Reinsurance - Effect of Reinsurance on Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Premiums Written:
Direct	$ 122	$ 67	$ 334	$ 156
Assumed	(1)	2	0	3
Ceded	1	(1)	3	12
Net	122	68	337	171
Premiums Earned:
Direct	100	113	307	317
Assumed	8	12	28	42
Ceded	(1)	(2)	(4)	(6)
Net	107	123	331	353
Loss and LAE:
Direct	72	28	118	82
Assumed	4	2	15	4
Ceded	(3)	0	(3)	(11)
Net	$ 73	$ 30	$ 130	$ 75