Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details)

v3.8.0.1
Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Sep. 30, 2016
Dec. 31, 2015
Contingent Consideration | Level 3        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value $ 598 $ 541 $ 394 $ 841
Recurring        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 598 541    
Recurring | Level 1        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 0 0    
Recurring | Level 2        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 0 0    
Recurring | Level 3        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 598 541    
Recurring | Interest rate swap agreements        
Business Acquisition, Contingent Consideration [Line Items]        
Assets measured at fair value 1,073 1,098    
Recurring | Interest rate swap agreements | Level 1        
Business Acquisition, Contingent Consideration [Line Items]        
Assets measured at fair value 0 0    
Recurring | Interest rate swap agreements | Level 2        
Business Acquisition, Contingent Consideration [Line Items]        
Assets measured at fair value 1,073 1,098    
Recurring | Interest rate swap agreements | Level 3        
Business Acquisition, Contingent Consideration [Line Items]        
Assets measured at fair value 0 0    
Recurring | Contingent Consideration | AssetEye        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 255 539    
Recurring | Contingent Consideration | AssetEye | Level 1        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 0 0    
Recurring | Contingent Consideration | AssetEye | Level 2        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 0 0    
Recurring | Contingent Consideration | AssetEye | Level 3        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 255 539    
Recurring | Contingent Consideration | Indatus        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value   2    
Recurring | Contingent Consideration | Indatus | Level 1        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value   0    
Recurring | Contingent Consideration | Indatus | Level 2        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value   0    
Recurring | Contingent Consideration | Indatus | Level 3        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value   $ 2    
Recurring | Contingent Consideration | Axiometrics        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 343      
Recurring | Contingent Consideration | Axiometrics | Level 1        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 0      
Recurring | Contingent Consideration | Axiometrics | Level 2        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value 0      
Recurring | Contingent Consideration | Axiometrics | Level 3        
Business Acquisition, Contingent Consideration [Line Items]        
Liabilities measured at fair value $ 343