Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Net gain (loss) on derivative financial instruments	$ (22,929,000)	$ (25,082,000)
Net deferred losses expected to be reclassified from AOCI over next 12 months	(5,000,000)
Notional value of outstanding derivative contracts	$ 294,000,000
Derivative contracts, maturity date	Feb. 28, 2018
Fair value of derivative contracts	$ 2,000,000
EPCI projects [Member]
Derivative [Line Items]
Notional value of outstanding derivative contracts	$ 148,000,000