Deferred Compensation Plan - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation plan liability	$ 12,700,000	$ 12,600,000
Cash surrender value of the policies	14,500,000	14,100,000
Deferred compensation expense charged to operations for Company's matching contributions	89,000	139,000	285,000
Benefits paid	$ 1,900,000	$ 1,300,000	$ 616,000
Employee
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of receipt of base compensation	75.00%
Percentage of receipt of incentive pay compensation	100.00%
Non Employee Director
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of receipt of base compensation	100.00%