Revenues - Remaining Performance Obligations & Revenue Expected to be recognized (Details)	Jun. 30, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-06-30
Remaining Performance Obligation, Expected Timing of Satisfaction
Percentage of remaining performance obligation expected to be recognized in period	67.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-05
Remaining Performance Obligation, Expected Timing of Satisfaction
Percentage of remaining performance obligation expected to be recognized in period	19.00%

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Period Type:	duration