Reserve For Losses, LAE And Future Policy Benefit Reserve (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]
Incurred related to: Current year	$ 4,572,640	$ 3,559,505
Covid-19 [Member]
Reserve For Losses LAE And Future Policy Benefit Reserve [Line Items]
Incurred related to: Current year	$ 434,918

Amount, after effects of reinsurance, of expense for claims incurred in the current reporting period and related claims settlement costs.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Name:	us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration