Deferred Policy Acquisition Costs (Components Of Underwriting, Acquisition And Insurance Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Policy Acquisition Costs Disclosures [Abstract]
Amortization of policy acquisition costs	$ 1,009,303	$ 894,353	$ 782,221
Other operating expenses	768,208	695,111	714,904
Underwriting, acquisition and insurance expenses	$ 1,777,511	$ 1,589,464	$ 1,497,125