Property and Equipment, Net - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Property Plant And Equipment [Abstract]
Depreciation expense	$ 65.1	$ 54.5	$ 198.1	$ 152.8
Non-cash capital expenditures			$ 12.0		$ 17.3