Employee Benefit Plans (Detail) - Changes in Plan Assets and Benefit Obligations in Other Comprehensive Income (loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Retirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial (loss) gain	$ (92)	$ 298
Settlement losses	50	52
Plan amendment and curtailment	0	0
Recognized net actuarial gain	20	66
Amortization of prior service cost	0	0
Recognition of prior service cost due to curtailments	0	0
Total other comprehensive income (loss), pre-tax	(22)	416
Income tax provision (benefit)	(155)	166
Total other comprehensive income (loss), net of tax	133	250
Post Retirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial (loss) gain	(1,632)	558
Settlement losses	0	0
Plan amendment and curtailment	1,183	0
Recognized net actuarial gain	18	28
Amortization of prior service cost	369	647
Recognition of prior service cost due to curtailments	(52)	0
Total other comprehensive income (loss), pre-tax	(852)	(61)
Income tax provision (benefit)	(6)	(22)
Total other comprehensive income (loss), net of tax	$ (846)	$ (39)