Property and Equipment - Additional Information (Detail) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Property, Plant and Equipment [Line Items]      
Capitalized costs of internally developed software $ 0 $ 0 $ 0
Depreciation and amortization expense $ 3,400,000 $ 3,400,000 $ 3,200,000