Summary of Debt (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified		12 Months Ended						12 Months Ended		1 Months Ended	12 Months Ended
	Mar. 25, 2008	Dec. 31, 2012 Receivables Credit Facility	Dec. 31, 2011 Receivables Credit Facility	Dec. 31, 2012 Senior Credit Facility	Dec. 31, 2011 Senior Credit Facility	Dec. 31, 2012 5.75% Senior Notes	Dec. 31, 2011 5.75% Senior Notes	Dec. 31, 2012 6.50% Senior Notes	Dec. 31, 2011 6.50% Senior Notes	Jun. 30, 2012 3.90% Senior Notes	Dec. 31, 2012 3.90% Senior Notes	Jun. 26, 2012 3.90% Senior Notes
Debt Instrument [Line Items]
Credit facility, effective interest rate		1.06%	1.15%	1.71%	2.08%
Credit facility, due date		Oct. 11, 2014	Oct. 11, 2014	Oct. 11, 2016	Oct. 11, 2016
Senior notes, discount							$ 514	$ 32	$ 38		$ 338
Senior notes, stated interest percentage	6.50%						5.75%	6.50%	6.50%		3.90%	3.90%
Senior notes, due date						Aug. 01, 2013		Mar. 15, 2018	Mar. 15, 2018	Jun. 15, 2022	Jun. 15, 2022