Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Statement of Cash Flows [Abstract]
Net cash flows provided by (used in) operating activities				$ 1	$ 258
Fixed-maturity securities, available-for-sale:
Purchases				(968)	(458)
Sales	$ 87		$ 73	575	767
Maturities and paydowns				577	528
Short-term investments with original maturities of over three months:
Purchases				(1)	(16)
Sales				0	4
Maturities and paydowns				5	35
Net sales (purchases) of short-term investments with original maturities of less than three months				172	(638)
Sales of fixed-maturity securities, trading				233	0
Maturities and paydowns of fixed-maturity securities, trading				5	0
Paydowns of financial guaranty variable interest entities’ assets				18	88
Purchases of and contributions to other invested assets				(103)	(128)
Sales of and return of capital from other invested assets				35	16
Sale of asset management subsidiaries, net of cash				0	(14)
Other				(4)	(1)
Net cash flows provided by (used in) investing activities				544	183
Cash flows from financing activities:
Dividends paid				(52)	(51)
Repurchases of common shares				(412)	(90)
Net paydowns of financial guaranty variable interest entities’ liabilities				(157)	(141)
Issuance of long-term debt, net of issuance costs				0	345
Redemption of debt				0	(330)
Payments related to tax withholding for share-based compensation				(30)	(16)
Other				2	1
Cash flows from consolidated investment vehicles:
Repayment of collateralized loan obligations				0	(1)
Repayment of warehouse financing debt				0	(166)
Borrowing (payment) under credit facilities				0	(4)
Distributions to noncontrolling interests from consolidated investment vehicles				(10)	(80)
Net cash flows provided by (used in) financing activities				(659)	(533)
Effect of foreign exchange rate changes				2	0
Increase (decrease) in cash and cash equivalents and restricted cash				(112)	(92)
Cash and cash equivalents and restricted cash at beginning of period		$ 115		286	207	$ 207
Cash and cash equivalents and restricted cash at end of period	174	286	115	174	115	286
Supplemental cash flow information
Income taxes paid (received)				59	3
Interest paid on long-term debt				66	55
Supplemental disclosure of non-cash activities:
Fixed-maturity securities, available-for-sale, received as salvage				0	1
Contributions from noncontrolling interests				0	20
Distributions to noncontrolling interests				0	27
Assets acquired				0	444
Assets transferred				0	241
Liabilities transferred				0	66
Reconciliation of cash and cash equivalents and restricted cash to the condensed consolidated balance sheets:
Cash	147	97	108	147	108	97
Restricted cash (included in other assets)	4		0	4	0
Cash and cash equivalents of consolidated investment vehicles (See Note 8)	23		7	23	7
Cash and cash equivalents and restricted cash at end of period	$ 174	$ 286	$ 115	$ 174	$ 115	$ 286