Debt Facilities - Interest Charges (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Debt Disclosure [Abstract]
Interest expense	$ 76,269	$ 63,756	$ 219,556	$ 199,450
Interest capitalized	1,831	5,565	8,677	13,050
Interest charges incurred	$ 78,100	$ 69,321	$ 228,233	$ 212,500