Incentive Plan - Summary of Granted but Unvested Stock Award Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares, Outstanding at beginning of year	81,775	59,962	48,733
Number of Shares, Granted	70,890	40,380	28,228
Number of Shares, Vested	(23,587)	(16,438)	(14,296)
Number of Shares, Forfeited	(2,118)	(2,129)	(2,703)
Number of Shares, Outstanding at end of year	126,960	81,775	59,962
Weighted Average Grant Date Fair Value, Outstanding at beginning of year	$ 15.85	$ 13.84	$ 13.10
Weighted Average Grant Date Fair Value, Granted	17.39	17.70	14.78
Weighted Average Grant Date Fair Value, Vested	14.86	13.31	13.21
Weighted Average Grant Date Fair Value, Forfeited	15.16	14.18	13.85
Weighted Average Grant Date Fair Value, Outstanding at end of year	$ 16.90	$ 15.85	$ 13.84