Accumulated Other Comprehensive Income - Balances in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (445)	$ (720)	$ (776)	[1]	$ (921)
Change in net unrealized holding losses on securities, before reclassification, net of tax expense	255	(372)	590		(174)
Reclassification for previously unrealized net gains recognized in income, net of tax expense (benefit)	(69)	(4)	(73)		(1)
Ending Balance	(259)	(1,096)	(259)		(1,096)
Net Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	438	246	107		45
Change in net unrealized holding losses on securities, before reclassification, net of tax expense	255	(372)	590		(174)
Reclassification for previously unrealized net gains recognized in income, net of tax expense (benefit)	(69)	(4)	(73)		(1)
Ending Balance	624	(130)	624		(130)
Pension and Post employment costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(883)	(966)	(883)		(966)
Ending Balance	$ (883)	$ (966)	$ (883)		$ (966)

[1] Derived from Audited December 31, 2015 Financial Statements