Employee Benefit Plan Amounts Recognized in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Schedule of Pension and Other Postretirment Benefits Recgonized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Net actuarial loss	$ 525	$ 525	$ 1,050	$ 1,050
Net prior service credit	(100)	(100)	(200)	(200)
Deferred tax (liabilities) assets	(160)	(158)	(321)	(26)
Net amount recognized	$ 265	$ 267	$ 529	$ 824