Schedule of Changes in Unrecognized Tax Benefit (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Unrecognized Tax Benefits [Line Items]
Beginning Balance	$ 2,194	$ 1,343
Additions based on tax positions related to the current year	214	536
Additions for tax positions for prior years	68	482
Reductions for tax positions of prior years	(820)	(167)
Ending Balance	$ 1,656	$ 2,194