Capitalized Interest - Summary of Interest Costs Incurred, Capitalized, Expensed and Charged to Cost of Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Interest Costs Incurred [Abstract]
Interest capitalized, beginning of period	$ 4,271	$ 3,618	$ 4,072	$ 3,294
Interest incurred	6,262	6,200	12,525	12,423
Interest charged to interest expense	(5,956)	(5,723)	(11,874)	(11,517)
Interest charged to cost of sales	(245)	(285)	(391)	(390)
Interest capitalized, end of period	$ 4,332	$ 3,810	$ 4,332	$ 3,810