Cash and Cash Equivalents (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2008
Cash, Cash Equivalents Details [Line Items]
Cash and due from banks	$ 852,010	[1]	$ 2,672,725	[1]
Securities purchased under agreements to resell	175,553	[2]	60,345	[2]
Short-term agency discount notes			330,370
Other short-term investment securities	87,385		12,992
Cash and cash equivalents	$ 1,114,948		$ 3,076,432		$ 3,512,853	$ 2,436,725

[1] At December 31, 2011 and 2010, $100.1 million and $2.2 billion, respectively, of our cash and due from banks was deposited at the Federal Reserve Bank and was earning interest at the Federal Funds target rate, and interest-earning deposits in other financial institutions were $371.5 million and $246.3 million, respectively.

[2] At December 31, 2011 and 2010, securities purchased under agreements to resell were collateralized by U.S. treasury securities and U.S. agency securities with aggregate fair values of $179.1 million and $61.6 million, respectively. None of these securities received as collateral were sold or repledged as of December 31, 2011 and 2010.