Summary of Activity Related to Uncertain Tax Positions (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Contingency [Line Items]
Balance at January 1	$ 1,315	$ 1,342	$ 3,110
Additions based on tax positions related to the current year	178	149	172
Additions for tax positions of prior years	22	18	523
Prior year reductions	(13)	(26)	(46)
Statute expirations	(90)	(63)	(2,231)
Settlements		(105)	(186)
Balance at December 31	$ 1,412	$ 1,315	$ 1,342