Derivative Financial Instruments (Contractual and Weighted-Average Interest Rates, Which Include the Effects of Hedges Related to Financial Instruments) (Details) (Long-Term Debt [Member])	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Long-Term Debt [Member]
Contractual Rates	3.55%	3.73%	3.55%	3.74%
Rate Including Impact of Hedges	3.16%	3.23%	3.18%	3.26%