Debt (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Dec. 31, 2011
Short-term debt and current portion of long-term debt:
Current portion of long-term debt, including capital leases	$ 374,355	$ 269,275
Total short-term debt and current portion of long-term debt	443,629	274,366
USCommercialPaperShortTerm [Member]
Short-term debt and current portion of long-term debt:
Commercial Paper	65,000	0
Short-term debt [Member]
Short-term debt and current portion of long-term debt:
Short-term debt, Weighted Average Interest Rate	1.42%	1.45%
Maturity date range, start	2012
Short-term debt	$ 4,274	$ 5,091

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

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When presenting a range of maturity dates, the earliest date when the outstanding debt instruments are required to be repaid. May be presented in a variety of ways (for example: year only, month and year, day, month and year, and number of years).

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