Quarterly report pursuant to Section 13 or 15(d)

Selected Balance Sheet Data - Schedule of Other Assets (Parenthetical) (Detail)

v2.4.1.9
Selected Balance Sheet Data - Schedule of Other Assets (Parenthetical) (Detail) (USD $)
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Other Assets [Line Items]      
Allowance of doubtful accounts $ 208,000us-gaap_AllowanceForDoubtfulAccountsReceivable   $ 193,000us-gaap_AllowanceForDoubtfulAccountsReceivable
Provision for bad debt expense 21,000us-gaap_ProvisionForDoubtfulAccounts 11,000us-gaap_ProvisionForDoubtfulAccounts  
Write-off receivables $ 6,000us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs $ 41,000us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs  
Minimum [Member]      
Other Assets [Line Items]      
Notes receivable due period 1 year    
Maximum [Member]      
Other Assets [Line Items]      
Notes receivable due period 5 years