Supplemental Balance Sheet Information - Remaining Performance Obligations (Details) $ in Millions |
Jun. 30, 2018
USD ($)
|
|---|---|
| Balance Sheet Related Disclosures [Abstract] | |
| Revenue allocated to remaining performance obligations that are unsatisfied or partially unsatisfied | $ 186 |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01 | |
| Balance Sheet Related Disclosures [Abstract] | |
| Revenue allocated to remaining performance obligations that are unsatisfied or partially unsatisfied | $ 164 |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |
| Performance obligations expected to be satisfied, expected timing | 1 year |