Derivative Financial Instruments (Hedged Items In Fair Value Hedges) (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Carrying value of the hedged items, available for sale debt securities	$ 2,826,200,000	$ 2,981,000,000.0
Cumulative hedge accounting basis adjustment, available for sale debt securities	63,300,000	3,300,000
Carrying value of the hedged items, senior notes and long-term subordinated debt	2,745,000,000.0	1,748,500,000
Cumulative hedge accounting basis adjustment, senior notes and long-term subordinated debt	261,800,000	126,900,000
CARRYING VALUE OF THE HEDGED ITEMS	5,571,200,000	4,729,500,000
Cumulative Hedge Accounting Basis Adjustment	325,100,000	130,200,000
Hedged asset fair value hedge discontinued cumulative increase decrease	6,700,000	1,500,000
Hedged liability fair value hedge discontinued cumulative increase decrease	$ 0	$ 0