Securities (Net Gains and Losses on Trading Account Securities) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments, Debt and Equity Securities [Abstract]
Net gain on sales transactions	$ 878	$ 1,219	$ 1,607
Net mark-to-market gains (losses)	(429)	(161)	(15)
Net gain on trading account securities	$ 449	$ 1,058	$ 1,592