Derivative and Hedging Activity (Schedule of Derivatives) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
	May 31, 2012 contract	Mar. 31, 2012 contract	Dec. 31, 2011 contract	Nov. 30, 2011 contract	Mar. 31, 2010 contract	Dec. 31, 2009 contract
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative, Inception Date	May 01, 2012	Mar. 01, 2012	Dec. 01, 2011	Nov. 01, 2011	Mar. 01, 2010	Dec. 01, 2009
Derivative, Maturity Date	May 27, 2016	Jun. 30, 2015	Dec. 31, 2015	May 31, 2015	May 31, 2012	May 31, 2012
Derivative, Fixed Interest Rate	1.15%	1.01%	1.17%	0.98%	1.45%	1.83%
Derivative, Notional Amount	$ 5.0	$ 5.0	$ 10.0	$ 10.0	$ 30.0	$ 60.0
Derivative, Number of Instruments Held	1	1	2	1	2	4