Geographic Regions (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Revenues and Pretax Income (Loss) by Geographic Location [Line Items]
Revenues	$ 139	$ 76	$ 349	$ 266	$ 377	$ 388	$ 418	$ 432	$ 830	$ 1,615	$ 1,461
Pretax income	$ 120	$ 46	$ 114	$ 42	$ 132	$ 131	$ 130	$ 119	322	512	416
United States [Member]
Segment Revenues and Pretax Income (Loss) by Geographic Location [Line Items]
Revenues									533	1,133	1,033
Pretax income									142	61	28
Outside the United States [Member]
Segment Revenues and Pretax Income (Loss) by Geographic Location [Line Items]
Revenues									297	482	428
Pretax income									$ 180	$ 451	$ 388