Summary of Stock Options Activity and Related Information (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Options
Beginning balance	20,000	50,000	141,077
Granted	0	0	0
Canceled	0	0	0
Exercised	0	0	(75,000)
Expired/Forfeited	0	(30,000)	(16,077)
Ending balance	20,000	20,000	50,000
Granted	0	0	0
Canceled	0	0	0
Exercisable at December 31, 2017	20,000
Weighted Average Exercise Price
Beginning balance	$ 12.29	$ 17.18	$ 11.87
Granted	0	0	0
Canceled	0	0	0
Exercised	0	0	9.84
Expired/Forfeited	0	20.44	4.82
Ending balance	12.29	$ 12.29	$ 17.18
Exercisable at December 31, 2017	$ 12.29