Accounts Receivable - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Feb. 04, 2013	Dec. 31, 2012
Receivables [Abstract]
Trade accounts receivable securitization facility	$ 500,000,000
Maximum undivided ownership interest pooled accounts receivable amount sold	500,000,000
Deferred financing fees		600,000
Securitization facility	$ 385,000,000		$ 298,000,000