Accumulated Other Comprehensive Income - Balances in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning balance	$ (720)	$ (850)	$ (921)	[1]	$ (1,173)
Change in net unrealized holding gains on securities, before reclassification, net of tax expense	(372)	223	(174)		545
Reclassification for previously unrealized net gains recognized in income, net of tax expense	(4)	10	(1)		11
Ending Balance	(1,096)	(617)	(1,096)		(617)
Holding gains (losses) on securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning balance	246	(468)	45		(791)
Change in net unrealized holding gains on securities, before reclassification, net of tax expense	(372)	223	(174)		545
Reclassification for previously unrealized net gains recognized in income, net of tax expense	(4)	10	(1)		11
Ending Balance	(130)	(235)	(130)		(235)
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.