Derivative Instruments (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Derivative Instruments [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 15
Collateral Requirement If Netting Agreements Not In Place	9
Exposure Associated With Collateralization Events	$ 15