XML 64 R43.htm IDEA: XBRL DOCUMENT v3.19.1
NATURE OF BUSINESS AND ACCOUNTING POLICIES - Costs Incurred to Develop Software for Internal Use (Details) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Property, Plant and Equipment [Line Items]      
Impairment of internal use software $ 0 $ 0 $ 0
Software costs capitalized during the period 6,700,000 3,100,000 3,100,000
Capitalized computer software, net 10,800,000 6,700,000  
Capitalized computer software, amortization $ 2,600,000 $ 1,600,000 $ 1,000,000.0
Computer software | Minimum      
Property, Plant and Equipment [Line Items]      
Useful Life 3 years    
Computer software | Maximum      
Property, Plant and Equipment [Line Items]      
Useful Life 5 years