Debt (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Short-term debt and current portion of long-term debt:
Short-term debt, Weighted Average Interest Rate	1.28%	1.70%
Short-term debt	$ 1,604	$ 1,315
Current portion of long-term debt, including capital leases	412,077	258,123
Short-term debt and current portion of long-term debt	557,681	259,438
USCommercialPaperShortTerm [Member]
Short-term debt and current portion of long-term debt:
Commercial Paper	$ 144,000	$ 0