Financing Arrangements - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity	$ 1,500,000,000
Credit facility, term	5 years
Credit facility Interest rate above LIBOR	1.50%
Current maturities of long-term debt	349,975,000	41,000
Long-term debt	974,541,000	939,350,000
Before Amendment
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity	1,900,000,000
Credit facility, maturity date	2012-07
Revolving Facility
Line of Credit Facility [Line Items]
Long-term debt	$ 725,000,000