Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive (Loss) Income, Net of Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning balance	$ (14,462)	$ (9,955)	$ (6,920)
Net Change	(2,246)	(4,507)	(3,035)
Ending balance	(16,708)	(14,462)	(9,955)
Net Unrealized Holding (Losses) Gains on Available-for-Sale Investment Securities [Member]
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning balance	1,711	(1,472)	8,344
Net Change	(2,303)	3,183	(9,816)
Ending balance	(592)	1,711	(1,472)
Net Change Related to Derivative Used for Cash Flow Hedge [Member]
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning balance	(157)	0	(1,241)
Net Change	(128)	(157)	1,241
Ending balance	(285)	(157)	0
Net Change Related to Defined Benefit Pension Plan [Member]
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning balance	(16,016)	(8,483)	(14,023)
Net Change	185	(7,533)	5,540
Ending balance	$ (15,831)	$ (16,016)	$ (8,483)