Investments - Investments - Unrealized Losses on AFS Securities (Details) $ in Millions	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	4,565
Percentage of Gross Unrealized Losses Depressed Less than Twenty Percent of Cost or Amortized Cost	94.00%
ABS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,225	$ 1,577
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	17	50
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	562	281
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	40	25
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,787	1,858
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	57	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	403	1,490
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	6	48
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,551	1,378
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	73	54
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,954	2,868
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	79	102
CMBS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	914	2,560
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	52	270
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,232	521
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	289	88
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	3,146	3,081
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	341	358
Corporate
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	6,114	11,157
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	278	1,071
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	7,233	2,575
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	999	521
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	13,347	13,732
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	1,277	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	133	308
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	6	26
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	363	224
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	34	23
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	496	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	2,125	4,270
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	92	461
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,832	228
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	278	54
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	3,957	4,498
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	370	515
RMBS
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,008	2,311
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	59	249
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,488	1,250
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	378	259
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	3,496	3,561
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	437	508
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	857	1,554
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	54	145
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,102	633
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	126	98
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,959	2,187
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	180	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	12,779	25,227
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	564	2,320
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	18,363	7,090
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,217	1,122
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	31,142	32,317
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	$ 2,781	$ 3,442

Percentage of gross unrealized losses depressed less than twenty percent of cost or amortized cost.

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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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Amount of accumulated unrealized loss on 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 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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