Segment Information Segment Information - Revenue by Country of Domicile (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 232	$ 223	$ 716	$ 720
U.S.
Segment Reporting Information [Line Items]
Total revenues	186	172	579	560
Bermuda
Segment Reporting Information [Line Items]
Total revenues	33	43	105	128
U.K. and other
Segment Reporting Information [Line Items]
Total revenues	$ 13	$ 8	$ 32	$ 32