Accumulated Other Comprehensive Income - Balances in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014 Holding gains (losses) on securities	Jun. 30, 2013 Holding gains (losses) on securities	Jun. 30, 2014 Holding gains (losses) on securities	Jun. 30, 2013 Holding gains (losses) on securities	Jun. 30, 2014 Pension and Post employment costs	Mar. 31, 2014 Pension and Post employment costs	Dec. 31, 2013 Pension and Post employment costs	Jun. 30, 2013 Pension and Post employment costs	Mar. 31, 2013 Pension and Post employment costs	Dec. 31, 2012 Pension and Post employment costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning balance	$ (850)	$ (431)	$ (1,173)	[1]	$ (381)	$ (468)	$ 229	$ (791)	$ 279	$ (382)	$ (382)	$ (382)	$ (660)	$ (660)	$ (660)
Change in net unrealized holding gains (losses) on securities, before reclassification, net of tax expense (benefit)	223	(820)	545		(868)	223	(820)	545	(868)
Reclassification for previously unrealized net (gains) losses recognized in income, net of tax (expense) benefit	10	(98)	11		(100)	10	(98)	11	(100)
Ending Balance	$ (617)	$ (1,349)	$ (617)		$ (1,349)	$ (235)	$ (689)	$ (235)	$ (689)	$ (382)	$ (382)	$ (382)	$ (660)	$ (660)	$ (660)

[1] Derived from the audited consolidated financial statements.