Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, plant and equipment, net	$ 3,230,523		$ 3,230,523		$ 3,004,067
Depreciation expense on property, plant and equipment	$ 57,930	$ 51,263	$ 113,971	$ 100,921