Loss And Loss Adjustment Expense Reserves (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended	7 Months Ended	9 Months Ended
	Jan. 31, 2018	Jun. 30, 2019	Dec. 31, 2018	Jul. 31, 2018	Sep. 30, 2020	Sep. 30, 2019
Unusual or Infrequent Item, or Both [Line Items]
Prior year claims and claims adjustment expense					$ 25,511	$ 10,323
Adjustments for prior year claims					786,180	715,451
Loss from catastrophes					43,000	17,000
Credit Agreement [Member] | LIBOR [Member] | FFL [Member]
Unusual or Infrequent Item, or Both [Line Items]
Basis spread on variable rate	1.28%		1.05%	1.20%
Catastrophe [Member]
Unusual or Infrequent Item, or Both [Line Items]
Adjustments for prior year claims					5,000	3,000
Liability for catastrophe claims, carrying amount					$ 48,000
Loss from catastrophes						$ 20,000
Fire [Member]
Unusual or Infrequent Item, or Both [Line Items]
Loss from catastrophes, net of reinsurance benefits		$ 40,000
Liability for catastrophe claims, carrying amount		208,000
Benefit from sale of subrogation rights		$ 10,000