Investments (Aggregate Carrying And Approximate Market Values Of Held-To-Maturity Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Securities Held-to-Maturity, Amortized Cost	$ 0	$ 49,036
Securities held-to-maturity, Accumulated Unrecognized Holding Gain	0	1,562
Securities held-to-maturity, Accumulated Unrecognized Holding Loss	0	0
Securities held-to-maturity, Estimated Fair Value	0	50,598
Mortgage-backed securities: U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Securities Held-to-Maturity, Amortized Cost	0	49,036
Securities held-to-maturity, Accumulated Unrecognized Holding Gain	0	1,562
Securities held-to-maturity, Accumulated Unrecognized Holding Loss	0	0
Securities held-to-maturity, Estimated Fair Value	$ 0	$ 50,598