Employee Benefit Plans - Summary of the Activity of the Restoration Plan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit obligation, Beginning Balance	$ 1,200
Benefit obligation, Interest cost	52	$ 45	$ 52
Benefit obligation, Actuarial loss (gain)	(108)	(122)	(102)
Defined Benefit Plan, Benefit obligation, Ending Balance	1,100	1,200
Accrued benefit liability	(1,136)	(1,239)
Net amount recognized	(1,136)	(1,239)
Net actuarial loss	538	646
Amount Recognized in OCI, Total	538	646
Change in Projected Benefit Obligation [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit obligation, Beginning Balance	1,239	1,346
Benefit obligation, Interest cost	52	45
Plan Assets, Benefits paid	(39)	(65)
Benefit obligation, Actuarial loss (gain)	103	(87)
Plan Assets, Settlement	(219)
Defined Benefit Plan, Benefit obligation, Ending Balance	1,136	1,239	1,346
Change in Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair value of plan assets, Beginning Balance	0	0
Plan Assets, Employer contributions	257	65
Plan Assets, Benefits paid	(39)	(65)
Plan Assets, Settlement	(218)
Defined Benefit Plan, Fair value of plan assets, Ending Balance	0	0	$ 0
Funded status at December 31	$ (1,136)	$ (1,239)