Reinsurance - Effect of Reinsurance on Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Premiums Written:
Direct	$ 67	$ 57	$ 156	$ 192
Assumed (1)	2	(7)	3	324
Ceded	(1)	1	12	14
Net	68	51	171	530
Premiums Earned:
Direct	113	127	317	400
Assumed	12	19	42	33
Ceded	(2)	(4)	(6)	(10)
Net	123	142	353	423
Loss and LAE:
Direct	28	18	82	53
Assumed	2	1	4	(7)
Ceded	0	(2)	(11)	(3)
Net	$ 30	$ 17	$ 75	$ 43