Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive (Loss) Income, Net of Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning balance	$ (16,708)	$ (14,462)	$ (9,955)
Net Change	(2,746)	(2,246)	(4,507)
Ending balance	(19,454)	(16,708)	(14,462)
Net Unrealized Holding (Losses) Gains on Available-for-Sale Investment Securities [Member]
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning balance	(592)	1,711	(1,472)
Net Change	(4,396)	(2,303)	3,183
Ending balance	(4,988)	(592)	1,711
Net Change Related to Derivative Used for Cash Flow Hedge [Member]
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning balance	(285)	(157)	0
Net Change	144	(128)	(157)
Ending balance	(141)	(285)	(157)
Net Change Related to Defined Benefit Pension Plan [Member]
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning balance	(15,831)	(16,016)	(8,483)
Net Change	1,506	185	(7,533)
Ending balance	$ (14,325)	$ (15,831)	$ (16,016)