Valuation and Qualifying Accounts - Valuation and Qualifying Accounts (Detail) (Allowance for Doubtful Accounts [Member], USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Allowance for Doubtful Accounts [Member]
     
Valuation and Qualifying Accounts Disclosure [Line Items]      
Balance, beginning of year $ 373 $ 339 $ 97
Additions charged to operations   34 242
Deletions from Reserve 278    
Balance, end of year $ 95 $ 373 $ 339