Debt (Details Textuals) (USD $)	6 Months Ended								6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Letter of Credit [Member]	Jun. 30, 2012 Global Revolving Credit Facility [Member]	Jun. 30, 2012 U.S Commercial Paper, Long-Term [Member]	Dec. 31, 2011 U.S Commercial Paper, Long-Term [Member]	Jun. 30, 2012 Canadian Commerial Paper [Member]	Dec. 31, 2011 Canadian Commerial Paper [Member]	Jun. 30, 2012 Medium-term Notes [Member]	Feb. 28, 2012 350 million unsecured medium-term notes due March 2015 [Member]
Debt Instrument [Line Items]
Unamortized original issue discounts	$ 9,000,000	$ 8,700,000
Notional amount of the executed interest rate swap designated as a fair value hedge	550,000,000	550,000,000
Line of Credit Facility [Abstract]
Maximum borrowing capacity under global revolving credit facility			75,000,000	900,000,000
Number of lending institutions	12
Letter of credit outstanding amount			0
Global revolving credit facility covenant terms, debt to consolidated tangible net worth ratio	less than or equal to 300%
Debt to consolidated tangible net worth ratio	200.00%
Debt (Textuals) [Abstract]
Commercial paper classified as long term debt	604,343,000	415,936,000			571,897,000	415,936,000	32,446,000	0
Face amount of unsecured medium-term notes issued										350,000,000
Repurchase price condition of notes									101% of principal plus accrued and unpaid interest
Total available proceeds under trade receivables purchase and sale program	175,000,000
Number of days under trade trade receivables purchase and sale program	364 days
Trade Receivables Purchase And Sale Program Amounts Outstanding	0	0
Letters of Credit and Surety Bonds Outstanding	$ 270,500,000	$ 271,000,000