Employee Benefit Plans - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended				12 Months Ended				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013 Pension Plans, Defined Benefit [Member]	Dec. 31, 2012 Deffered Compensation Plan [Member]	Dec. 31, 2011 Deffered Compensation Plan [Member]	Dec. 31, 2010 Deffered Compensation Plan [Member]	Dec. 31, 2013 Other Pension Plans, Postretirement Or Supplemental Plans, Defined Benefit [Member]	Dec. 31, 2012 Directors and Officers [Member]	Dec. 31, 2011 Directors and Officers [Member]	Dec. 31, 2010 Directors and Officers [Member]	Dec. 31, 2012 Officer [Member]	Dec. 31, 2011 Officer [Member]	Dec. 31, 2010 Officer [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	$ 78	$ 66			$ 777	$ 717	$ 608
Annual Losses Per Individual	125
Cliams Charges To Earnings	1,799	1,620	1,489
Defined Benefit Plan, Benefit Obligation	837	734	712						2,003	2,240	2,492	298	456
Deferred Compensation Arrangement with Individual, Compensation Expense									170	183	223	0	72	135
Pension and Other Postretirement Benefit Plans, Amounts That Will Be Amortized From Accumulated Other Comprehensive Income (Loss) In Next Fiscal Year	46	2	0
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year				80				50
Defined Benefit Plan, Accumulated Benefit Obligation	$ 837	$ 734