Investments - Investments - Unrealized Losses on AFS Securities (Details) $ in Millions	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	4,667
Percentage of Gross Unrealized Losses Depressed Less than Twenty Percent of Cost or Amortized Cost	93.00%
ABS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,758	$ 1,577
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	24	50
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	767	281
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	49	25
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,525	1,858
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	73	75
Collateralized Loan Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	128	1,490
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	48
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,738	1,378
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	66	54
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,866	2,868
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	68	102
CMBS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	458	2,560
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	30	270
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,656	521
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	357	88
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	3,114	3,081
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	387	358
Corporate
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	4,078	11,157
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	111	1,071
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	10,121	2,575
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,293	521
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	14,199	13,732
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	1,404	1,592
Foreign Govt./Govt. Agencies
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	91	308
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	26
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	407	224
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	37	23
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	498	532
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	40	49
Municipal
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,353	4,270
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	28	461
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,864	228
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	365	54
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	4,217	4,498
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	393	515
RMBS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	690	2,311
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	31	249
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,867	1,250
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	443	259
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	3,557	3,561
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	474	508
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	412	1,554
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	29	145
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,595	633
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	187	98
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,007	2,187
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	216	243
Available-for-sale Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	8,968	25,227
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	258	2,320
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	24,015	7,090
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,797	1,122
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	32,983	32,317
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	$ 3,055	$ 3,442