Consolidated Statements Of Shareholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Comprehensive Income (Loss), Available-for-sale Securities, before Reclassification Adjustments, Tax	$ 72	$ 154	$ (176)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	28	(2)	9
Net unrealized appreciation on investments, Change in year, income tax (expense) benefit	100	152	(167)
Cumulative translation adjustment, Change in year, income tax(expense) benefit	30	0	(12)
Pension liability adjustment, Change in year, income tax (expense) benefit	$ (184)	$ (6)	$ 4