Derivative Financial Instruments - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net gain (loss) on derivative financial instruments	$ (30,090,000)	$ (45,386,000)
Net deferred losses expected to be reclassified from AOCI over next 12 months	30,200,000
Notional value of outstanding derivative contracts	1,000,000
Derivative contracts, maturity date	Dec. 31, 2017
Fair value of derivative contracts	2,600,000
EPCI projects [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional value of outstanding derivative contracts	$ 735,000,000