Segment Information - Additional Information (Detail) (USD $) In Billions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Information [Line Items]
Maximum percentage of consolidated revenue customers	10.00%	10.00%	10.00%
Revenue in the United States	$ 12.0	$ 11.8	$ 10.7