Summary of Cash and Cash Equivalents (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Due from the Federal Reserve	$ 684,947		$ 1,608,279
Cash and due from banks	593,956	521,001	319,535
Cash and cash equivalents at end of period	$ 1,278,903	$ 2,582,428	$ 1,927,814	$ 1,366,394