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		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI			$ 10.7	$ (16.8)
Interest Expense [Member]
Derivative Instruments Gain Loss [Line Items]
Gain Reclassified from AOCI into Net Earnings	$ 2.2	$ 1.5	$ 4.1	$ 1.8