Short-Term Borrowings and Credit Arrangements (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Short-term Debt [Line Items]
Commercial Paper, Balance	$ 140,950,000	$ 122,934,000
Maximum borrowing capacity under commercial paper program	250,000,000
Short term borrowings maximum days outstanding	270 days
Short-term Debt [Member]
Short-term Debt [Line Items]
Commercial Paper, Balance	141,000,000	122,900,000
Commercial Paper, Interest Rate	0.41%	0.53%
Maximum short-term debt outstanding	199,900,000	166,900,000
Average short-term debt outstanding	$ 69,000,000	$ 78,900,000
Weighted average interest rate	0.40%	0.48%