Investments - Unrealized Losses on AFS Securities (Details) $ in Millions	Jun. 30, 2021 USD ($) security	Dec. 31, 2020 USD ($)
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 17,651	$ 7,684
Fair Value, 12 months or greater	4,086	3,834
Total	21,737	11,518
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	353	254
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	135	234
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	488	488
Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	15,089	6,336
Fair Value, 12 months or greater	3,888	3,602
Total	18,977	9,938
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	318	221
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	132	224
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 450	445
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| security	439
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security	2,597
Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 2,562	1,348
Fair Value, 12 months or greater	198	232
Total	2,760	1,580
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	35	33
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3	10
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 38	43
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| security	9
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security	45
U.S. government and agencies \| Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 243	31
Fair Value, 12 months or greater	0	0
Total	243	31
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	15	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	15	1
U.S. state, municipal and political subdivisions \| Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	55	9
Fair Value, 12 months or greater	3	6
Total	58	15
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1	0
Foreign governments \| Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	45	2
Fair Value, 12 months or greater	1	0
Total	46	2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	3	0
Corporate \| Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	10,055	2,218
Fair Value, 12 months or greater	507	248
Total	10,562	2,466
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	260	66
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	33	24
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	293	90
CLO \| Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	3,553	1,649
Fair Value, 12 months or greater	2,590	3,179
Total	6,143	4,828
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	12	33
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	57	167
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	69	200
CLO \| Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	525	336
Fair Value, 12 months or greater	184	232
Total	709	568
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3	10
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	3	13
ABS \| Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	584	1,169
Fair Value, 12 months or greater	275	84
Total	859	1,253
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	13	73
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	24	18
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	37	91
ABS \| Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	2,037	1,012
Fair Value, 12 months or greater	14	0
Total	2,051	1,012
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	35	30
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	35	30
CMBS \| Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	352	710
Fair Value, 12 months or greater	149	48
Total	501	758
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	11	37
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	13	13
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	24	50
RMBS \| Investments, excluding investments in Related Party
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	202	548
Fair Value, 12 months or greater	363	37
Total	565	585
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	11
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 8	$ 13

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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