Accumulated Other Comprehensive Income - Balances in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (259)	$ (1,096)	$ (776)	[1]	$ (921)
Change in net unrealized holding gains (losses) on securities, before reclassification, net of tax expense		267	590		93
Reclassification for previously unrealized net gains recognized in income, net of tax expense (benefit)	(118)	(2)	(191)		(3)
Ending Balance	(377)	(831)	(377)		(831)
Net Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	624	(130)	107		45
Change in net unrealized holding gains (losses) on securities, before reclassification, net of tax expense		267	590		93
Reclassification for previously unrealized net gains recognized in income, net of tax expense (benefit)	(118)	(2)	(191)		(3)
Ending Balance	506	135	506		135
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