Derivative Financial Instruments (Summary of Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income) (Details) - Derivatives in Cash Flow Hedging Relationships [Member] - Interest Rate Swap Contracts [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI	$ 7.0	$ (15.6)
Interest Expense [Member]
Derivative Instruments Gain Loss [Line Items]
Gain (Loss) Reclassified from AOCI into Net Earnings (Loss)	$ 1.9	$ 0.3