Income Taxes - Effective Tax Rate Reconciliation and Pretax Income (Loss) and Revenue by Tax Jurisdiction (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pre-tax Income Taxes and Revenue [Line Items]
Expected tax provision (benefit)	$ 23	$ 20
Tax-exempt interest	(2)	(3)
NCI	(1)	(3)
State taxes	2	3
Foreign taxes	5	5
Global minimum tax	5	0
Stock based compensation	0	1
Other	(1)	0
Total provision (benefit) for income taxes	$ 31	$ 23
Effective tax rate	21.40%	19.10%
Pretax income (loss)	$ 144	$ 120
Revenues	245	283
United States
Pre-tax Income Taxes and Revenue [Line Items]
Pretax income (loss)	129	108
Revenues	204	235
Bermuda
Pre-tax Income Taxes and Revenue [Line Items]
Pretax income (loss)	30	25
Revenues	36	35
U.K.
Pre-tax Income Taxes and Revenue [Line Items]
Pretax income (loss)	(11)	(11)
Revenues	6	13
France
Pre-tax Income Taxes and Revenue [Line Items]
Pretax income (loss)	(4)	(2)
Revenues	$ (1)	$ 0