Gross Realized Gains and Losses on Sales of Securities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Gain (Loss) on Investments [Line Items]
Gross gains realized	$ 3,978	$ 4,068	$ 1,901
Gross losses realized	(852)	(1,161)	(1,487)
Net gain realized	$ 3,126	$ 2,907	$ 414