Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 8.0
Credit Derivative, Maximum Exposure, Undiscounted	0.0	$ 1.0
Credit Risk Derivatives, at Fair Value, Net Asset (Liability) (less than)	$ 0.0	$ 0.0