Quarterly report pursuant to Section 13 or 15(d)

Revenue (Obligation) (Details)

v3.19.1
Revenue (Obligation) (Details)
$ in Thousands
 3 Months Ended
Mar. 31, 2019
USD ($)
Revenue from Contract with Customer [Abstract]  
Total $ 498,881
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01  
Revenue from Contract with Customer [Abstract]  
Total $ 159,916
Remaining Performance Obligations  
Revenue recognition period 9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01  
Revenue from Contract with Customer [Abstract]  
Total $ 138,921
Remaining Performance Obligations  
Revenue recognition period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01  
Revenue from Contract with Customer [Abstract]  
Total $ 83,286
Remaining Performance Obligations  
Revenue recognition period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01  
Revenue from Contract with Customer [Abstract]  
Total $ 55,311
Remaining Performance Obligations  
Revenue recognition period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01  
Revenue from Contract with Customer [Abstract]  
Total $ 36,640
Remaining Performance Obligations  
Revenue recognition period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)  
Remaining Performance Obligations  
Revenue recognition period