Accounting for Derivative Instruments and Hedging Activities (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash Flow Hedge Loss to be Reclassified within Twelve Months	$ 9,000,000
Derivative, Notional Amount	1,400,000,000	2,200,000,000
Delayed start interest rate derivative instruments	150,000,000
Derivative, Notional Amount that expires in future period	$ 300,000,000