Reinsurance - Effect of Reinsurance on Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Premiums Written:
Direct	$ 97	$ 122	$ 256	$ 334
Assumed	9	(1)	21	0
Ceded	0	1	0	3
Net	106	122	277	337
Premiums Earned:
Direct	97	100	287	307
Assumed	6	8	22	28
Ceded	(1)	(1)	(2)	(4)
Net	102	107	307	331
Loss and LAE:
Direct	(70)	72	(37)	118
Assumed	4	4	2	15
Ceded	(2)	(3)	(19)	(3)
Net	$ (68)	$ 73	$ (54)	$ 130