Quarterly Operating Results (Unaudited) (Details 1) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Realized gains (losses) and favorable (adverse) development on unpaid loss and loss adjustment expenses
Realized Gains (Losses) on Securities and Subsidiaries	$ (25)	$ (11)	$ (1)	$ (143)	$ 8	$ 13	$ 12	$ 19	$ (180)	$ 52
Prior Year Development Favorable (Adverse)	$ 5	$ (55)	$ 10	$ 7	$ (10)	$ (13)	$ (14)	$ 31	$ (33)	$ (6)