Revenue - Performance Obligation (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Performance obligation
Revenue expected to be recognized	$ 145,749
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Performance obligation
Revenue expected to be recognized	$ 55,320
Unsatisfied performance obligation, period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Performance obligation
Revenue expected to be recognized	$ 46,742
Unsatisfied performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Performance obligation
Revenue expected to be recognized	$ 20,302
Unsatisfied performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Performance obligation
Revenue expected to be recognized	$ 10,189
Unsatisfied performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Performance obligation
Revenue expected to be recognized	$ 5,263
Unsatisfied performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Performance obligation
Revenue expected to be recognized	$ 7,933
Unsatisfied performance obligation, period

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130556-203045

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130556-203045

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