Accumulated Other Comprehensive Income - Balances in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning balance	$ (1,096)	$ (617)	$ (921)	[1]	$ (1,173)
Change in net unrealized holding gains on securities, before reclassification, net of tax expense	267	117	93		662
Reclassification for previously unrealized net gains recognized in income, net of tax expense	(2)	5	(3)		16
Ending Balance	(831)	(495)	(831)		(495)
Holding gains (losses) on securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning balance	(130)	(235)	45		(791)
Change in net unrealized holding gains on securities, before reclassification, net of tax expense	267	117	93		662
Reclassification for previously unrealized net gains recognized in income, net of tax expense	(2)	5	(3)		16
Ending Balance	135	(113)	135		(113)
Pension and Post employment costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning balance	(966)	(382)	(966)		(382)
Ending Balance	$ (966)	$ (382)	$ (966)		$ (382)

[1] Derived from the audited consolidated financial statements.