Capitalized Interest Costs and Total Interest Costs Incurred (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Capitalized Interest [Line Items]
Capitalized interest cost	$ 2,716	$ 2,675	$ 3,637
Total interest cost incurred before recognition of the capitalized amount	$ 215,783	$ 223,303	$ 185,240