Credit Facilities, Short-term Borrowings and Long-term Debt (Details) (USD $) In Thousands, unless otherwise specified					6 Months Ended	12 Months Ended	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010		Jun. 30, 2011 Bank Borrowings [Member]	Dec. 31, 2010 Bank Borrowings [Member]	Jun. 30, 2010 Commercial Paper [Member]
Short-term Borrowings
Bank borrowings	$ 100,000	$ 285,500	$ 0
Commercial paper	0	0	320,000
Total	$ 100,000	$ 285,500	$ 320,000	[1]
Maturity					15 days	3 - 74 days	1 - 2 days
Weighted-average interest rate					0.53%	0.59%	0.70%

[1] As Restated, See Note 1