Segment Data - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of business segments	2
Total assets held in Brazil	$ 6,584,428	$ 6,595,617	$ 6,595,617
Outside of United States [Member]
Segment Reporting Information [Line Items]
Percentage of revenue generated from the foreign countries	7.00%	5.90%
Percentage of total assets in the foreign countries	11.30%		12.20%
Total assets held in Brazil			$ 178,100