Losses And Loss Adjustment Expense Reserves (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Unusual or Infrequent Item, or Both [Line Items]
Prior years claims and claim adjustment expense	$ 18,347	$ 69,134
Catastrophe [Member]
Unusual or Infrequent Item, or Both [Line Items]
Pre-tax catastrophe losses	$ 59,000	$ 23,000