Schedule II - Valuation accounts (Detail) (Allowance for Doubtful Accounts, USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Allowance for Doubtful Accounts
     
Valuation and Qualifying Accounts Disclosure [Line Items]      
Balance at Beginning of Period $ 743 $ 1,006 $ 908
Charged to Cost and Expenses (125) 263 98
Charge-off Against Allowances 0 (526) 0
Balance at End of Period $ 618 $ 743 $ 1,006