XML 54 R41.htm IDEA: XBRL DOCUMENT v3.10.0.1
Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
 9 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Accounting Policies [Line Items]          
Accounts receivable, net   $ 314,900,000 $ 258,300,000 $ 226,800,000  
Research and development expense   63,264,000 47,324,000 43,154,000  
Impairments of intangible assets   0 0 0  
Impairments of long-lived assets   0 0 0  
Purchase of held to maturity securities   $ 97,700,000      
Grade corporate and municipal bonds, maturity date   2018 through 2022      
Cost-method investment impairment   $ 0 0 0  
Cash and cash equivalents   134,279,000 $ 185,926,000 $ 36,151,000 $ 33,087,000
Convertible Preferred Stock | Record Holdings Pty Limited          
Accounting Policies [Line Items]          
Cost method investment   $ 15,000,000      
Investment percentage   20.00%      
Minimum          
Accounting Policies [Line Items]          
Typical contract term (in years) 3 years 3 years      
Contract term (in years)   1 year      
Revenue from contract with customer, percentage withheld from progress billing 5.00%        
Accounts receivable, payment term (in days) 30 days        
Vesting period (in years)   3 years      
Sales commissions amortization period (in years) 3 years 3 years 1 year    
Maximum          
Accounting Policies [Line Items]          
Typical contract term (in years) 5 years 5 years      
Contract term (in years)   10 years      
Revenue from contract with customer, percentage withheld from progress billing 20.00%        
Accounts receivable, payment term (in days) 60 days        
Vesting period (in years)   6 years      
Sales commissions amortization period (in years) 7 years 7 years 2 years    
Stock Option Plan          
Accounting Policies [Line Items]          
Contractual term (in years)   10 years      
Stock Option Plan | Minimum          
Accounting Policies [Line Items]          
Vesting period (in years)   3 years      
Stock Option Plan | Maximum          
Accounting Policies [Line Items]          
Vesting period (in years)   6 years      
Unbilled Revenues          
Accounting Policies [Line Items]          
Accounts receivable, net   $ 104,200,000 $ 64,600,000    
Retention Receivable | Unbilled Revenues          
Accounting Policies [Line Items]          
Accounts receivable, net   $ 12,200,000 $ 7,200,000    
Subscription And Circulation - Hosting Services | Minimum          
Accounting Policies [Line Items]          
Contract term (in years) 1 year        
Subscription And Circulation - Hosting Services | Maximum          
Accounting Policies [Line Items]          
Contract term (in years) 10 years        
Appraisal services | Minimum          
Accounting Policies [Line Items]          
Contract term (in years) 1 year        
Appraisal services | Maximum          
Accounting Policies [Line Items]          
Contract term (in years) 3 years