Allowance for Doubtful Accounts Activity (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]      
Balance at beginning of period $ 621 $ 577 $ 793
Charged to costs and expenses 256 772 594
Write-offs, net of recoveries 294 728 810
Balance at end of period $ 583 $ 621 $ 577