Derivative Financial Instruments (Hedged Items In Fair Value Hedges) (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Carrying value of the hedged items, available for sale debt securities	$ 1,571,100,000	$ 1,677,400,000
Cumulative hedge accounting basis adjustment, available for sale debt securities	22,800,000	11,100,000
Carrying value of the hedged items, senior notes and long-term subordinated debt	2,745,800,000	2,745,600,000
Cumulative hedge accounting basis adjustment, senior notes and long-term subordinated debt	107,600,000	59,500,000
Carrying Value of the Hedged Items	4,316,900,000	4,423,000,000
Cumulative Hedge Accounting Basis Adjustment	130,400,000	70,600,000
Hedged asset fair value hedge discontinued cumulative increase decrease	9,400,000	9,600,000
Hedged liability fair value hedge discontinued cumulative increase decrease	$ 0	$ 0