Segment Information - Supplemental Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net earned premiums	$ 344	$ 494	$ 414
Net investment income	365	269	269
Loss and LAE (benefit)	162	16	(220)
Amortization of DAC	13	14	14
Other Expenses	468	425	409
Operating Segments
Segment Reporting Information [Line Items]
Net earned premiums	347	497	418
Net investment income	370	278	280
Loss and LAE (benefit)	161	12	(221)
Amortization of DAC	13	14	14
Other Expenses	338	350	347
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Net earned premiums	347	497	418
Net investment income	370	278	280
Loss and LAE (benefit)	161	12	(221)
Amortization of DAC	13	14	14
Other Expenses	261	232	240
Non-cash compensation and operating expenses	38	41	56
Operating Segments | Asset Management
Segment Reporting Information [Line Items]
Net earned premiums	0	0	0
Net investment income	0	0	0
Loss and LAE (benefit)	0	0	0
Amortization of DAC	0	0	0
Other Expenses	77	118	107
Non-cash compensation and operating expenses	8	18	17
Corporate division
Segment Reporting Information [Line Items]
Net earned premiums	0	0	0
Net investment income	8	4	2
Loss and LAE (benefit)	0	0	0
Amortization of DAC	0	0	0
Other Expenses	117	54	41
Non-cash compensation and operating expenses	18	13	5
Other Operating Segments And Intersegment Eliminations
Segment Reporting Information [Line Items]
Net earned premiums	(3)	(3)	(4)
Net investment income	(13)	(13)	(13)
Loss and LAE (benefit)	3	8	15
Amortization of DAC	0	0	0
Other Expenses	13	21	21
Subtotal
Segment Reporting Information [Line Items]
Net earned premiums	344	494	414
Net investment income	365	269	269
Loss and LAE (benefit)	164	20	(206)
Amortization of DAC	13	14	14
Other Expenses	468	425	409
Segment Reconciling Items
Segment Reporting Information [Line Items]
Net earned premiums	0	0	0
Net investment income	0	0	0
Loss and LAE (benefit)	(2)	(4)	(14)
Amortization of DAC	0	0	0
Other Expenses	$ 0	$ 0	$ 0