Reinsurance - Effect of Reinsurance on Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Premiums Written:
Direct	$ 148	$ 50	$ 212	$ 89
Assumed	1	1	1	1
Ceded	2	(2)	2	13
Net	151	49	215	103
Premiums Earned:
Direct	113	99	207	204
Assumed	10	15	20	30
Ceded	(2)	(2)	(3)	(4)
Net	121	112	224	230
Loss and LAE:
Direct	38	0	46	54
Assumed	(1)	1	11	2
Ceded	0	(2)	0	(11)
Net	$ 37	$ (1)	$ 57	$ 45