Employee Benefit Plans - Change in Plan Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets, beginning of year	$ 2,806
Fair value of plan assets, end of year	2,690	$ 2,806
Pension Plan, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets, beginning of year	2,806	2,897
Actual return on plan assets	163	(6)
Benefits payments	(279)	(85)
Fair value of plan assets, end of year	2,690	2,806
Other Postretirement Benefit Plan, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	8	9
Benefits payments	$ (8)	$ (9)