Derivative Financial Instruments (Schedule of Interest Rate Swap Derivatives) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Notional Value		$ 500
Swap Derivative 1 Point 02 Percent Maturing January 2, 2016 [Member]
Derivative [Line Items]
Notional Value	$ 500	$ 500	$ 500
Effective Date		Jan. 02, 2014	Jan. 02, 2014
Expiration Date	Jan. 02, 2016		Jan. 02, 2016
Fixed Rate	1.02%	0.94%	1.02%