Consolidated Statements Of Shareholders' Equity (Parenthetical) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Net unrealized appreciation on investments, Change in period, income tax (expense) benefit	$ 353	$ (234)
Cumulative translation adjustment, Change in period, income tax(expense) benefit	27	(44)
Pension liability adjustment, Change in period, income tax (expense) benefit	(6)	2
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Unrealized appreciation on investments, Change in period before reclassification to AOCI, income tax (expense) benefit	(81)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Unrealized appreciation on investments, Change in period before reclassification to AOCI, income tax (expense) benefit	16
Income tax expense from reclassification of unrealized gains	$ (337)