Significant Components of Prepaid Expenses and Other Current Assets (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Prepaid expenses	$ 40,947	$ 24,615
Supplies inventory	7,467	8,881
Other	34,822	36,428
Total	$ 83,236	$ 69,924