Investments (Schedule Of Components Of Restricted Assets) (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Trust funds	$ 11,862	$ 10,838
Deposits with non-U.S. regulatory authorities	2,075	2,305
Assets pledged under reverse repurchase agreements	1,459	1,431
Deposits with U.S. regulatory authorities	1,242	1,345
Other pledged assets	392	457
Total restricted assets	$ 17,030	$ 16,376