Segment Information Segment Information - Revenue by Country of Domicile (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 294	$ 263	$ 484	$ 497
United States [Member]
Segment Reporting Information [Line Items]
Total revenues	243	212	393	394
Bermuda [Member]
Segment Reporting Information [Line Items]
Total revenues	38	46	72	90
United Kingdom and Other [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 13	$ 5	$ 19	$ 13