Claim and Claim Adjustment Expense Reserves - Impact of Loss Portfolio Transfer on the Consolidated Statement of Operations (Details) - Loss Portfolio Transfer - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Net A&EP adverse development before consideration of LPT	$ 0	$ 0	$ 60	$ 200
Retroactive reinsurance benefit recognized	(3)	(9)	(43)	(82)
Pretax impact of A&EP reserve development and the LPT	$ (3)	$ (9)	$ 17	$ 118