Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits [Line Items]
Unrecognized tax benefits beginning balance	$ 806	$ 656	$ 635
Gross increases for tax positions of prior years	222	257	229
Gross decreases for tax positions of prior years	(409)
Settlements	(325)	(107)	(208)
Unrecognized tax benefits ending balance	$ 294	$ 806	$ 656