Summary of Debt (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Receivables Credit Facility
Debt Instrument [Line Items]
Credit facility, effective interest rate	1.10%	1.15%
Credit facility, due date	Oct. 11, 2014	Oct. 11, 2014
Senior Credit Facility
Debt Instrument [Line Items]
Credit facility, effective interest rate	1.75%	2.08%
Credit facility, due date	Oct. 11, 2016	Oct. 11, 2016
5.75% Senior Notes
Debt Instrument [Line Items]
Senior notes, discount	343	514
Senior notes, stated interest percentage	5.75%	5.75%
Senior notes, due date	Aug. 01, 2013	Aug. 01, 2013
6.50% Senior Notes
Debt Instrument [Line Items]
Senior notes, discount	35	38
Senior notes, stated interest percentage	6.50%	6.50%
Senior notes, due date	Mar. 15, 2018	Mar. 15, 2018
Senior Notes Three Point Nine Percentage Senior Notes
Debt Instrument [Line Items]
Senior notes, discount	355
Senior notes, stated interest percentage	3.90%
Senior notes, due date	Jun. 15, 2022