Deferred Compensation Plans - Summary of Changes in Deferred Compensation Plan Liability (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation Related Costs [Abstract]
Balance, beginning of year	$ 1,087	$ 1,100	$ 990
Deferrals, dividends, and changes in fair value recorded as an expense	209	36	191
Deferred compensation payments	(70)	(49)	(81)
Balance, end of year	$ 1,226	$ 1,087	$ 1,100