Quarterly report pursuant to Section 13 or 15(d)

Revenue - Performance Obligations (Details)

v3.19.3
Revenue - Performance Obligations (Details)
Sep. 30, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 | Discovery Services  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, expected timing of satisfaction, period 1 year