Cash and Cash Equivalents (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012	Dec. 31, 2011
Cash and Cash Equivalents [Abstract]
Cash and due from banks	$ 1,144,926	[1]	$ 752,056	[1]
Securities purchased under agreements to resell	338,687	[2]	133,357	[2]
Other short-term investment securities	35,636		123,570
Total cash and cash equivalents	$ 1,519,249		$ 1,008,983		$ 850,624	$ 1,114,948

[1] At March 31, 2013 and December 31, 2012, $634 million and $72 million, respectively, of our cash and due from banks was deposited at the FRB and was earning interest at the Federal Funds target rate, and interest-earning deposits in other financial institutions were $213 million and $283 million, respectively.

[2] At March 31, 2013 and December 31, 2012, securities purchased under agreements to resell were collateralized by U.S. treasury securities and U.S. agency securities with aggregate fair values of $345 million and $136 million, respectively. None of these securities received as collateral were sold or repledged as of March 31, 2013 or December 31, 2012.