Revenue Recognition - Cumulative Effect of Revenue Recognition Accounting Change (Detail) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	[1]	$ 1,735		$ 789	$ 2,343		$ 1,308
Cost of operations		1,486		650	1,962		1,079
Net income		47		$ 36	82		$ 58
Current assets:
Contracts in progress		918	[2]		918	[2]		$ 621
Stockholders' equity:
Retained earnings		54	[3]		54	[3]		$ (48)
ASU 606 [Member] | Recognition under Previous Guidance [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues					2,550
Cost of operations					2,141
Net income					110
Current assets:
Contracts in progress		926			926
Stockholders' equity:
Retained earnings	[3]	62			62
ASU 606 [Member] | Adjustment [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues					(207)
Cost of operations					(179)
Net income					(28)
Current assets:
Contracts in progress		(8)			(8)
Stockholders' equity:
Retained earnings	[3]	$ (8)			$ (8)

[1] Intercompany transactions were not significant for the three and six months ended June 30, 2018 and 2017, respectively.

[2] Costs incurred in excess of costs recognized (assets) and costs recognized in excess of costs incurred (liabilities) resulted from the exclusion of certain costs when measuring progress toward completion under the cost-to-cost method, prior to our adoption of ASC Topic 606. These remaining amounts will be recognized in Cost of operations as the underlying projects progress.

[3] Includes $20 million of cumulative catch-up adjustment to Retained earnings (Accumulated deficit) on January 1, 2018, upon adoption of ASC 606.