Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Deferred policy acquisition cost amortization period	1 year
Tax benefit greater than 50%	50.00%
Insurance premiums revenue recognition period	1 year
Stock-based compensation expense, net of taxes	$ 13.0	$ 11.9	$ 14.3