Revenue Recognition - Summary of RPOs by Segment (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 15,376	$ 10,913
Remaining performance obligations, Percentage	100.00%	100.00%
NCSA [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 8,581	$ 5,649
Remaining performance obligations, Percentage	56.00%	52.00%
EARC [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 1,914	$ 1,378
Remaining performance obligations, Percentage	12.00%	12.00%
MENA [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 2,879	$ 1,834
Remaining performance obligations, Percentage	19.00%	17.00%
APAC [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 1,401	$ 1,420
Remaining performance obligations, Percentage	9.00%	13.00%
Technology [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 601	$ 632
Remaining performance obligations, Percentage	4.00%	6.00%