Description of Business and Summary of Significant Accounting Policies (Revenue Contracted Not Recognized) (Details)
$ in Millions |
3 Months Ended |
|
Mar. 31, 2018
USD ($)
|
|---|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
|
| Contracted not recognized revenue |
$ 8.8
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01 |
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
|
| Percentage of contracted not recognized revenue expected to be recognized |
41.00%
|
| Contracted not recognized revenue, recognition period |
12 months
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01 | Minimum |
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
|
| Contracted not recognized revenue, recognition period |
3 years
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01 | Maximum |
|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
|
| Contracted not recognized revenue, recognition period |
4 years
|