Income Taxes - Reconciliation of effective tax rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Expected income tax expense (benefit) computed on pre-tax income at weighted average income tax rate	$ 300	$ 110	$ 158
Addition (reduction) in income tax expense (benefit) resulting from:
Investment income	(14)	(13)	(24)
State taxes, net of U.S. federal tax benefit	6	11	21
Dividend withholding taxes	9	11	12
Change in valuation allowance	4	(23)	(40)
Base eroding tax	9	8	0
Share based compensation	(13)	(9)	(5)
Tax credits	(3)	(10)	0
Change in tax rate	(1,179)	(5)	0
Other	8	0	6
Income tax expense (benefit)	$ (873)	$ 80	$ 128