Loss And Loss Adjustment Expense Reserves (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Unusual or Infrequent Item, or Both [Line Items]
Prior year claims and claims adjustment expense	$ 1,362	$ 42,652
Adjustments for prior year claims	344,718	345,826
Catastrophe [Member]
Unusual or Infrequent Item, or Both [Line Items]
Loss from catastrophes	11,000
Loss from catastrophes, net of reinsurance benefits	5,000	$ 9,000
Adjustments for prior year claims	6,000
Fire [Member]
Unusual or Infrequent Item, or Both [Line Items]
Loss from catastrophes	208,000
Loss from catastrophes, net of reinsurance benefits	40,000
Benefit from sale of subrogation rights	$ 10,000