Changes in Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Schedule of Unrecognized Tax Benefits [Line Items]
Balance, beginning of year	$ 614	$ 539
Additions based on tax positions related to the current year	52	50
Additions for tax positions of prior years	1	49
Reductions for tax positions of prior years
Reductions due to statute expiration	(155)	(24)
Settlements	(4)
Balance, end of year	$ 508	$ 614