Reinsurance and Other Monoline Exposures - Effect of Reinsurance on Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Premiums Written:
Direct	$ 109	$ 21
Assumed	2	(2)
Ceded (2)	11	(17)
Net	122	2
Premiums Earned:
Direct	167	190
Assumed	6	8
Ceded	(9)	(15)
Net	164	183
Loss and LAE:
Direct	67	109
Assumed	3	(14)
Ceded	(11)	(5)
Net	$ 59	$ 90