Revenue (Details 2) $ in Thousands	Mar. 31, 2019 USD ($)
Period 1 [Member]
Revenue, Remaining Performance Obligation, Amount	$ 235,920
Period 2 [Member]
Revenue, Remaining Performance Obligation, Amount	261,390
Period 3 [Member]
Revenue, Remaining Performance Obligation, Amount	222,523
Period 4 [Member]
Revenue, Remaining Performance Obligation, Amount	210,652
Period 5 [Member]
Revenue, Remaining Performance Obligation, Amount	192,783
Thereafter [Member]
Revenue, Remaining Performance Obligation, Amount	$ 1,409,836