Retirement Plans - Schedule of Changes in Benefit Obligations and Plan Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	$ 0	$ 0	$ 0
Interest cost	67	62	62
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Funded Status at End of Year	1,394	1,815
Unrecognized transition obligation	0	0
Unrecognized net gain	345	15
Amounts recognized in retained earnings	1,739	1,830
Change in Benefit Obligation [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	1,815	1,822
Service cost	0	0
Interest cost	67	62
Amendments	0	0
Actuarial gain	(337)	98
Net benefits paid	(151)	(167)
Benefit obligation at end of year	1,394	1,815	1,822
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Net benefits paid	(151)	(167)
Change In Plan Assets [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Net benefits paid	(151)	(167)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	151	167
Net benefits paid	(151)	(167)
Fair value of plan assets at end of year	$ 0	$ 0	$ 0