Annual report pursuant to Section 13 and 15(d)

Revenue from Contracts with Customers - Summary of Future Obligations (Details)

v3.19.1
Revenue from Contracts with Customers - Summary of Future Obligations (Details)
$ in Thousands
Dec. 31, 2018
USD ($)
Revenue from Contract with Customer [Abstract]  
Deferred revenue $ 6,522
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01  
Revenue from Contract with Customer [Abstract]  
Deferred revenue $ 4,071
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01  
Revenue from Contract with Customer [Abstract]  
Deferred revenue $ 898
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01  
Revenue from Contract with Customer [Abstract]  
Deferred revenue $ 872
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01  
Revenue from Contract with Customer [Abstract]  
Deferred revenue $ 681
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, expected timing of satisfaction, period 2 years