Debt Facilities - Interest Charges (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Debt Disclosure [Abstract]
Interest expense	$ 121,828	$ 92,200	$ 352,554	$ 293,395
Interest capitalized	6,174	3,234	20,573	9,479
Interest charges incurred	128,002	95,434	373,127	302,874
Interest paid, net of capitalized interest	$ 122,800	$ 107,900	$ 321,800	$ 262,100