Significant Accounting Policies - Shares Used in Computation of Basic and Diluted Per Share Information (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accounting Policies [Abstract]
Document Fiscal Year Focus			2018
Weighted average shares outstanding:
Weighted average number of shares outstanding for basic per share calculation	30,497,501	17,728,567	24,178,781	17,686,134
Effect of dilutive potential shares:
Nonvested stock	244,792	235,820	224,529	225,589
Adjusted weighted average shares for diluted per share calculation	30,742,293	17,964,387	24,403,310	17,911,723
Anti-dilutive shares	20,200	0	236,037	149,100