Long Term Debt (Parenthetical) (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2012 6.6% Senior Notes, Due 2018	Sep. 30, 2012 6.6% Senior Notes, Due 2018	Sep. 30, 2012 7% Debentures, Due 2025	Sep. 30, 2012 6.25% Senior Notes, Due 2037	Sep. 30, 2012 Term Loan Facility, Due 2015	Dec. 31, 2011 Term Loan Facility, Due 2015	Sep. 30, 2011 Term Loan Facility, Due 2015	Sep. 30, 2012 Revolving Facility	Dec. 31, 2011 Revolving Facility	Sep. 30, 2011 Revolving Facility	Sep. 30, 2012 AR Credit Facility	Dec. 31, 2011 AR Credit Facility	Sep. 30, 2011 AR Credit Facility
Debt Instrument
Maturity date	2018	2018	2025	2037	2015
Interest rate on notes	6.60%	6.60%	7.00%	6.25%
Interest rate on term loan					2.22%	2.20%	1.99%
Credit Facility interest rate								1.92%	2.64%	1.61%	1.00%	1.66%	1.60%