Summary of Changes in Estimated Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value Inputs Assets Quantitative Information [Line Items]
Beginning balance	$ 683	$ 766	$ 789
Recognized gain	(24)	(83)	(23)
Ending balance		$ 683	$ 766