Variable Interest Entities (Schedule Of Variable Interest Entities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Other investments, at fair value	$ 4,833	$ 2,522	$ 2,779	$ 2,756
Maximum exposure	4,503	5,413
Alternative Investments [Member]
Variable Interest Entity [Line Items]
Other investments, at fair value	$ 4,503	$ 5,413