Employee Benefit Plans - Components of Net Periodic Benefit Cost (Gain) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Pension Plan, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	$ 134	$ 131
Expected (return) on plan assets	(189)	(196)
Amortization of prior service cost	0	0
Amortization of net obligation at transition	0	0
Recognized net loss due to settlement	90
Recognized net actuarial loss	77	76
Net periodic benefit (gain) cost	112	11
Other Postretirement Benefit Plan, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	22	23
Interest cost	28	30
Amortization of prior service cost	0	0
Amortization of net obligation at transition	0	0
Net periodic benefit (gain) cost	$ 50	$ 53