Investments (Schedule Of Components Of Restricted Assets) (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Trust funds	$ 11,681	$ 11,862
Deposits with non-U.S. regulatory authorities	2,260	2,075
Assets pledged under repurchase agreements	1,473	1,459
Deposits with U.S. regulatory authorities	2,523	1,242
Other pledged assets	400	392
Total restricted assets	$ 18,337	$ 17,030