Significant Components of Prepaid Expenses and Other Current Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Prepaid expenses	$ 35,696	$ 24,615
Supplies inventory	11,650	8,881
Other	40,176	36,710
Total	$ 87,522	$ 70,206