Revenue Recognition (Performance obligation) (Details)
$ in Millions |
Dec. 31, 2018
USD ($)
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
|
| Contracted not recognized revenue |
$ 9.8
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 |
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
|
| Expected timing of satisfaction |
12 months
|
| Percentage expected to be recognized |
44.00%
|
| Minimum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 |
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
|
| Expected timing of satisfaction |
3 years
|
| Maximum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 |
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
|
| Expected timing of satisfaction |
4 years
|