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	105	217
Residential mortgage-backed securities | Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	0	0
Residential mortgage-backed securities | 30 days or greater
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total securities sold under agreements to repurchase	0	0
Equity securities
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	640	484
Equity securities | Overnight & Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	640	484
Equity securities | Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Total cash collateral for loaned securities	$ 0	$ 0