Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Statement of Cash Flows [Abstract]
Net cash flows provided by (used in) operating activities			$ 436	$ (1,794)
Fixed-maturity securities, available-for-sale:
Purchases			(290)	(180)
Sales	$ 239	$ 296	694	353
Maturities and paydowns			298	389
Short-term investments with original maturities of over three months:
Purchases			(13)	(28)
Sales			4	0
Maturities and paydowns			15	9
Net sales (purchases) of short-term investments with original maturities of less than three months			(845)	379
Sales of fixed-maturity securities, trading			0	68
Paydowns of financial guaranty variable interest entities’ assets			14	44
Purchases of other invested assets			(15)	(8)
Sales and return of capital of other invested assets			11	34
Other			(1)	(2)
Net cash flows provided by (used in) investing activities			(128)	1,058
Cash flows from financing activities:
Dividends paid			(35)	(33)
Repurchases of common shares			(26)	(303)
Net paydowns of financial guaranty variable interest entities’ liabilities			(14)	(65)
Other			(15)	(7)
Cash flows from consolidated investment vehicles:
Proceeds from issuance of collateralized loan obligations			0	1,372
Repayment of collateralized loan obligations			(1)	(372)
Proceeds from issuance of warehouse financing debt			0	791
Repayment of warehouse financing debt			(166)	(744)
Borrowing (payment) under credit facilities			(4)	1
Contributions from noncontrolling interests to consolidated investment vehicles			0	35
Distributions to noncontrolling interests from consolidated investment vehicles			(72)	(16)
Net cash flows provided by (used in) financing activities			(333)	659
Effect of foreign exchange rate changes			2	(2)
Increase (decrease) in cash and cash equivalents and restricted cash			(23)	(79)
Cash and cash equivalents and restricted cash at beginning of period			207	342	$ 342
Cash and cash equivalents and restricted cash at end of period	184	263	184	263	207
Supplemental cash flow information
Income taxes paid (received)			2	97
Interest paid on long-term debt			41	38
Supplemental disclosure of non-cash activities:
Fixed-maturity securities, available-for-sale, received as salvage			1	610
Fixed-maturity securities, available-for-sale, ceded to a reinsurer			0	27
Fixed-maturity securities, trading, received as salvage			0	183
Fixed-maturity securities, trading, ceded to a reinsurer			0	6
Debt securities of financial guaranty variable interest entities received as salvage			0	54
Contributions from noncontrolling interests			20	26
Distributions to noncontrolling interests			20	20
Reconciliation of cash and cash equivalents and restricted cash to the condensed consolidated balance sheets:
Cash	114	138	114	138	107
Restricted cash (included in other assets)	1	0	1	0
Cash and cash equivalents of consolidated investment vehicles (See Note 8)	49	125	49	125
Cash	20	0	20	0
Cash and cash equivalents and restricted cash at end of period	$ 184	$ 263	$ 184	$ 263	$ 207