Consolidated Statements Of Shareholders' Equity (Parenthetical) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Statement Consolidated Statements Of Shareholders Equity [Abstract]
Change in year, before reclassification from AOCI, net of income tax benefit(expense)	$ (259)	$ (477)
Income tax benefit (expense) from reclassification of unrealized gains	3	5
Net unrealized appreciation on investments, Change in period, income tax (expense) benefit	(256)	(472)
Cumulative translation adjustment, Change in period, income tax(expense) benefit	(7)	(11)
Net income	2,398	1,165
Pension liability adjustment, Change in period, income tax (expense) benefit	$ 17	$ 1