Income Taxes - Effective Tax Rate Reconciliation and Pretax Income (Loss) and Revenue by Tax Jurisdiction (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pre-tax Income Taxes and Revenue [Line Items]
Expected tax provision (benefit)	$ (2)	$ 23	$ 12	$ 22
Tax-exempt interest	(4)	(4)	(7)	(8)
Noncontrolling interest	(5)	(1)	(6)	(2)
State taxes	4	4	8	7
Foreign taxes	9	0	10	2
Stock based compensation	2	0	4	0
Other	(1)	1	0	2
Total provision (benefit) for income taxes	$ 3	$ 23	$ 21	$ 23
Effective tax rate	(12.90%)	18.50%	30.30%	16.50%
Pretax income (loss)	$ (22)	$ 125	$ 71	$ 140
Revenues	90	196	390	373
United States
Pre-tax Income Taxes and Revenue [Line Items]
Pretax income (loss)	25	106	109	102
Revenues	106	150	375	284
Bermuda
Pre-tax Income Taxes and Revenue [Line Items]
Pretax income (loss)	(10)	16	17	36
Revenues	6	28	39	58
U.K.
Pre-tax Income Taxes and Revenue [Line Items]
Pretax income (loss)	(31)	3	(45)	4
Revenues	(18)	17	(18)	30
Other
Pre-tax Income Taxes and Revenue [Line Items]
Pretax income (loss)	(6)	0	(10)	(2)
Revenues	$ (4)	$ 1	$ (6)	$ 1