Significant Accounting Policies - Shares Used in Computation of Basic and Diluted Per Share Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Weighted average shares outstanding:
Weighted average number of shares outstanding for basic per share calculation	17,740,818	17,588,163	17,704,561	17,546,773
Effect of dilutive potential shares:
Options	0	0	0	1,146
Nonvested stock	269,704	131,310	227,139	116,365
Adjusted weighted average shares for diluted per share calculation	18,010,522	17,719,473	17,931,700	17,664,284
Anti-dilutive shares	0	20,001	137,400	214,856