Stock Options and Restricted Stock - Stock Options Outstanding (Detail) - 2005 Incentive Plan [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding, Beginning balance	20,000	88,879	282,083
Shares, Granted	0	0	0
Shares, Exercised	0	(68,879)	(193,204)
Shares Canceled, forfeited, or expired	0	0	0
Shares outstanding, Ending balance	20,000	20,000	88,879	282,083
Shares exercisable, Ending balance	20,000	20,000	88,879
Weighted- Average Exercise Price, Beginning balance	$ 8.71	$ 12.10	$ 11.30
Weighted- Average Exercise Price, Granted	0	0	0
Weighted- Average Exercise Price, Exercised	0	12.14	9.55
Weighted- Average Exercise Price, Canceled, forfeited, or expired	0	0	0
Weighted- Average Exercise Price, Ending balance	5.21	8.71	12.10	$ 11.30
Weighted- Average Exercise Price, Exercisable Ending balance	$ 5.21	$ 8.71	$ 12.10
Weighted- Average Remaining Contractual Life (in years)	2 years 1 month 6 days	3 years 1 month 6 days	4 years 3 months 18 days	3 years 7 months 6 days
Weighted- Average Remaining Contractual Life (in years), Exercised		3 years 3 months 18 days
Weighted- Average Remaining Contractual Life (in years), Exercisable	2 years 1 month 6 days	3 years 1 month 6 days	4 years 3 months 18 days