Income Taxes - Reconciliation of Beginning and Ending Amount of Uncertain Tax Positions (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Uncertain Tax Position Reconciliation [Line Items]
Balance at beginning of year	$ 709	$ 700	$ 608
Additions based on tax positions related to the current year	131	217	131
Additions based on tax positions of prior years	1,937
Reductions for tax positions of prior years	(485)	(51)	(35)
Settlements		(157)	(4)
Balance at end of year	$ 2,292	$ 709	$ 700