Revenue Recognition - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Unapproved change orders and claims		$ 472,000,000	$ 117,000,000
Unapproved change orders and claims in our RPO balance		99,000,000	8,000,000
Incentives amount included in transaction prices		89,000,000	$ 0
Incentives amount included in our RPO balance		$ 13,000,000
Cameron Liquefied Natural Gas Project
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Loss on contracts	$ 165,000,000
Cameron Liquefied Natural Gas Project | NCSA [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Percentage of complete acquired on post combination basis		23.00%
Percentage of complete acquired on pre combination basis		88.00%
Reserve for estimated losses		$ 32,000,000
Calpine Power Project
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Loss on contracts	23,000,000
Calpine Power Project | NCSA [Member]
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Percentage of complete acquired on post combination basis		28.00%
Percentage of complete acquired on pre combination basis		89.00%
Reserve for estimated losses		$ 42,000,000
IPL gas power project
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Loss on contracts	$ 33,000,000