Revenues by Geography, Concentration of Credit Risk and Remaining Performance Obligations - Additional Information 1 (Detail) $ in Billions |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2018
USD ($)
Customer
|
Sep. 30, 2017
Customer
|
Sep. 30, 2018
USD ($)
Customer
|
Sep. 30, 2017
Customer
|
|
Revenue From Contract With Customer [Abstract] | ||||
Number of clients served | Customer | 0 | 0 | 0 | 0 |
Revenue expected to be recognized in future from remaining performance obligations | $ | $ 18.3 | $ 18.3 |